TWISTING, TURNING, TILTING AND OTHER GROOVY …rapidproto/outreach/mech.pdfTwisting Turning Tilting and Other Groovy Movements – 1 TWISTING, TURNING, TILTING AND OTHER GROOVY MOVEMENTS

Twisting Turning Tilting and Other Groovy Movements – 1

TWISTING, TURNING, TILTING AND OTHERGROOVY MOVEMENTS

A level 4 Systems Strand unit of work focusing on:

� machines and mechanisms; and

� the field of Mechanical Engineering

Contents

Section 1: The Unit of Work ............................................................ 2

1a: Background information (or all you need to know about mechanicalthings to appear knowledgeable) ................................................ 2

1b: The design brief ......................................................................11

1c: What happens in the four phases? ............................................ 12

1d: Technical knowledge and skill content ....................................... 13

Section 2: The Engineers .............................................................. 31

2a: Paul ...................................................................................... 31

2b: Barbara ................................................................................. 32

Section 3: Technical Resources ...................................................... 33

3a: Suggestions on how to solve the problem.................................. 33

3b: Some simple and easy tests..................................................... 34

Section 4: Assessment ................................................................. 37

Section 5: Further Options ............................................................ 42

5a: Integrating learning areas......................................................... 42

5b: Alternative design briefs .......................................................... 42

5c: Working with students of differing abilities ................................ 44

Section 6: Some Useful Information ............................................... 47

6a: Question sheet � Paul ............................................................. 48

6b: Question sheet � Barbara ........................................................ 49

6c: Letter for the students� parents ................................................ 50

6d: Possible solutions to the design brief in Section 1 ...................... 51

6e: Some possible mathematics associated with this unit. ................ 52

6f: Introducing the unit ................................................................. 53


Section 1: THE UNIT OF WORK

Warning – Health Hazard(Read this before you continue.)

This section seems to have a lot of pages but don’t let that put you off.The background information is there to get you quickly up to ‘expert’level, or in other words one page ahead of the students. The informa-tion provided is certainly more than you would use in one unit ofwork. The advice, which you could ignore with disastrous results, isto select what you think you need. Choose carefully what you wantthe students to learn and focus on that. Don’t try to do everything.There will be other opportunities. When in doubt read the instruc-tions, in this case the introduction.

1A: BACKGROUND INFORMATION (OR ALL YOU NEED TO KNOW

ABOUT MECHANICAL THINGS TO APPEAR KNOWLEDGEABLE)

If you are still in the early stages of developing your technology course this unit may be your intro-duction to that strand of technology called systems. The systems strand covers two areas of technol-ogy: the first consists of those devices that use electricity and all the bits and pieces that make upelectrical circuits; the second is that groups of things we commonly call machines. This unit is aboutmachines and it will focus on a very special type of simple machine known as the lever. The informa-tion below begins with machines because armed with a little knowledge about these fascinatingthings you should find the systems stuff a little easier. There will be heaps of good information aboutlevers later in this section.

CAUTION

THIS COULD

EASILY BECOME

A HEALTH HAZARD

OUTPUT

INPUT THE PROCESS


MACHINES

Machines are everywhereWe spend our lives surrounded by machines. They come in all shapes and sizes and some are sofamiliar we never really think about them unless they stop working. To illustrate this let us look atthat very important part of every day – the time spent in the bathroom.

• After you entered the shower recess you shut the sliding glass door.• While under the shower you used the tap to control the flow of water.• After getting out of the shower you used a hair dyer to dry your hair.• To clean your teeth you unscrewed the top of the tube of toothpaste.• To trim your toenails you used a pair of scissors.• To get in and out of the bathroom you turned the knob on the door lock.

Each one of these actions involved the use of a machine. If you find this difficult to believe read onand you will discover the secrets of your ‘mechanical’ bathroom.

The mechanical bathroom• The glass door has little wheels at the top that roll along a track.• The handle on the tap is really a lever.• Inside the hair dryer is a small electric fan that has moving parts.• A screw holds on the top of the toothpaste.• Scissors are another example of levers at work.• If the door handle is round then it is a wheel and axle. The alternative type of handle is a lever

that you push down.Devices that have moving parts such as levers and wheels are examples of machines at work. Theymay be very simple machines but they are still machines.

Why are some things called machines and others not?

Let us look at some features that help us understand something about these things we call machines.

People use machines to extend their capability to do things.We use machines to make work easier because they do our work faster or better. For example;

• A lawn mower cuts grass quicker and better than we could using a pair of scissors, and scis-sors are better than nothing at all. The lawn mower and scissors are both machines.

• At your next weekly visit to the su-permarket you have two options: touse a trolley or to carry everythingin a basket. Most people use a ma-chine known as a trolley because itmakes the task easier.

• A couple of generations ago womenwould set aside Monday as wash-ing day and it was all done by hand.Today we use washing machinesand very few people would will-ingly choose the old-fashionedmethod.

• Inside your video recorder there issomething that winds the tape fromone reel to the other at the correct speed. You could do this by hand but getting the speed rightand constant would be a bit difficult. The bit that does the winding in the VCR is a machine.

• You get a much better idea of how we use machines to do our work if you consider examplessuch as Boeing 747s, the large diggers that excavate coal from the open cut mines aroundMorwell, the roof that closes at Melbourne Park (the tennis centre), or the almost endlessmachines that are used in the production of cars at the Ford factory.


Machines may be simple or complex, small or large, visible or hidden, but they all do the same basicthing which is to help us work faster or better.

Machines are made up of a numberof parts joined together in a par-ticular way.Armed with spanners, screwdrivers and anassortment of suitable tools you set aboutdisassembling your washing machine, carengine or electric knife and you would ex-pect to end up with a number of parts ofdifferent shapes and sizes. If you were askedto put all the parts back together the resultwould not be so predictable. The number

of parts may vary from a few to a few thousand but we all seem to know that if they are not assembledcorrectly then whatever it is will not work properly. The line between a machine and a pile of junk isvery fine indeed.

Machines have some parts that moveEven though we can’t see inside a machine such as acar engine we somehow know that there are partsmoving up and down, sliding in and out or whizzingaround at different speeds. The way they move, thedirection in which they move and the speed at whichthey move are all very important features of a ma-chine.

Machines convert energyEnergy is the stuff that makes things happen, and inthe case of machines it makes things move. Fromyour current knowledge of machines you know thatthere are three ways of getting a machine to do what-ever it is supposed to do.

• You can supply the energy by turning a handle, pushing on pedal, or just pushing and pulling.• Connect it to a power supply (power point or battery) and turn on the switch.• Fill the tank up with petrol or LPG and start it up.

Electricity or petrol by themselves do not make work any easier. We have to convert them intomechanical energy that comes from the moving parts in a machine. It is this mechanical energy thathelps us to cut materials, lift objects, transport people and goods and the host of other things we usemachines to achieve.

Machines are a very diverse category of thingsMachines are now part of our lives. They come in many shapes and sizes and perform many func-tions. Some simple classifications are shown below.

• Big and small (Boeing 747 and watch)• Simple and complex (hand-operated can-opener and robots)• Old and new (hand lawn mowers and motor mowers)• Cheap and expensive (bicycles and Formula 1 racing cars)• Common and not-so-common (sewing machines and excavators in open-cut mining opera-

tions)• Environmentally friendly and not-s- environmentally friendly (bicycles and motor cars)

Whatever the category they all share the features described above.


Even the complex is really simpleThe problem with many machines is that all the working parts are hidden behind some form of cover.For example, the motor and other important parts are covered by the body of your car and the thingsthat make the agitator agitate the tub spin, and the pump work in the washing machine are all insidea large white box. The machines that operate the lifts, escalators and air-conditioning in large build-ings are usually hidden in basements or on roofs.Things that are not visible always have an air of mystery about them. Anything that is large or hasmany parts is thought to be really complicated and beyond the understanding of the non-expert. Thismyth is easily shattered. All those complex examples of machines are really made up of differentcombinations of very simple machines.Leonard Maunder writing about machines states, If we include the invention of tools, the history ofmachines is almost as long as the history of humanity. What we now call simple machines havebeen around for centuries yet they still form the basic units for large and complex machines of today.Always beware of people who say something is simple because it tends to be anything but. However,in the case of machines there may be something in it and a look at what are described as simplemachines may provide valuable clues to understanding this machine mystery. The examples belowdescribe some uses of typical simple machines.

• Inclined plane: Smart people know that it is easier to get to the first floor by walking up aramp rather than climbing up a rope. Of course coming down is a different matter. If you can’tget a ramp a staircase will serve the same purpose because it is really a ramp disguised as a setof stairs. Even a spiral staircase is still an inclined plane.

• Pulleys: Anyone who has ever watched a pirate film will know that the sail-ors always raised the sails by pulling on ropes that ran over a number of pulleysto make the task easier. You might ask what is easy about raising a sail in themiddle of storm. Well, everything is relative and standing on the deck and pull-ing on a rope was much easier than standing at the top of the mast and trying topull the sail up.

• Levers: Everyone knows that a screw-driver is the ideal tool to get the lid off a can

of paint. Your dentist uses a pair of pliers to pull thoseaching teeth out, especially the ones that stop hurting assoon as you enter the waiting room. Successful casino pa-trons who know about levers would use a wheelbarrow totake their winnings to the bank.

• The screw: If you have ever had the pleasure of changinga flat tyre you would have used a jack to lift the car. Cleverpeople usually get someone else to do the hard work for them. In either case the jack used ascrew that allowed you (or someone else) to use one hand to raise the car. If you don’t believethis go straight out and jack up your car. If you don’t know what a screw looks like you mayhave to attend a remedial program for the mechanically disadvantaged.


• Wheel and axle: Try and imagine a world without wheels. Youwould have to carry or drag all those things around the supermarket;roller blading without rollers would not be half as enjoyable; andyour car would become a permanent fixture in your driveway. It’salso hard to imagine roulette or Tattslotto without a wheel. Kids wouldnever experience the joys of tricycle riding.

