Simple Machines

Machine – a tool that helps us do work with less force

Machines help us by:1. Changing the amount of force on an

object.

2. Changing the direction of the force.

Six basic simple machines:

• Lever

• Inclined Plane

• Wedge

• Screw

• Wheel and Axle

• Pulley

LEVER A bar that pivots on top of a fixed point called a fulcrum. It is used

to lift or move a load.A lever operates on the principle that a force applied at

one point lifts a resistive weight at a second point by rotating it about the fulcrum.

There are three classes or types of levers.

Lever examples: a seesaw, crowbar, baseball bat, rake, hammer, shovel, tweezers

Three Classes of Levers

An example of a first class lever is a seesaw.

An example of a second class lever is a wheelbarrow.

An example of a third class lever is a fishing pole.

Lever Video

INCLINED PLANEA slanted flat surface with one

end raised higher than the other. An inclined plane makes it easier to slide a load up or down rather

than having to directly lift it.There are no moving parts in an inclined plane.

Examples: ramp, stairs, slide, roof, escalator, gangplank,

driveway

Inclined Plane Video

WEDGE Two inclined planes put together.

A wedge is used to raise an object or split an object.

Examples: knife, doorstop, ax, needle, pin, nail, saw

Wedge Video

SCREWAn inclined plane wrapped

around a pole or cylinder. A screw is used to hold materials

together.

Examples: drill bit, screws, spiral staircase, corkscrew, meat grinder

Screw Video

WHEEL AND AXLEA wheel with a rod called an axle through the center. The wheel turns on the axle to help lift or

move a load quickly and easily.Examples: steering wheel,

doorknob, screwdriver, tractor wheel, car, pencil sharpener, bike

Wheel and Axle Video

PULLEY A wheel with a rope or chain

wound around it. A pulley can move a load up or down or

change the direction of a force.Examples : flagpole, clothesline, cranes, fishing reel, sailboat mast

Pulley Video

Scenario 1

• I have a bucket of paint I need to get to the painters on the third floor of a building. What simple machine would be best for the job and why?

Scenario 2

• I need to chop a piece of wood, so it will fit in my fireplace. What simple machine would be best for the job and why?

Scenario 3

• My grandmother is in a wheelchair and needs to get on stage for a performance. What simple machine would be best for the job and why?