Simple MachinesSimple MachinesPresentation by:Presentation by:

Linda HortonLinda Horton

Competency Goal 4: The learner will build an understanding of technological designs.

Objective-Objective-4.4 Evaluate the attributes of simple machines that can be manipulated or combined to affect outcomes.

Essential Questions:Essential Questions:

What are the attributes of simple What are the attributes of simple machines? machines?

How can the attributes of machines How can the attributes of machines be manipulated or combined to be manipulated or combined to affect outcomes?affect outcomes?

Can a single Can a single person lift a person lift a car?car?

A car can be lifted by a single person!

A car jack can be used by one person to lift a car. By using a lever, the jack pushes upward with much more force than a person uses to turn the crank.

What do machines do?What do machines do? A machine consists of fixed and moving parts A machine consists of fixed and moving parts

that modifies mechanical energy and transmits that modifies mechanical energy and transmits it in a more useful form. it in a more useful form.

A simple device, such as a lever, a pulley, or A simple device, such as a lever, a pulley, or an inclined plane, that alters the magnitude or an inclined plane, that alters the magnitude or direction, or both, of an applied force; a simple direction, or both, of an applied force; a simple machine. machine.

A system or device for doing work, as an A system or device for doing work, as an automobile or a jackhammer, together with its automobile or a jackhammer, together with its power source and auxiliary equipment power source and auxiliary equipment

Simple MachinesSimple Machines A simple device, such as a A simple device, such as a

lever, pulley, inclined plane, lever, pulley, inclined plane, wedge, screw, wheel and wedge, screw, wheel and axle ; a machine without axle ; a machine without moving parts.moving parts.

A simple machine reduces the A simple machine reduces the amount of effort needed to amount of effort needed to move something, move something,

Harcourt Science Book Harcourt Science Book Unit F Chapter 2Unit F Chapter 2

Lesson 1Lesson 1How Does a Lever Work?How Does a Lever Work?

What is a lever?What is a lever? Lever:Lever:            

A straight rod or board that pivots A straight rod or board that pivots on a point known as a fulcrum. The on a point known as a fulcrum. The fulcrum can be moved depending fulcrum can be moved depending on the weight of the object to be on the weight of the object to be lifted or the force you wish to exert. lifted or the force you wish to exert. Pushing down on one end of a Pushing down on one end of a lever results in the upward motion lever results in the upward motion of the opposite end of the fulcrum.of the opposite end of the fulcrum.Examples:Examples: Door on Hinges, Door on Hinges, Seesaw, Hammer, Bottle OpenerSeesaw, Hammer, Bottle Opener

Parts of LeverParts of LeverA lever is made up of a bar that turns around a fixed point. The fixed point, or one that doesn’t move, is called a fulcrum.

How do Levers Work?How do Levers Work? When you push or pull a When you push or pull a

lever, you put a force, lever, you put a force, called the called the effort forceeffort force, on , on one part of the bar. This one part of the bar. This force causes the lever to force causes the lever to turn around the turn around the fulcrumfulcrum. . The other end of the lever The other end of the lever moves. The resulting moves. The resulting force on that end is what force on that end is what you use to move a load, you use to move a load, or do work. or do work.

Different Types of LeversDifferent Types of LeversWhat supplies the effort force on the opener?

What is used as the fulcrum on a wheel barrow?

Where is the resulting force of the broom?

Your hand.

The bristles of the broom.

A wheel.

What Are The Parts of a Lever?What Are The Parts of a Lever?

A bar that turns around a point called a fulcrum.

Levers and ForcesLevers and ForcesWhat do all the levers have in common?

What happens when the forces applied to a seesaw type lever and the distance of the forces form the fulcrum are equal?

How can a small effort force be made to balance a large weight on some levers?

All the levers have a bar that turns on a fulcrum, and all can change the size of the force applied to them.

The lever balances.

By moving the fulcrum closer to the weight.

How does a lever change the force How does a lever change the force applied to it?applied to it?

It changes the direction or size of the force.It changes the direction or size of the force.

Levers in ToolsLevers in ToolsMany hand tools are levers. Many hand tools are levers.

Name three tools that are levers.Name three tools that are levers.

ScissorsPliersCrow bar

Garden shearsNail ClippersBottle Opener

HingesHammer

Did you remember three? Let’s see if you did!

WorkWorkWorkWork is done on an object when a force moves the object through a distance. is done on an object when a force moves the object through a distance.

The force and motion must be in the same direction. The force and motion must be in the same direction. To find the work done on an object multiply the force used to move the To find the work done on an object multiply the force used to move the object by the distance the object moves.object by the distance the object moves.

force x distance = force x distance = WorkWork

Example: If you had to lift a 10-newton rock 2 meters.Example: If you had to lift a 10-newton rock 2 meters.10-newton rock X 2 meters = 20 (newton-meters)10-newton rock X 2 meters = 20 (newton-meters)

WorkWorkWorkWork is done on an object when a force moves the object through a distance. is done on an object when a force moves the object through a distance. The force and motion must be in the same direction. The force and motion must be in the same direction.

To find the work done on an object multiply the force used to move To find the work done on an object multiply the force used to move the object by the distance the object moves.the object by the distance the object moves.

force x distance = force x distance = WorkWork

SummarySummary The basic machines The basic machines

that make up all other that make up all other machines are simple machines are simple machines. A lever is a machines. A lever is a simple machine that simple machine that changes the direction changes the direction or size of a force. or size of a force. Work is done on an Work is done on an object through a object through a distance. distance.

ReviewReview

What are the parts of a lever?What are the parts of a lever?

A bar and a fulcrum, a point around which the bar moves.

ReviewReview

How does a pry bar help you How does a pry bar help you do work?do work?

When you apply a force over a certain distance in one direction to the long end of the pry bar, the pry bar exerts a greater force in the opposite direction over a shorter distance.

ReviewReviewWhat tools are levers? Name at least What tools are levers? Name at least

three.three.

Hammers, hinges, pliers, scissors, garden shears, bottle opener, pry bar, nail clippers

ReviewReview

What is work?What is work?

When a force moves an object over a distance.

ReviewReview

Why do you think it is Why do you think it is important that the bar of a important that the bar of a lever not bend?lever not bend?

If the bar bent, it would not be able to transfer the force from the effort to the load.

ReviewReview

An example of a lever is aAn example of a lever is aa) wrencha) wrenchb) screwb) screwc) seesawc) seesawd) rockd) rock

C seesaw

Identify the locations of the fulcrum, effort force, and resulting force.

The bat is an extension of the batter’s hands. The fulcrum is the batter’s wrists.

The resulting force is from the large end of the bat.

The effort force is applied by the batters hands. The effort force is between the fulcrum and the resulting force .

Fun websites to help you learn moreFun websites to help you learn more

http://teacher.scholastic.com/dirtrep/simple/index.htmhttp://teacher.scholastic.com/dirtrep/simple/index.htm

http://edheads.org/activities/simple-machines/index.htmhttp://edheads.org/activities/simple-machines/index.htm

End of lesson 1End of lesson 1 Information and pictures from Harcourt Science Information and pictures from Harcourt Science

Units E and F Teacher’s EditionUnits E and F Teacher’s Edition