Machines Made Simple

Chapter 14

Simple MachinesAncient people invented simple machines that

would help them overcome resistance forces and

allow them to do the work against those forces.

2

Simple Machines

• A simple machine is a machine that does work with only ONE movement

• Six basic types• Designed to make work easier,

faster, or to change the direction of the force

• Few or no moving parts• Combine to form more complex

machines (i.e. compound machines)

Compound Machines

• A machine made up of 2 or more simple machines is called a compound machine

• Examples: scissors, pencil sharpener, car, microwave, oven

Inclined Plane

Inclined Plane

• An inclined plane is a flat, sloped surface

• Longer and less steep = smaller force needed

• Shorter and more steep = larger force needed

EXAMPLES: ramps, hillside roads, stairs

Wedge

Wedge

• A wedge is two inclined planes put together and has a cutting edge

• EXAMPLES: axes, door stops, your front teeth, scissors, knife blades

Screw

Screw• A screw is an inclined plane

wrapped around a cylinder or post (inclined plane forms screw threads).

• A screw holds things together

EXAMPLES: jar lid, screw, drill bit

Lever

Lever

• A lever is any rigid/stiff rod or plank that pivots, or rotates, about a pivot point (called the fulcrum).

• EXAMPLES: hammer, rake, nut cracker, tweezers, scissors, crow bar, broom

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Pulley

Pulley• A pulley consists of a

grooved wheel with a rope or cable wrapped over it.

• A pulley changes the direction of the applied force.

• EXAMPLES: used on flagpoles, used on sails on a boat, used in cranes

Wheel and Axle

Wheel and Axle• A wheel and axle consists of two

circular objects of different sizes that are attached in such a way that they rotate together.

• EXAMPLES: a fan, ferris wheel, doorknob, car wheel, screw driver

Simple Machines

Eduardo is helping his family move out of their

old house. Help him decide which task would be easier, and then help

him figure out what simple machine makes the job

easier.

Eduardo has to move some heavy boxes into the moving

truck.

A B

B would be easier because a ramp is an inclined plane.

Eduardo has to move a heavy box a long distance.

A B

A would be easier because the wagon has wheels and axels.

Eduardo needs to tear off a piece of packing tape.

A B

B would be easier because the edges of the scissors are wedges.

Eduardo needs to move a heavy box to his room on the fourth floor.

A B

B would be easier because Eduardo is using a pulley.

Eduardo needs to help his father move the refrigerator.

A would be easier because the dolly is a lever (with wheels and an axel).

A B

Eduardo needs to help his father change a flat tire on the moving truck.

A B

B would be easier because a jack uses a screw.

Now that Eduardo and his family have reached their

new house, they need some help in unpacking their

belongings. Help Eduardo decide on the best simple

machine to use in each situation.

Eduardo needs to open the boxes his mom sealed with packing tape.

What simple machine should he use?

Eduardo should use a wedge (probably a pair of scissors).

The door to the moving truck is jammed shut. What simple machine might Eduardo’s father use to open

it?

Eduardo’s father should use a lever (most likely a crowbar).

Eduardo needs to carry the boxes out of the moving truck. What simple machine will make this

easier?

Eduardo needs an inclined plane (a ramp) to carry the boxes out of the truck.

There is a flagpole outside Eduardo’s new school. What simple machine

could be used to raise and lower the flag?

A pulley is used to raise and lower the flag.

Eduardo’s mom wants to hang a cabinet in the new kitchen. What simple machine might she use to

attach it to the wall?

Eduardo’s mom could use a screw to attach the cabinet to the wall and hold it in place.

Eduardo helped his father install doorknobs in the new house.

What kind of simple machine is a doorknob?

A doorknob is a wheel and axel.

Simple Machines

Lever

Wheel and axel

Wedge

Screw Pulley

Inclined plane

Identifying Simple Machines

Inclined plane / Lever

Wheel and axel Wedge

Screw Pulley Inclined plane

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Image Sources

<http://etc.usf.edu/clipart><http://www.oz.net/~peragine/doorknob.jpg><http://www.theteachersguide.com/clipart/scissors.gif><http://www.weprintcolor.com/stockimages/construction/

images/Black%20metal%20crowbar.jpg><http://67.19.222.106/military/graphics/flagpole.jpg><http://www.morris.umn.edu/UMMimages/public/images/

campus_misc/flagpole.jpg><http://www.phillips-screw.com/images/homeMain.jpg><http://mws.mcallen.isd.tenet.edu/mchi/ipc/ch15htm/

images15/Screw.jpg><http://www.discountramps.com/handi-van_ramp.gif>http://staff.harrisonburg.k12.va.us/~mwampole/1-resources/

simple-machines/flag-pole.jpg

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Images Sources (cont.)

<http://www.physics.uwaterloo.ca/demo/bikewheelgyro.html>

<http://www.piratescave.co.uk/about_us.htm><http://staff.harrisonburg.k12.va.us/~mwampole/1-

resources/simple-machines/handicap-ramp.html><http://library.thinkquest.org/J002079F/

wedge.htm><http://www.idahoptv.org/dialogue4kids/season7/

simplemachines/facts.html><http://www.scienceclarified.com/Io-Ma/Machines-

Simple.html>