• Gears: Gears are those funny wheelswith things like teeth around the outside.

Gears come in all sizes and they are used to change speed and pro-vide more power. Car drivers with manual gears know all about chang-ing gears at different speeds. Next time you’re cycling in that leg ofthe triathlon remember that the gears on your bike are there to helpyou go faster and with less effort.

Don’t let all these wonderful names put you off because they really are simple machines in the truestsense. Before moving on to the authentic and exciting machine information it would be useful to takea look at the concept of systems that form one strand in the CSF. If you are wondering about theconnection between machines and systems, then wonder no more. Machines are one category of thesystems covered in this strand.


SYSTEMS

The mystery of the systemSystems must be important because they form one of the three strands in the Technology componentof the CSF. The word system is one that we use frequently and in different contexts so it is worthwhilespending a little time deciding what we mean by systems in technology. Here are four examples ofhow system is used

1. The first involves a group of people working in an organised way for a particular purpose. Someexamples are:• educational systems• political systems• legal systems• religious systems

2. The second example describes groups of objects connected in a specific way to produce a desiredoutcome, such as:• communication systems• transport systems• sound systems• computer systems• manufacturing systems

3. The third example is where we use system to describe a procedure or process, such as:• betting system• system of recording student results• budgeting system• numbering system

4. The fourth example is where it is used in a colloquial sense, such as:• buck the system• get it out of your system

In each example the word system is used as a noun. It is the name of something and, with the excep-tion of the colloquial usage, there has to be some additional information before it makes any sense. Inother words, if you say Australia has a good system it is meaningless. However, if you say Australiahas a good telephone system then everyone understands what you are saying and they can then agreeor disagree.

A dictionary definitionSystem, therefore, is the name of something, but the name of nothing in particular. This apparentcontradiction may be explained by looking at some definitions. A dictionary is always the logicalfirst resort when searching for meaning, but in this instance it may not appear to be particularlyhelpful as The Macquarie Dictionary provides fourteen different definitions for system. The first andgeneral definition is:

An assemblage or combination of things or parts forming a complex or unitary whole.

If we can translate this definition into simple language we get:

a number of parts combined, interconnected, having an individual character, complete in itself

To double check you could refer to another very reputable source, Chambers Scientific and Technol-ogy Dictionary, and there you will find five separate entries; there are specific chemistry, biology,electrical engineering and geological definitions. In addition there is a general definition:

Generally anything formed of parts placed together or adjusted into a regular or connected whole.

The two definitions seem to be compatible, they both mention parts connected together and forminga whole.


The CSF definitionPerhaps it is time to look at what is said about systems in the CSF. It does not provide a nice concisetwo-line definition, but if you read the section on page 13 carefully you discover that:

• systems are combinations of human and technical elements that work together to achievespecified outcomes

• each system contains separate parts or elements connected in a specific way to make thesystem work

• technological systems have particular inputs, processes and outputs controlled by people.Once again you find that a system has a number of parts connected in a particular way. However,some new ideas are expressed.

• People are somehow involved.• A technological system can be described by its input, process and output.

Systems and peopleSystems and people are related in two ways.

• It is people who identify the need, decide there is a way to solve the problem and then designand build the system.

• It is people who control the system. Sometimes they just set the controls and start it up, such asan airconditioner or some other automated machine. In other instances they are actually partof the ongoing operation of the system. On your bicycle you must provide the energy to make

it go, steer it, and also make decisions to pedal faster orslower. When you drive your car you do similar things andbecome part of that system.

The air-conditioner is an example of the set and forget rela-tionship.

The bicycle is an example of a relationship wherethe rider is part of the actual operation

The input-process-output thingBy now you would have read the Systems strand in the CSF and one of the many apparently strangeconcepts is the idea of input-process-output. The secret of the input-process-output can now be re-vealed. All systems, including machines, can be described by their input-process-output, and thismay be shown in what is know as the universal systems diagram, such as the one below.

INPUT ð PROCESS ð OUTPUT

Before you throw your hands up in horror and think about changing jobs, think back to what you havelearnt about machines.

1. A machine must be used to change something into something else otherwise why have it.2. We can think of the ‘something’ as the input and the ‘something else’ as the ouput.3. The change that takes place is the process.

One of the really important inputs and outputs is energy. More about energy in the Content part of thissection. If you still have some energy left, read on.

• Lift that edge of the book until the object begins to slide down.• Measure the height of the book edge above the tabletop.• Now cover the book with a rough material such as sandpaper or fabric and repeat the test.

The higher the edge of the book needs to be lifted before the object slides down the greater the frictionresisting movement.


SOME MORE ABOUT MACHINES

Machines and energy are like chicken and champagneThere are things in this life that always go together, such as pepper and salt, meat pie and sauce, andof course, politicians and promises. You can add to that list machines and energy. What is this con-nection?If you refer to a science book you will find that it defines energy as, the capacity of a body for doingwork. If there is a connection between energy and work then there is a connection between machinesand work. Remember the Macquarie definition, machines are used in the performance of some kindof work.Energy is a vital element in any study of technology but quite often it is overlooked. Before wecontinue to explore the energy - machine connection we should establish a few things about energyitself.

1. Energy cannot be created or destroyedWhen people talk about an energy shortage they show their ignorance because energy cannot becreated or destroyed. Whatever happens we will always have the same amount of energy. The scien-tists refer to this principle as the conservation of energy.

2. Energy comes from a number of natural sourcesThe most important sources of energy are the sun, wind, water, food, fossil fuels (oil and coal),nuclear materials and the heat from the earth’s core.

3. Energy exists in a number of formsEnergy from natural sources is usually not very useful in meeting our needs unless we can change itin some way. In technology it is convenient to think of energy as existing in different useful forms.There is heat energy, mechanical energy (moving parts), electrical energy, sound energy, chemicalenergy and light energy.

4. Energy can be converted from one form to anotherWhile we cannot create or destroy energy we often need to change it from one form to another. Forexample, we cannot move a pile of rubbish and take it to the local tip using just heat energy, but if weuse an internal combustion engine to convert the heat energy into mechanical energy the load can betaken on a truck. Electromagnetic energy cannot saw a piece of timber, but an electric motor willconvert it into mechanical energy that powers the saw.

5. Energy cannot be seenUnless you have an out-of-this-world experience you will never see energy, but you certainly knowwhen it is around. When you feel heat, hear sound, see light or notice movement you know thatenergy is at work.

Machines as energy convertersThe most common use of machines is to convert one form of energy intoanother. Two examples illustrate this point.

• The chemical energy of the petrol is converted by an internal combustionengine in the lawn mower into the mechanical energy of the rotating blades.

• Electrical energy is converted into mechanical energy by electric motors.

Think of all the machines that have internal combustion engines and electricmotors. Of course other mechanisms are added to the end of the engines andmotors to perform a wide range of work.

In a machine it is the energy of the moving parts that does the work, therefore energy must be one isone of the most important outputs. Petrol and electricity are sometimes referred to as ‘energy carri-ers’ because they carry the energy to the machine where it is put to use, and this makes them idealinputs.


Machines and societyNow its time to look at the relationship between people and the machines they use. We all know ofsomeone who loves their car more than any person, but this is not the type of relationship we aregoing to look at.Throughout the centuries machines have had a big impact on the fortunes of the people who usedthem. Some examples will prove this point.

• Bows and arrows extended the hunters capability to provide food and defend themselves.• The wheel and axle may be one of the simplest but most important discoveries. Imagine world

without wheels.• The windmill and waterwheel allowed the energy of the wind and flowing water to be har-

nessed and used to power machines. Remember that machines make it possible to do morework.

• Steam engines were first used to pump water out of mines and so allow access to the coal thatwas found at deeper levels. The chemical energy of the coal was then used as the input forsteam engines.

• Factories replaced cottages as the places where things were made. Steam power made it pos-sible to drive the new machines that were needed to produce a range of goods.

• Steam was also used to power the trains and ships that transported all the products from thefactories to the consumer.

• Machines were built that would cut and shape iron and steel; therefore all sorts of other ma-chines could be made.

• The Industrial Revolution was possible because of the power of steam and the machines thatproduced goods that were cheaper and available to a wider range of customers.

• The internal combustion engine changed forever our concept of space and time. The car wasresponsible for our mobile society.

• Electricity and electric motors now power machines in factories, offices and homes. The en-ergy needed to operate machines is carried along wires that take it to almost any place in ourcountry.

Machines and the environmentMachines require energy to make them work. In Victoria the major source of energy comes fromfossil fuels. Coal is used to generate electricity and oil based fuels provide the petrol and diesel topower a whole range of machines. The use of fossil fuels creates many environmental problems; themost urgent one is the air pollution caused when such fuels are burnt.Another environmental problem is the eager-beaver neighbour who starts up their mower under yourwindow early on Sunday morning . The degree of noise pollution is subjective as it often depends onwhat you did on Saturday night.

How to communicate with your machinesPeople who have lots of experience learn to understand the signals machines use to communicatewith those who use them. Squeaks, screeches, rattles, clanks and thuds all have their own particularmessage and it is usually a warning of bad news. Like cats that purr when everything is going well,machines have their own version of the ‘good news sound’, usually a contented whirr or buzz. Ignorea machine’s warning signal and you will usually pay dearly. Listen to your car or washing machineand over a period of time you will learn its signals.Joe, my friendly motor mechanic asked me to include this bit because he gets angry when people callhim and say ‘It won’t go.’ After some questioning he finds that over a period of time the car tried totell the driver that something was wrong; first with a little rattle, then a few louder clunks, and finallya deafening thud and silence. Be kind to your machines and listen to them.

LEVERS

This unit focuses on levers, one of the very common and useful simple machines. There is lots ofinformation in the Content part of this section. Keep reading and you will become the leading leverguru in your school. Well, at least in your classroom.


1B: THE DESIGN BRIEF

One of the really good uses of technology has been in helping people with disabilities. There arewheel chairs, artificial limbs, glasses and hearing aids. There are also some people who are old orhave a disability find it difficult to bend their back or legs therefore they have trouble picking thingsup from the floor or ground. Perhaps technology can help them.

Your taskYou are asked to design and build a working model of a mechanism that will enable people to pickup objects on the floor without bending.

Things to think aboutThe mechanism must:

• be able to pick up objects of different shapes and sizes.• grip the object so that it does not fall while it is being picked up.• be sturdy.• be simple to use.• be cheap to make.• use levers.

Materials to be usedThe main material will be stiff cardboard plus any other materials that you find around your homeand school. Other things like rubber bands, icypole sticks, masking tape and odd bits and pieces mayalso be used.

EvaluationThe model you make must be capable of picking up an object such as a fork or spoon.

Use the information in, ‘How the engineers would approach the prob-lem’, to start the students thinking about a range of possibilities. Theuse of cardboard working models is a legitimate strategy used by en-gineers as they work on solving problems. Remember that all the pointsin the curriculum focus statements in each phase describe the contentin terms of knowledge and skill, therefore select carefully from thesuggestions below.

WHAT YOU NEED FOR THIS UNIT

You will need to speak nicely to your local supermarket manager to get some cardboard boxes. Thenyou collect bits of string, masking tape, stapler, glue, scissors, Stanley-type knives (they are forteachers use only) and steel safety rules for guiding the blade, 300 mm ruler and pencil, one holepunch, letter fasteners, drinking straws and florist’s wire. If you have access to suitable pieces ofwood and the tools to cut and drill then make use of them.

CAUTION

PROCEED WITH

EXTREME CARE


1C: WHAT HAPPENS IN THE FOUR PHASES?

If you have not read the warning at the start of this section please do so now. This is a list of suggestedactivities for each phase. The key word is SUGGESTED.

InvestigatingThe list of topics below would be suitable for this unit:

• Investigate the people who design and build machines. Who are these people? What type ofmachines do they design and build?

• Make a list of machines that have been designed to help people with disabilities, and explainhow these machines have assisted the user to lead a better life. Artificial limbs and wheel-chairs are examples of simple machines.

• Select a machine and begin exploring how using it will have an impact on the environment in the localcommunity. The impact could be negative (pollution or waste energy) or positive (reduce or eliminatepollution, or conserve energy). Pollution takes many forms: air, water, soil, noise, visual, etc.

• Conduct tests to discover the effect of changing processes on the output. Consider the lever tobe a process that converts the input into the output. The testing procedure described in Section3 can be used on a variety of levers and situations (Section 1).

• A number of machines that we use today have electric motors to provide the power to make themwork. In earlier years some of these machines were operated by human power; people pushed,pulled, turned and twisted levers and handles to make them work. Make a list of these machinesand describe how people operated them before electric motors were used. The addition of theelectric motor means that there are two systems. One is the electric motor to convert the electri-cal energy into kinetic energy, and the other the mechanism to give us the desired output, such asrotating beaters on a food mixer or the backwards and forwards motion of an electric knife.

DesigningDuring this phase the students should have the opportunity to demonstrate the following:

• Present at least two design options exploring alternative combinations of levers and linkages• Select one of the design options as the preferred choice and give reasons to support that choice.• Develop appropriate ways to test the performance of their solution.• Even though this is a cardboard model or prototype, the design could examine the use of a

battery-powered mechanism.• Suggest suitable materials for the real product and give reasons for the selection.

ProducingIn this phase students should have the opportunity to demonstrate the following:

• Use a range of tools, equipment (such as scissors, hole punch, ruler, and stapler) and materialssafely and correctly.

• Construct their systems to achieve design requirements as outlined in the design brief.• Modify construction techniques where necessary to improve quality and presentation. This in-

cludes the ability to make changes during the actual construction if problems are experienced.• Maintain the equipment they use. This includes recognising faults and correct storage procedures.

EvaluatingTo achieve this level a student will have to be able to cover the following:

• Evaluate the performance of their systems against the design requirements set out in the de-sign brief, and use testing methods they have devised in the design phase.

• Comment on their success in efficiently using time, materials and other resources. Efficiencyis a measure of success in reducing waste to a minimum.

• Present reports taking into account some environmental implications, such as using materialsthat can be recycled or reducing the amount of energy needed to operate the device.

• Present reports in oral, written and graphic form.

The Assessment section shows how these activities and expectations are linked tooutcomes for Level 4 in Systems.


12

6

9 3

1D: TECHNICAL KNOWLEDGE AND SKILL CONTENT

The table below contains an outline of the knowledge and skills related to solving the problem in the design brief.Read all this section for your own benefit, and then select carefully what you want to teach your students. What youteach will depend on things such as, your level of confidence, the ability of the students to learn, and, of course, thetime available.

KNOWLEDGE AND SKILL EXPLANATION

MECHANICAL ENGINEERING

Mechanical engineering turns energy into power and motion. Mechanisms (machines, tools and equip-ment) are designed, produced, tested and improved by mechanical engineering teams. They usuallywork for industry, designing systems and machinery that generate power, makeproducts (often using robotics that imitate human movements), move things(forklifts, trucks, helicopters) and help in building (cranes, lifts). Peopleworking in this area also create and improve machinery that we use inour homes (refrigerators, hair dryers, toasters) and in public (trains,turnstiles, etc.).The mechanical area has close links with other areas,and applies knowledge of materials, energy and structures.(Engineering Careers Information, Institution of Engineers, Australia)

Section 2: The Engineers, provides more detailed information.

MACHINES

‘Machines’ is a name given to category of things made by people. A machine can be described assomething that:

• allows us to do all sorts of work quicker, safer and better• saves us time and energy• is made up a number of parts connected in a particular way• has parts that move

Here are two examples of common machines:

A bulldozer can dig a hole easier and quicker than youcould using your hands, or even a shovel. The watchallows you to tell the time more accurately than youcould using only the sun.

MECHANISM

Mechanism is another name for a machine. In this unit it will be used to describe examples of verysimple or basic machines.

MACHINES AND MATHEMATICS

Mathematics is also used to help us understand the world of machines. Engineers use it to assist themin their design work. Mathematics can describe how a machine will perform under certain conditionseven before it is made.

MACHINES AND SCIENCE

Science plays an important role in helping us understand machines. The study of things related tomachines is called applied mechanics, which in turn is part of the field of science know as physics.There are a number of words we use every day that have very specific meanings when we talk aboutmachines. For example, energy, force, work and power.



ENERGY

Energy is the capability to do work. Just as people need energy to do work, so do machines. There arefour important things to know about energy.

• Energy cannot be created or destroyed. This is known as the principle of the conservation ofenergy.

• Energy comes from a number of natural sources, and the most important are the sun, wind,water, food, fossil fuels (oil and coal), nuclear materials and the heat from the earth’s core.

• In technology it is convenient to think of energy as existing in different useful forms. There ischemical energy, heat energy mechanical energy (moving parts), electrical energy, sound en-ergy and light energy.

• While energy cannot be created or destroyed we often need to change it from one form to another.

FORMS OF ENERGY

Chemical energyThe substances we know as fuels are examples of chemical energy. For example, petrol, dieseloil, liquid petroleum gas, coal and natural gas release energy when they are burnt. The chemicalcomposition of the substance allows energy to be stored and then released when required. Forexample, petrol can be carried in tankers or drums to where it is needed.

Heat energyThis is a most important form of energy because it is used to heat ourhomes and work places, and to cook our food. It is also the form of

energy that we use to make many machines work. Brown coal is burnt todrive the generators that supply our electricity; petrol is burnt in the internalcombustion engines of cars, trucks and lawn mowers; and kerosene is burnt injet engines. This heat energy is then used to make the parts move.

Mechanical energyScience describes two forms of energy associated with machines – kinetic energy and potential en-ergy. Before you throw your hands up in horror, read on. The explanation is really quite simple.

Kinetic energyAll moving bodies (science talk for an object) have kinetic energy. The amount of energy is related tothe mass (you might like to think of it as the weight) of the object, and the velocity (the non-scientistusually refers to this as the speed). The two examples below explain this in simple terms.

• A small car travelling at 100 kilometers per hour (kph)has less kinetic energy than a larger car traveling at thesame speed.

• A car travelling at 100 kph has more kinetic energythan the same car traveling at a slower speed.

The amount of kinetic energy is controlled by the mass(weight) and speed (velocity).



FORMS OF ENERGY (CONT.)

Potential energyThis is often referred to as stored energy. A body is said to have potential energy because of itsposition or state. It is often referred to as stored energy, and a couple of examples will illustrate this.

• When you pick up a six pack of Coca-Cola from the floor and put it on a table the energyyou have used is ‘stored’ because of its position. If the table was removed gravity

would return the pack to the floor.• A spring that is stretched or squashed has potential energy because of its state ofbeing stretched or squashed. The energy you used to stretch or squash it is storedready to be released when the spring is allowed to return to its original position.Once the object begins to move it has kinetic energy. For example, an archer useskinetic and potential energy when shooting an arrow. The archer uses energy todraw the bow string back and while holding the arrow ready to fire the bow pos-

sesses potential energy that is released when the arrow is released. The kinetic enrgy of the movingarrow carries it to the target. Engineers who design and build machines are very interested in bothkinetic and potential energy

Sound and light energyEnergy is needed to produce sound and light. These forms of energy are not that important when youwork with machines.

FORCE

Force is a word we often use to describe something that influences the way we behave. ‘I was forcedto use the ATM when I ran out of cash.’ In technology force is one of the words that has a specificmeaning.The ancient Greeks such as Archemedes were very interested in understanding the world in whichthey lived. Over the centuries the interest has been maintained and in 1687 Isaac Newton publishedhis now famous laws of motion that explained how and why things move. These laws are still used byscientists and engineers.In science and engineering a force is a push or pull that results in one or more of the following.

• Makes a body move. A force applied by a golf club makes the golf ball move rapidly straightdown the fairway (well that’s the theory anyway).

• Increases the velocity of a body. If you are riding your bicycle the force of a sudden gust ofwind from behind will increase your speed.

• Reduces the velocity of a body. If you ride your bicycle into a head wind the force will reduceyour speed.

• Changes the direction of movement. You are driving your car along a straight road whensomeone not stopping at a stop sign hits you in the side. The force applied by the other carsends you off in another direction.



GRAPHICAL DESCRIPTION OF A FORCE

To describe a force you need to give some details. You can show a force on a drawing by using anarrow. This is the method used in technical books.

• You can show whether it is a push or a pull.

• You can show the size of the force. A longer arrow indicates a larger force.

• You can show where it is applied

• You can show the direction of the force.

WORK

Worldly, experienced adults understand work as something you do to earn money, and also the other stuffyou do at home such as housework or gardening. Once again science has its own very specific definition.

Work is done when a force is applied to a body and the body moves in the direction of the force.

Remember that the term body has nothing to do with Tom Cruise or Elle MacPherson. A body is anobject of some sort. Work is done when you push or pull an object and it moves in the direction youpushed or pulled.The definition of work sometimes causes confusion because we should talk about the amount of workdone on a body (object) when it is moved by a force. For example, someone has a car that will notstart and they ask you to push it into the gutter out of the traffic. You apply a force (push the car) butit does not move because they left the handbrake on. In science you have applied a force but no workwas done because the car did not move. After you have sworn at the driver and the handbrake isreleased you apply the force and the car moves. Now you have done work on the car.

POWER

Power is the rate of doing work. In other words it is how much work is done in a certain period of time.• A semi-trailer can do more work than a small truck therefore it is more powerful• Industrial quality sewing machines are more powerful than their domestic counterparts.

Power is a way of comparing machines. In the Industrial Revolution people realised that they neededsome way of comparing the new machines with the older, but still popular, sources of energy. Horseswere still used for many tasks and James Watt (of steam engine fame) worked out that one horsecould lift a weight of 550 pounds (250 kg) a distance of one foot (30 centimetres) in one second. Thisbecame known as one horsepower (usually written as hp) and it became the standard for measuringand comparing power. Today some car people still talk about horsepower when referring to the en-gine, and airconditioners are still advertised using the abbreviation hp.In the metric system we use watts as the unit of power so next time you by an electric appliance suchas a vacuum cleaner or electric drill check on the power rating. The more watts, the more powerfulthe machine.

è èPUSH PULL

è è

èPUSH TOTHE RIGHTAT THE TOP ç

PUSH TO THELEFT AT THE

BOTTOM

è

èè



ÝÝ

Ý

THE WAYS PARTS MOVE IN A MACHINE

The ways parts move in a machine is always of interest to those who design them. One of the thingswe use machines for is to change one type of motion into another. To make some sense out of this weneed to describe the different ways that things move and we use the following words.

• Linear• Reciprocating• Rotary• Oscillating• Random

In the explanations below a line and the direction show the path that the part follows by an arrow.

Linear motionIf something moves in a straight line the motion is described as linear. The movement can be to theleft or right, in or out, up or down and at an angle to something.

Examples include a ball dropped from your hand, hot rods racing, the tray to hold the disc on a CDplayer and marbles rolling down a slope.

Reciprocating motionThere are machines where the output is a part that moves backwards and forwards or up and downcontinuously. The distance moved usually remains the same. This is called reciprocating motion.

The blades in an electric knife and the needle on a sewing machine are examples of reciprocating motion.

Rotary motionRotary motion describes things that go round and round.It is usually described as clockwise or anti-clockwise(sometimes called counter-clockwise).Wheels are examples of rotary motion; so are hands on clocksand parts in video and audio recorders that wind the tapes in the cassettes.

Oscillating motionWhen things swing back and forth this is called oscillating motion. Like reciprocating motion thelength of the swing often stays the same.

The movement of a pendulum on a clock or a child on swing could be described as oscillating motion.

Random motionSometimes an object moves all over the place without any control.Examples of random motion include a piece of paper caught in a gust of wind or a balloon you blowup and then let go.

Ý

Ý Ý



SYSTEMS

Chambers Science and Technology Dictionary is a reputable source of technical information, and itdefines systems as:

Generally anything formed of parts placed together or adjusted into a regular or connectedwhole.

Machines fit nicely into this definition. They are made up of a number of parts connected in a specificway, and we treat them as one unit. For example, you think of your washing machine as a single entityrather than a collection of parts.

The CSF describes a system in the following way.• Systems are combinations of human and technical elements that work together to achieve

specified outcomes.• Each system contains separate parts or elements connected in a specific way to make the

system work.• Technological systems have particular inputs, processes and outputs controlled by people.

Combinations of human and technical elementsPeople such as mechanical engineers are responsible for designing and building machines. People arealso involved in the operation of the system. They may set the controls and start up automatic systemsthat then operate without further intervention. People may also be part of the ongoing operation, suchas the driver of a car who must continually monitor speed and direction and make adjustments whenrequired.

Parts connected in a specific wayNo one would argue that machines are just parts randomly connected. A loose wire or a missingscrew can convert your car into a useless pile of junk that just sits at the kerb.

Inputs, processes and outputsEvery system can be described by its input, process and output. In simple language we us a systemsuch as a machine to convert an input into something else that we call an output.

INPUT-PROCESS-OUTPUT

Some examples may help to make this clear.• Your hair is wet and you need to dry it quickly. A hair dryer would be useful but only if it is

plugged in and switched on. The dryer converts the electrical energy into heat energy andkinetic energy of the hot air blasting out of the nozzle. What ever is inside the dryer hasprocessed the electrical energy at the input and changed it into a hot air blast at the output.

• Your motor mower is just a collection of bits andpieces until you put in the fuel and start it up. Themower has processed the fuel and changed it into arotating cord that cuts the grass.

• You turn the knob on the door lock and the bolt moves in and out. The lock has converted onetype of movement into another. The door lock has processed the turning motion into what iscalled reciprocating (back and forward) motion of the bolt.



SYSTEMS DIAGRAM

Technology gurus use a simple diagram to describe a system, known as the universal systems diagram.

INPUT ð PROCESS ð OUTPUT

We can now use this to describe a hair dryer.

ELECTRICITY ð HAIR DRYER ð BLAST OF HOT AIR

This is good enough for your first attempt, but when you become an ‘expert’ you will be able toproduce diagrams like the one below.

ELECTRICAL ENERGY ð ð

BLACK BOX APPROACH

One useful way of approaching a systems problem is to use the ‘black box’ approach. ‘Black box’ isa colloquial term for an electronic unit that is ‘hidden’ inside a box, not necessarily black. You mayread of an aircraft crash that they are looking for the ‘black box’ which is the flight recorder. The‘black box’ approach is often used in systems work. It means that you don’t concern yourself withwhat goes on inside the black box (the machine or electronic device) but concentrate on the input andoutput.

You think of the system itself as a black box and the examples below illustrate this idea. You canthink of inputs and outputs in many ways, such as motion, energy and materials.The system that raises and lowers your rotary clothes line. The input is the rotary motion of thehandle and the output is linear motion (up or down) of the clothesline.

A motor mower is a system that converts the chemical energy stored in the petrol into the mechanicalenergy of the rotating blades.

A food mixer is a system that converts all the individual materials (ingredients) into a new form (cakemixture).

Thinking only in terms of the input and output is a good starting point to understand systems. Studentscatch on very quickly. A system may have more than one input and output.

IS CONVERTED BYTHE ELECTRICMOTOR AND

HEATING ELEMENT

INTO HEAT ENERGYAND THE KINETICENERGY OF THE

MOVING AIR

OUTPUT

èèINPUT

MECHANICAL ENERGY OFTHE CUTTING BLADES

CHEMICAL ENERGYIN THE PETROL ð ð

THE CAKE MIXED READYFOR THE OVEN

INGREDIENTS FORTHE CAKE ð ð

THE LINE IS RAISEDOR LOWERED

TURN THEHANDLE ð ð



BLACK BOX APPROACH (CONT.)

A toaster converts:• electrical energy into heat energy (element)• bread into toast (materials)

A food blender converts:• electrical energy into mechanical energy (cutting blades)• a large piece of vegetable into small pieces (materials)

An electric fan converts:• electrical energy into mechanical energy (rotating blades)• still air into moving air (motion)

The most important concept here is to think of a system as a thing that converts something intosomething else. It does not sound very technical but it is important.

SIMPLE MACHINES

There are some very basic machines that have been around for centuries and they are known as‘simple machines’. The best known are the:

• inclined plane;• pulley;• screw; and• lever.

Refer back to the Background Information at the beginning of this section for some examples.Even the bigger more complex machines are made up of combinations of simple machines.

LEVERS

Everyone knows that a screwdriver is the ideal tool to get the lid off a can of paint. Your dentist usesa pair of pliers to pull those aching teeth out, especially the ones that stop hurting as soon as you enterthe waiting room. Successful casino patrons who know about levers would use a wheelbarrow to taketheir winnings to the bank.

MORE ABOUT LEVERS

A lever is a rigid bar that is free to rotate about a fixed point called a fulcrum. Simple levers arestraight bars, but they can be bent in different ways. Simple levers are often shown in textbooks assomething that resembles a seesaw.

Levers are not used for their aesthetic qualities. They are there to help us do work easier, quicker and/or better. Converting a small force into a larger one

People, including teachers, like to do as much work as possible with the least amount of effort. If youthink this is a good idea then levers are for you.

You childhood experiences on the seesaw will prove invaluable as you learn about levers. If youmissed out on this experince you need to get a friend, go to the local playground and make up for losttime.

FULCRUM

RIGID BAR



MORE ABOUT LEVERS (CONT.)

Sometimes the seesaw is evenly balanced.

This occurs when the load (weight) is the same at each end and is the same distance from the fulcrum.What happens when this is changed?If the load stays the same but one is moved closer to the fulcrum you know from experience that theseesaw will look like the one below.

If the load at one end is smaller than the one at the other end, although both are the same distancefrom they fulcrum, you know what will happen.

If you are beginning to suspect that equiibrium (eevenly balanced) has something to do with the loadand distance from the fulcrum, then you are spot on. Simple, isn’t it.If you have kept up with all this lever information to this point then you are ready to mover on to somereal technical stuff.



LEVERS AND MATHEMATICS

A few centuries ago (around late 16th and early 17th centuries) the Italian scientist Galileo Galilei wasone of the first to use mathematics to describe what happens in nature. After his lever experiments hefound that a lever would be in equilibrium (science talk for evenly balanced) when the load multi-plied by its distance from the fulcrum was equal for both sides.

The lever is equally balanced because:Weight of Junior x Distance A = Weight of Mum x Distance BWe measure the distance from the middle of the elephant because in technology we assume that theweight of an object acts through its centre of gravity, and with elephants it is somewhere between thefront and back legs. If you want more accurate details get an elephant and experiment.Of course if Junior put on a bit more weight all this equilibrium thing would be upset and he/shecould actually lift Mum. Imagine the following scene.Junior and Mum are on the seesaw and it is in equilibrium (evenly balanced). Junior jumps off andMum crashes to the ground.

Junior eats a few tasty pieces of whatever elephants eat and as a result adds a few centimetres to thewaistline. If Junior now jumps back on the seesaw Mum is lifted to new heights all because heroffspring has put on a couple of kilos. All this proves that a small elephant (or effort) can move alarger elephant (or load).



LEVERS AND MATHEMATICS (CONT.)

The words effort and load are important when we talk about these simple machines. In systemslanguage the effort is the input and the load the output, and in textbooks they do not usually useelephants as symbols. If you push or pull a lever to make it work you are applying a force and this canbe shown by an arrow.

In the 3rd century BC, Archemedes, a famous mathematician, was reported as saying, ‘Give me alever long enough and a place to stand and I will move the earth.’ Theoretically speaking it is possibleto have a seesaw in equilibrium with an elephant at one end and a mouse at the other. Of course youwould need a lever a couple of hundred kilometres long.

There�s no such thing as a free lunch or lift on a seesaw.You might be able to convert a small force at the effort into a larger one to move a heavy load butthere is a cost involved. Before you read on, take a break, make a cuppa and refer back to the part onforce and work.You would remember that work is done when a force moves a body, and no work is done if the bodydoes not move. Well, nature likes to have everything nicely balanced and if you do work on one endof a lever it has to be balanced by work done on the other end.If you recall the small and large elephant example the explanation goes something like this.The effort (Junior) is smaller than the load (Mum) and further away from the fulcrum. When the lever(seesaw) moves the effort will travel further than the load. In mathematical language it looks likethis.Effort x distance the effort moves = Load x distance the load moves.In plain English it means a smaller force can be used to move a heavier load but it must travel alonger distance.

MECHANICAL ADVANTAGE

Engineers can compare machines by looking at their Mechanical Advantage, commonly known asMA. Once again we resort to mathematics to help with this comparison. It is just the ratio of the effortto the load and it is written as:

Mechanical advantage LoadEffort

=

In the elephant example, if Mum weighs 1000kg and Junior 200kg the MA would be;

1000

2005=

As you can see the larger the MA the more efficient the machine. In other words a smaller effort willmove a larger load. If you want to be a real tech-head you would say, ‘The MA is 5.’



VELOCITY RATIO

You can also describe the distance moved by the effort and load using mathematics. This time youcompare the distance moved by the effort and the distance moved by the load, and this is called theVelocity Ratio, generally referred to as the VR.

Velocity ratio Distance moved by the effort

Distance moved by the load=

In a perfect machine the MA should equal the VR but you should know by now that nothing isperfect. You will understand all this when you get to the section on friction.

CLASSES OF LEVERS

Primary teachers are into classification; therefore you should love levers because they can be dividedinto three classes. It is all to do with the position of the effort, load and fulcrum.

First class leversThis is the most obvious form of lever where the fulcrum is between the effort and the load.

Examples include: seesaws, hammers pulling out nails, crowbars, twowheel trolleys, handbrake levers and using a screwdriver to open a canof paint. Scissors are an example of two first class levers that share thesame fulcrum.

Second class leversIn this class the load is between the effort and the fulcrum.

Examples include the wheelbarrow.



CLASSES OF LEVERS

Third class leversWith this class the effort is between the load and the fulcrum.

Examples include barbeque tongs and tweezers.

Think about a strawbroom; you use one hand to hold it still at the top and the other hand pushes thebroom somewhere along the handle. Of course the dirt you sweep up is the load.

DRAWING LEVERS

You have learnt how to show a force on a drawing. Now it is time to look at a couple of ways to drawlevers because they all don’t look like seesaws.The first method is to draw them as rigid bars that rotate around a fulcrum that is something like anaxle.

The second method is known as schematic drawing where you use A line for the lever and a dot forthe fulcrum.

CHANGING THE DIRECTION OF MOVEMENT

One of the really useful things that levers can do is change the direction of movement. In the commonstraight lever you push down on one end and the other goes up, or if you live in the northern hemi-sphere you push one end up and the other goes down. If the lever is vertical you push the top to the leftand the bottom moves to the right, and so on. With straight levers the forces at the effort A and loadB are parallel.

FULCRUM

FULCRUM

è

è

èA

è

B



CHANGING THE DIRECTION OF MOVEMENT (CONT.)

Because levers are very versatile machines they come in many shapes and sizes and some are knownas bell crank levers. They got their name from those dinky little bells that were used to summonservants when there were such people.When you use bell crank levers the forces at the effort and load are non-parallel; therefore they givedesigners lots of options.

If you want to get really fancy you can move two loads with one effort. You apply the effort at A andyou are able to move loads at B and C.

LEVERS AND SYSTEMS DIAGRAMS

If you have read all about systems and levers you would have immediately integrated all the informa-tion and considered producing a couple of systems diagrams like those below.

and

OUTPUT INTO MOVEMENTIN ANOTHER DIRECTION

AT THE LOAD

INPUT MOVEMENTIN ONE DIRECTION

AT THE EFFORT ð ðPROCESS IS CONVERTED

BY THE LEVER

èA

B

è

Cè

èA

B è

èA

Bè

OUTPUT INTO A LARGERFORCE AT THE LOAD

INPUT SMALL EFFORTAT THE LEVER ð ðPROCESS IS CONVERTED

BY THE LEVER



LINKAGES

So far you have been working with a single lever but you can also use combinations of levers. To dothis you use rigid bars known as linkages. Some examples are shown below.The moveable joint is not a fulcrum. A fulcrum does not move from its set position, unlike the move-able joints that move as the linkage and/or lever moves.

Two levers moving in the same direction

Two levers moving in opposite directions

AlternativesThe guides are necessary to keep the linkage in place as it moves backwards and forwards.

Sometimes the linkages look different, for example a piece of stiff wire. Remember that it is still arigid bar.

Refer to Section 3 for hints on testing levers.

è

è

WIRE

è

GUIDE

è

è

è

è

MOVEABLE JOINTS

è

è

LINKAGE

èè

è

GUIDES



YOU NEED FRICTION HERE ANDHERE TO MAKE THE BIKE MOVE

YOU NEED FRICTION HERE AT THEBRAKES TO MAKE THE BICYCLE STOP(IF THEY’RE HAND OPERATED FROM

THE HANDLE BARS

AND YOU REDUCEFRICTION HERE

YOU REDUCEFRICTION HERE

CABLES

Sometimes you can connect levers and linkages using cables. A cable is a flexible length of material,such as a piece of string or cord. The problem with most cables is that you can pull them but not pushthem. Try using string instead of wire in the example above and observe the difference.

FRICTION

Quite often you will hear someone talking about friction between two people, and what they mean isthere is a conflict of views or opinions. In science, engineering and technology friction has a veryspecific meaning. It is the resistance to movement when two surfaces slide over each other. Someexamples will help.

• If you drag a heavy box of books across the floor the friction between the bottom of the boxand the floor resists the movement and makes your task harder. In other words you have toapply a larger force (pull) to get the box moving.

• Basketball players wear shoes with rubber soles to get a grip on the floor. The friction be-tween the sole and the floor resists movement and helps prevent slipping.

Engineers have a love-hate relationship with friction; it can be a friend or foe.

Friction as a friendThere are times when you need to eliminate or reduce slipping between two surfaces. When you driveyour car the tyres should grip the road otherwise you find it hard to get going, steer and stop. If youget the chance to play in the Australian Tennis Championship at Melbourne Park make sure the solesof your shoes will not slip on the Rebound Ace surface. If you look under the bonnet of your car youwill see pulleys (wheels with a groove around the outside) connected by a belt. If the belt does notgrip and turn the pulleys you are in real trouble; you will soon have a flat battery, the engine wouldoverheat, and the air-conditioner would not work.

Friction as a foeIf friction resists movement of one surface over another then the force you apply must not only belarge enough to move the object but also to overcome the friction. Friction also generates heat andthis is a real problem for people who design machines. Sometimes the heat is so great that things meltor they expand and seize up. Seizing up occurs when two parts fit snugly together, such as an axle ina wheel, and friction reaches a point where the heat causes the axle to expand faster than the wheel itjams tight and everything comes to a sudden stop. Remember that a machine has moving parts and theeasier it is to get the parts moving the less energy we use.



FRICTION (CONT.)

Reducing frictionThere are two ways to reduce friction.

• The smoother you make the two surfaces the less friction you will have. It is easier to slidesomething over a smooth sheet of glass than it is over a piece of sandpaper. Engineers will tryto get surfaces that slide over each as smooth as possible. Smooth and shiny floor surfacessuch as some tiles are often slippery because there is reduced friction.

• Separating the surfaces with some slippery substance also reduces friction. Standing on thesoap in the shower is not recommended because soap is a slippery substance. Wet roads arealso a hazard because the water tends to get between the tyre and the road. Engineers uselubricants such as oil and grease to reduce friction. Now you know why it is important tocheck the oil level in you car at regular intervals.

Refer to section 3 for some ideas on testing friction.

FOUR BAR LINKAGES

One of the really interesting linkages is known as a four bar linkage, probably because it has fourbars. One example is when the four bars form a parallelogram.

A feature of this linkage is that the opposite sides always stay parallel as it is opened and closed.

One use for this type of linkage is the scissors lift that workers use to reach high places such asceilings in large buildings.



CONSTRUCTION TECHNIQUES

The model can be made of cardboard and the list below outlines some of the techniques that could beused in the construction.

Levers and linkagesStrips of stiff cardboard make useful levers and linkages. Where a linkage has to slide back and forththe guides can be made as shown below. Make distance ‘X’ slightly larger than the width of thelinkage, and the sheet of paper between the same thickness cardboard as the linkage will provide aguide that allows the linkage to move easily.

Permanent joinsThere are a range of processes that include staples, adhesives and sticky or masking tape.

Fulcrums and moveable jointsThe holes for the fulcrum and/or moveable joints can be produced with a single hole punch. Letterfasteners can be used as the fulcrum or to connect linkages.

LinkagesIn addition to the cardboard linkages you can use florist’s wire and the guides are pieces of drinkingstraws.

CARDBOARD

DISTANCE ‘X’PAPER

→

→


Section 2: THE ENGINEERS

2A: PAUL

Paul is a mechanical engineer. While hewas at primary and secondary school hewas always interested in tinkering withthings, and it was no surprise when hechose to study Mechanical Engineering atMelbourne University. Mechanical engi-neers work as a team to design, build, testand improve machines. The machines arethings with moving parts and they may beas small as a wristwatch or as large asjumbo jet. Without mechanical engineersthere would be no cars, washing machines,cranes, drink-can machines, lifts and es-calators, dentists’ drills, video recordersand hundreds of other machines we useevery day. When Paul was studying forhis degree he was also very interested inmusic. He taught the clarinet, played for small theatrical productions, and was member of the Mel-bourne Youth Symphonic Band. Today he is less interested in music and spends his spare time surf-ing, building things at home, and being with his wife and children.

What sort of work does Paul do?Since he finished his engineering studies Paul has worked as a mechanical engineer at a number ofdifferent companies. One produced oil, another food and a third made life saving drugs and medicine.In each place Paul was responsible for the machines that were used to make the oil, food and medi-cines. One of his most interesting projects was to design and help in the building and installation ofmachines at one of Australia’s well-known chocolate makers. The machines were used to makechocolate products, such as Easter eggs.Engineers work as teams and now Paul is in charge of a group and together they work at solvingproblems for people called clients. To work as a mechanical engineer you have to spend time usingmathematics to do calculations, understand how different materials can be used, and use your knowl-edge of science to think of ways to solve problems. Paul and his team would use computers to helpthem with their work. Mechanical engineers use drawings to describe their design ideas and to com-municate with other people.Many mechanical engineers like Paul spend years gaining experince and this allows them to becomeconsulting engineers. There are many companies that might not have a mechanical engineer workingfor them so when they do have a problem they call in people who can help them solve problems. Paulwent back to study at Deakin University to learn how to become a better manager.

What does Paul like about his job?The part of the work that Paul enjoys most is working on lots of exciting projects at the same time. Heis kept busy talking to clients, going to meetings, and managing his group of engineers. Helpingpeople to solve problems is part of every engineer’s work and Paul and his team feel good when theyare successful. Being part of a team is also something that makes mechanical engineering an interest-ing career.


2B: BARBARA

Barbara is a Mechanical Engineer. She lives with her husband Mark, her young son Ethan and a catcalled Panther. Her hobbies are art and craft work, sewing, bush walking, rock climbing and playingsquash. She has also done some parachuting and Bungy jumping.At secondary school Barbara liked mathematics and science so she thought of studying Architectureat university. She changed her mind and started a degree course in Engineering, even though shedidn’t really know what an engineer did. After four years of study at Royal Melbourne Institute ofTechnology Barbara graduated as a Mechanical Engineer. In her last year she did a night course tostudy computers and how they are used to control pneumatic machines. These are machines that usecompressed air to make them work. Pneumatics is pronounced as ‘numatiks’.

What sort of work doesBarbara do?Barbara’s first job was de-signing, testing and install-ing pneumatic machines. Shealso had to write the softwareto be used in the computersthat controlled the machines.The machines she designedwere used to make lots of dif-ferent things such as cottonwool balls, ice-cream con-tainers, bike helmets andchocolates. Her biggest jobwas to work out how to con-trol the robot arm on the backof garbage trucks. This is thearm that picks up the garbagebins, tips them upside downto empty the rubbish and thenputs them back on theground.Barbara now works for a different company and she designs, tests and installs much bigger machines.She has worked on some very interesting projects. One of the projects was to design a test rig to testthe catalytic converters on cars. The catalytic converter is part of the exhaust pipes on cars and itreduces the amount of undesirable gases that pollute the environment. On another job she had tocalculate the amount of gas and oil that was being pumped out of an oilrig. To do this she had to takemany measurements and use lots of mathematics. To do all this work Barbara had to spend time on anoilrig at sea and she had to do helicopter safety training before she could fly out to the rig. Most of theprojects take 6 to 12 months to finish.Even though Barbara is a Mechanical Engineer she has also worked with electrical and chemicalengineers because some of the projects she has worked on need people who know about electrical andchemical things as well as machines. There are very few girls who study Mechanical Engineering.Only one other girl was in Barbara’s class at university. Women like Barbara have shown there is noreason why girls cannot become Mechanical engineers.

What does Barbara like about her job?Barbara really enjoys working as a Mechanical Engineer. She likes working in a team with otherpeople and feels that she is doing something that will improve the lives of lots of people. One part ofher work that she finds interesting is when she has to leave her office and visit the places where herdesigns will be used. Barbara is now a mother as well as an engineer and she finds both jobs veryrewarding.


Section 3: TECHNICAL RESOURCES

3A: SUGGESTIONS ON HOW TO SOLVE THE PROBLEM

Barbara and Paul were given the design brief and here are their suggestions for solving the problem.Once again you should use this list to select what you think would be useful.

INVESTIGATING

• Gather the range of objects that need to be picked up.• Carefully assess each object based on the following:• size• shape• feel• weight• Stand up and measure the distance from your hand to the floor to work out how long the

mechanism will need to be.• Consider the type of materials you will need - strong and rigid materials for the mechanism

and possibly softer materials that will provide a grip on the object to be picked up.

DESIGNING

• Think of the solution in two parts- the end that grips the object- the long piece that needs to span the distance from the object to your hands.

• Think of simple ideas first.• Be solution oriented, i.e. generate ideas rather than spending time analysing each idea• Think of other situations where you use something to pick up an object, such as:

- chop sticks- pliers- shovel

• Start drawing different mechanisms

PRODUCING

• Assemble the materials as shown in your drawing.• After each mechanism is built carry out a quick test on two different objects, one square and

the other round.• Refine the mechanism as a result of the tests, e.g. it may require a better grip, a longer shaft,

more strength, etc.• Don’t be afraid at this stage to start again with another mechanism rather than continuing with

one that simply does not work.

EVALUATING

• Use the mechanism to lift objects and ask the following questions.• How easy is it to lift the object? Define this on a scale of 1 to 10, with 1 being very difficult

and 10 being very easy.• How reliable is the mechanism? Pick up an object 20 times and define the result on a scale of

1 to 10, with 10 being very reliable and 1 being very unreliable.• How simple is the mechanism? Use a scale that ranges from 1 for complex to 3 for simple.• Develop other questions.• The highest score is the best mechanism.


3B: SOME SIMPLE AND EASY TESTS

You have two options: get the students to carry out the tests, or set them up yourself and let thestudents try them out. All you need is cardboard, drawing pins and letter fasteners.

Testing linkagesWhen testing levers and linkages you will need to use drawing pins for the fulcrum and letter fasten-ers for the moveable joints.

Testing combinations of leversThere are some combinations of levers and linkages that need guides to keep the linkage in its correctposition.

THICKCARDBOARD

DRAWING PINCARDBOARD

LEVER

FASTNER

DRAWING PIN

DRAWINGPIN

GUIDE

LETTERFASTNER


Comparing the size of the effort and the loadThis test is to demonstrate Galileo’s discovery. He discovered that the force multiplied by the dis-tance from the fulcrum is the same for each side of the lever if it is in equilibrium (evenly balanced).The mathematics was quite simple.Force at the effort x distance from the fulcrum = The force at the load x distance from the fulcrumTo demonstrate this you can use something like the set up below.

The lever is a strip of stiff cardboard about 450 millimetres long and 50 millimetres wide (you mayhave to tape two or more pices together to get a rigid bar. The fulcrum is a piece of wooden dowel ora round pencil. Use some ‘blue tack’ to stick the fulcrum across the lever at its centre point. The cupsare any very light plastic or polystyrene cups. For weights you need a number of identical items,marbles are very useful for this purpose.

• Use a pencil to mark the centre of the lever and also another 200 millimetres from the fulcrum.• Set up the test on a flat surface like a tabletop.• Place a number of weights into cup A.• Place cup B at the same distance from the fulcrum as cup A.• Now place the weights one by one into cup B until that end just begins to move downwards.• Compare the number of weights in each cup.

Repeat the test, but move cup B closer to the fulcrum, perhaps half way.The accuracy of the test may not be up to Australian Standards but it should prove that the closer cupB gets to the fulcrum the more weights you need to get the lever to move.Now that you have perfected the procedure you could put a set number of weights into cup B andplace it at different points along the lever. Now you can observe how many weights you need to put incup A to lift cup B. Compare the number of weights in each cup.This should prove the point that a small effort can be used to lift a heavier load.

CUP B

CUP A

MARKS

DISTANCE

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FRICTION TEST

This is a simple test to demonstrate the concept of friction as a resistance to movement. You need asolid flat surface, something about the size of an A4 sheet of paper will do. A hard cover book will bejust the thing. There are two tests.

Test 1

• Cover the top surface with a smooth material such as plastic film (Gladwrap is excellent).• Place an object that has some weight and a smooth flat surface on the bottom (eg. a small box

full of sand or something similar) near the top edge of the book.

Test 2• Cover the book-face with plastic film.• Half fill the box with sand or similar material.• Lift the edge of the book until the box begins to slide down.• Measure the height of the edge above the tabletop.• Now fill the box with sand and repeat the test

The greater the weight the greater the friction, therefore the resistance to movement will also beincreased. This is due to the increase in the load (weight) that results from the pull of gravity.

HEIGHT OFBOOK EDGE

FLAT SURFACE

TABLE TOP


Section 4: ASSESSMENT

THE CLASSROOM CONTEXT

This is an activity that would be suitable for individual students or small groups.

InvestigatingThe topics could be shared by group members and the report a combined individual and group task.The group is responsible for allocating topics.

DesigningThe lever tests require no special equipment so individual students could undertake the test proce-dures at home, provided they were given simple and comprehensive instructions. If it was a groupproject each member could develop one design option, and the final presentation would be a grouptask. The work of each member should be included in a group design folio.

ProducingIf it was a group activity individuals could be allocated specific tasks, such as: recording changesmade to the design as a result of experience in building the structure; ensuring material and tools areready for use; providing a spokesperson who negotiates with the teacher.

EvaluatingThis could be a group activity with every student contributing to the final presentation.

LINKING THE STUDENT ACTIVITIES IN EACH PHASE TO THE LEARNING OUTCOME.If you heeded the warning at the start of this section you would have discovered that there has to be alink between what students do and the learning outcome. The following diagrams show how all thisis done. It’s not done with mirrors but with arrows. The activities are linked to the curriculum focus.Remember what that was? If not immediately read the introduction to the Technology component ofthe CSF. The curriculum focus of course is linked to the learning outcome. By the clever use of thelittle arrows the diagram illustrates the link between activities and outcome. Why go to all thistrouble you ask? Well, the work the students do should provide information that will help you makethose on-balance judgements you read about in the assessment bit of the introduction.


Individual members of the group investigate different topics, such as the ones be-low.• Investigate the people who design and build machines. Who are these people?

What type of machines do they design and build?• Make a list of machines that have been designed to help people with disabilities,

and explain how these machines have assisted the user to lead a better life.Artificial limbs and wheel-chairs are examples of simple machines.

• Select a machine and begin exploring how using it will have an impact on theenvironment in the local community. The impact could be negative (pollutionor waste energy) or positive (reduce or eliminate pollution, or conserve energy).Pollution takes many forms: air, water, soil, noise, visual, etc.

• Conduct tests to discover the effect of changing processes on the output. Considerthe lever to be a process that converts the input into the output. The testingprocedure described in Section 3 can be used on a variety of levers and situations(section 1).

• A number of machines that we use today have electric motors to provide thepower to make them work. In earlier years some of these machines were operatedby human power; people pushed, pulled, turned and twisted levers and handlesto make them work. Make a list of these machines and describe how peopleoperated them before electric motors were used. The addition of the electricmotor means that there are two systems. One is the electric motor to convert theelectrical energy into kinetic energy, and the other the mechanism to give usthe desired output, such as rotating beaters on a food mixer or the backwardsand forwards motion of an electric knife. ð

LEVEL 4 SYSTEMS STRAND - INVESTIGATING PHASE

To achieve this level a student will haveto be able to:• investigate how systems have been

developed and applied to meethuman needs

• begin exploring the implications ofparticular systems on theenvironment in the local community

• explain what effect changingprocesses have on outputs

• consider how systems need to becombined to solve specific problems

Curriculum focus (ref. CSF)

ðð

ð

Create design options for constructingsystems for specific purposes and deviseways of monitoring and testing perform-ance.

Learning outcome

Activities in this phase


LEVEL 4 SYSTEMS STRAND - DESIGNING PHASE

During this phase the students should have the opportunity to demonstrate thefollowing:• Present at least two design options that explore the use of alternative

combinations of levers and linkages.• Select one of the design options as the preferred choice and give reasons to

support that choice.• Develop appropriate ways to test the performance of their solution.• Even though this is a cardboard model or prototype, the design could examine

the use of a battery-powered mechanism.Suggest suitable materials for the real product and give reasons for the selection.

To achieve this level a student will haveto be able to:• generate design proposals that

explore the use of alternative processcomponents

• suggest reasons for the choice of onedesign

• select from a range of energy sources• devise ways to test the performance

of their system


ð

Create design options for constructingsystems for specific purposes and deviseways of monitoring and testing perform-ance.

Learning outcome


ððð


LEVEL 4 SYSTEMS STRAND - PRODUCING PHASE

In this phase students should have the opportunity to demonstrate the following:• Use a range of tools, equipment (such as cutting knives, hole punch, ruler and

stapler) and materials safely and correctly.• Construct their systems to achieve design requirements as outlined in the design

brief.• Modify construction techniques where necessary to improve quality and

presentation. This includes the ability to make changes during the actualconstruction if problems are experienced.

• Maintain the equipment they use. This includes recognising faults and correctstorage procedures.

To achieve this level a student will haveto be able to:• use a range of purpose-designed-

tools, equipment and materials tosafely and correctly

• construct their systems to achievedesign requirements

• modify techniques to improve qualityand presentation maintain theequipment they use


ð

Organise and control systems to designspecifications, adopt safe work practices,and maintain tools and equipment.

Learning outcome


ððð


LEVEL 4 SYSTEMS STRAND - EVALUATING PHASE

To achieve this level a student will have to be able to cover the following:• Evaluate the performance of their systems against the design requirements set

out in the design brief, and use testing methods they have devised in the designphase.

• Comment on their success in efficiently using time, materials and other resources.Efficiency is a measure of success in reducing waste to a minimum.

• Present reports taking into account some environmental implications, such asusing materials that can be recycled or reducing the amount of energy neededto operate the device.

• Present reports in oral, written and graphic form.

To achieve this level a student will haveto be able to:• evaluate the performance of their

systems against the designrequirements using testing methodsthey have devised

• note their success in minimisingtime, waste and resources

• present reports taking into accountsome environmental implicationspresent reports in oral, written andgraphic form


ð

Assess and report on the performanceof the system taking into account someenvironmental considerations

Learning outcome


ððð


Section 5: FURTHER OPTIONS

5A: INTEGRATING LEARNING AREAS

Integration is the way to go so we are told, therefore this unit is designed to be integration friendly.Try a concept map and you will find all sorts of connections.

5B: ALTERNATIVE DESIGN BRIEFS

The information in this unit is generic; it belongs to a whole class of things called levers. It could beused if the task involved the design and construction of things that included levers. The knowledge ofenergy, force, work and power applies to any mechanical unit of work, and the technical informationabout levers becomes a very useful reference for solving many other problems.To demonstrate the versatility of this unit on the next page are a couple of other design briefs thatwould use the information in this unit.

Manufacturing

LEVERS ANDMACHINES

History

MaterialsSteam engines

New & old

Manufactured

Clocks

Horse & coach

ToolsHome

Appliances

People

OperatorsInventors

Machines

Engineers

Transport

Agriculture

Energy

EnvironmentForce

PowerWork

Fossil fuels PollutionFriction

Natural

Conservation

Sources

Forms


DESIGN BRIEF 1For centuries puppets have amused people of all ages. The bright colours and moving parts makethem interesting, and in more recent times Sesame Street has used puppets to entertain and educateyoung children.Recently a lot of school children have been caught not wearing their safety helmets when riding theirbicycles and all the schools in the area have decided to run a program that will educate students aboutthe dangers of not wearing a helmet. Each school has been asked to think of a mascot that would beused as the logo for the program.

Your taskYou are to design and make a puppet that could be used as the logo for the bicycle helmet program.

Things to think aboutThe solution must:

• be brightly coloured;• have at least two moving parts that are operated by pulling or pushing ;• be easily recognised by students; and• be no bigger than 300 x 300 millimetres.

Other instructions• You will work in groups of XXXX.• You have XXX weeks to complete the activity.• You may use cardboard as the main material.• Other materials such as paper, icypole sticks, sticky tape and string may be used.• Suitable cutting and joining techniques should be sued.• Your puppet must work when it is tested during your evaluation.

DESIGN BRIEF 2Litter is becoming a problem. You can see it in school playgrounds,shopping centres, parks and beaches. As part of the Keep Aus-tralia Beautiful campaign schools have been asked to submit ideason designing better bins to reduce the amount of litter that is dumpedon the ground rather than in rubbish bins. The receptacle must bebrightly coloured and blend in with the environment. Some rub-bish bins are easily overturned spilling the contents, and other binshave no cover and rubbish may be blown onto the ground.

Design taskYou have been asked to design and make a working model of a mechanism that will open and close alid or cover on the rubbish container.

Things to think about· The contents of a receptacle must be easily collected and taken to a central place for disposal.· People need to be able to dispose of the rubbish without touching the receptacle with their

hands.· The material used will have to be suitable for use inside and outdoors.· The receptacle should encourage people to use it.

Other instructionsYou may use whatever materials are available.The task is to be completed in XXXX weeks.


5C: WORKING WITH STUDENTS OF DIFFERING ABILITIES

The following diagrams show the differences between Levels 3, 4 and 5 in each phase. While the onedesign brief may be used for the whole class the activities students undertake in each phase may haveto be modified.Teachers are very resourceful people and catering for different levels is something you have donesuccessfully for many years. Always keep in mind the old saying, ‘The more things change the morethey stay the same.’ One wise old teacher once said, ‘If you stand still long enough one day you willbe in the vanguard of a major educational movement.’


Level 3

To achieve this level a student will have to be able to:• investigate everyday systems, recognising the roles of

people in their development and operation• explain the inputs, processes and outputs of simple

systems• investigate how various energy sources can be used to

make a system work• begin predicting and exploring the effect on the output

of changing the process while maintaining the sameinputs

Level 4

To achieve this level a student will have to be able to:• investigate how systems have been developed and

applied to meet human needs• begin exploring the implications of particular systems

on the environment in the local community• explain what effect changing processes have on outputs• consider how systems need to be combined to solve

specific problems

Level 5

To achieve this level a student will have to be able to:• investigate the role of technological systems within

households, communities and environments• consider how systems are applied• recognise the interrelationship between inputs, processes

and outputs• examine the use of a variety of energy sources• examine the roles of people as creators, controllers

and users of systems

Level 3

To achieve this level a student will have to be able to:• produce plans, drawings and models that illustrate

the basic parts and processes of their proposed systems• choose from a variety of energy sources (springs, water,

batteries, mechanical)• consider techniques, materials and equipment needed

for their tasks• suggest what effects altering the process would have

on the outputs

Level 4

To achieve this level a student will have to be able to:• generate design proposals that explore the use of

alternative process components• suggest reasons for the choice of one design• select from a range of energy sources• devise ways to test the performance of their system

Level 5

To achieve this level a student will have to be able to:• examine options when developing designs and justify

their decisions• consider social and aesthetic issues as well as

functional ones• produce diagrams, drawings and models using suitable

technical terms and symbols• devise performance criteria to better evaluate their

products

ð

SYSTEMS STRAND - INVESTIGATING PHASE

ð

SYSTEMS STRAND - DESIGNING PHASE

ðð


Level 3

To achieve this level a student will have to be able to:• work to his or her own plans• use appropriate equipment in a safe manner• construct his or her systems from every day and/or

commercial materials• modify and incorporate new ideas to deal with

difficulties• experiment with varying the process and look for

changes in the output

Level 3

To achieve this level a student will have to be able to:• use a range of purpose-designed- tools, equipment and

materials safely and correctly• construct their systems to achieve design requirements• modify techniques to improve quality and presentation• maintain the equipment they use

Level 5

To achieve this level a student will have to be able to:• use a range of specialist techniques to safely construct

and operate systems• understand how particular systems can be controlled

and managed by varying the inputs• modify the outputs with increasing skill• identify some faults in tools and equipment• work in a safe and responsible manner

Level 3

To achieve this level a student will have to be able to:• compare their product with their original plans• report the results of the functioning of the system and

how well it serves the purposes for which it wasintended

• describe the effects of varying the process• outline any modifications they may have made during

construction

Level 3

To achieve this level a student will have to be able to:• evaluate the performance of their systems against the

design requirements using testing methods they havedevised

• note their success in minimising time, waste andresources

• present reports taking into account someenvironmental implications

• present reports in oral, written and graphic form

Level 5

To achieve this level a student will have to be able to:• evaluate the system against the performance criteria

they have devised• record any modification and comment on the

suitability of their systems in a final report, based ontheir findings and comparisons with similar products

• suggest alterations that could be made to improve thesystem product

ð

SYSTEMS STRAND - PRODUCING PHASE

ð

SYSTEMS STRAND - EVALUATING PHASE

ðð


Section 6: SOME USEFUL INFORMATION

a and b: Student worksheets for use with the investigation of mechanical engi-neers.The pages for section 2 could be photocopied and given to students as a primary reference. However,they should be encouraged to use other sources such as dictionaries, encyclopedias, and relatives andfriends. If you have access to a multi-media computer you might like to explore the Internet and findother useful bits of information that your students could use. It is also very useful to be able to say atmorning tea, ‘I found this very interesting article on the Internet last night.’

c: A letter to be sent home.If you want to get the students to do some work at home you might like to think about sending homea letter explaining what this unit is all about. Not only does it keep parents and caregivers informed,it might also encourage those at home to help in some way.

d: Possible solutions for the design brief in Section 1.

e: Some possible mathematics associated with this unit.

f: Introducing the unit of work.Suggestions for introducing the unit of work to the class.


6A: QUESTION SHEET � PAUL

Paul is an engineer. He went to university and completed a degree course before he started workingas an engineer?

1. What was the name of the degree he had to complete, and what was the name of the university?

2. Use a dictionary to find the meaning of the words mechanical and engineer.

3. When he was at school Paul did a lot of tinkering at home. What does tinkering mean?

4. Mechanical engineers design machines. Give five examples of machines you would find aroundyour home, and another five that you might see if you went on a sightseeing trip.

5. What sort of work did Paul do when he first started as a mechanical engineer?

6. There was one project that he remembers well. What was it?

7. Why would mathematics and science be important to a mechanical engineer?

8. What sort of work is he doing now?

9. There are people like Paul who call themselves consulting engineers. What does this mean?

10.Paul likes being an engineer. Write down four things he likes about his work.


6B: QUESTION SHEET � BARBARA

Barbara is an engineer. She went to university and completed a degree course before she startedworking as an engineer.

1. What was the name of the degree she had to complete, and what was the name of the university?

2. Use a dictionary to find the meaning of the words mechanical and engineer.

3. When she was at secondary school Barbara liked two subjects. What were they?

4. Mechanical engineers design machines. Give five examples of machines you would find aroundyour home, and another five that you might see if you went on a sightseeing trip.

5. What sort of work did Barbara do when she first started as a mechanical engineer?

6. Pneumatic machines use compressed air to make them work. Describe one pneumatic machinethat you might see if you travel around or go shopping?

7. Barbara still remembers the biggest project at her first job. What was it?

8. Barbara’s knowledge of mathematics was very useful on one project. What was that project?

9. What sort of work is she doing now?

10.Would you say that her work on the oilrig could be exciting? What would make it exciting?

11.Barbara says that more girls should think about becoming engineers. Why do you think there is ashortage of women engineers?

12.Barabara likes being an engineer. Write down the reasons she gives for liking her work.


6C: LETTER FOR THE STUDENTS� PARENTS

Dear Parent,

Your child has been asked to do some work at home for the new learning area of Technology. You willhear words like machines, levers and systems and see cardboard models being tested. This is all partof their study of some of the simple machines that we use every day.

The purpose of this work is to introduce your child to the world of machines, and levers play a veryimportant part in even the largest and most complex machines. The work they have been asked to doat home is to investigate the use of different machines around the home, and to test a number ofdifferent levers and observe how they work. You can help them with this work.

• If you know something about machines and levers then get in and work with them.• If you know nothing about machines and levers join in and learn yourself.

If you have any questions or comments please contact me at school.

The teacher


6D: POSSIBLE SOLUTIONS TO THE DESIGN BRIEF IN SECTION 1

Some possible solutions to the problem posed in the design brief in section 1. Refer to section 1 aboutdrawing levers and linkages.

→→→→→ →→→→→

→→→→→ →→→→→→→→→→ →→→→→

→→→→→

Tongs Pliers

4 Bar Linkages Levers andLinkages


6E: SOME POSSIBLE MATHEMATICS ASSOCIATED WITH THIS UNIT.

Example 1 (Refer to Test “comparing the size of the effort and load’ in section 3)

The mathematical formula associated with this test is:

Force at the effort x distance from the fulcrum = Force at the load x distance from the effort

Students could calculate the possible result by using:• The number of marbles as the size of the effort and load• The distance from the fulcrum to the centre of the cup measured in centimetres

For example, if the effort (cup A) has 5 marbles and is 20 centimetres from the fulcrum the studentscould predict how far from the fulcrum will the load (cup B) have to be if it has ten marbles in it. Themathematics goes something like this.

5 x 20 = 10 x distance from the fulcrum

100 = 10 x distance from the fulcrum

Therefore what does 10 have to be multiplied by to get 100?Carry out the test to support the mathematics. Of course the results of the test may vary slightlybecause of errors in the testing. For example the distance may be closer to 9 or 11 centimetres.The same approach can be used to calculate the size of the effort needed to move a particular load.For example, if the load is 20 marbles and it is 5 centimetres from the fulcrum, what size effort isrequired if it is 20 centimetres from the fulcrum.

Force at the effort x distance from the fulcrum = Force at the load x distance from the effort

Force at the effort x 20 = 20 x 5

Force at the effort x 20 = 100

What do you have to multiply 20 by to get 100? Or, to put it another way, you divide 100 by 20.

CUP B

CUP A

MARKS

DISTANCE

→

→


6F: INTRODUCING THE UNIT

One possibility is to involve the class in a discussion about the problems people with a disabilitymight face doing tasks that we do every day; for example people in wheel chairs and those who sufferfrom arthritis and find it difficult to move or bend down. A list could be made on the chalkboard of:• tasks that people do every day including small ones such as opening doors, switching on lights,getting things out of cupboards, and picking things up from the floor; and• some suggestions for reducing the difficulty faced by these people; for example, door handles atthe right height and of the right shape, switches placed in convenient places, and sliding doors oncupboards and shelves at the right height.• ways we use now to help these people; for example, ramps, wide doors, grab rails on walls, and soon.

You might like to role-play a situation where a person with a disability is faced with problems doingsome every day task.• People with arthritis in their hand so the can’t close it, and turning a tap on and off• Someone with partial sight and finding the slot for money in a drink machine.• A person in a wheel chair who has dropped their glasses.

Documents

TWISTING, TURNING, TILTING AND OTHER GROOVY …rapidproto/outreach/mech.pdfTwisting Turning Tilting and Other Groovy Movements – 1 TWISTING, TURNING, TILTING AND OTHER GROOVY MOVEMENTS