Chapter 9.2

Simple Machines

The 6 Simple Machines

• All machines are made up of some of the 6 simple machines. They are:

• Wheel and axle

• Pulley

• Lever

• Wedge

• Screw

• Inclined Plane

The 6 Simple Machines

Lever Pulley

Wheel and Axle

WedgeScrew

Inclined Plane

SIMPLE MACHINES

LEVER A lever is a simple

machine.  It is a board or bar that rests on a turning point.  This turning point is called the fulcrum.  An object that a lever moves is called the load.  The closer the object is to the fulcrum, the easier it is to move.  

Levers

• Let's examine the lever • Three parts:

– Fulcrum or pivot point– Loaded lever arm– Effort (push or pull)

lever arm

The Lever - can change the direction of the force- can multiply the force of the effort

Three types of levers based on the position of the fulcrum (or pivot point).

EXAMPLES OF LEVERS

• Bottle openers

• Crow bars

 

SIMPLE MACHINES

WHEEL AND AXLE

The wheel and axle is another simple machine.  The axle is a rod that goes through the wheel.  This lets the wheel turn.  It is easy to move things from place to place with wheels and axles. 

The Wheel and Axle

• Two or more wheels are connected by an axle.

• The wheel turns with or around the axle.

• This car wheel has a big axle that it rotates around when the car moves.

The wheel and axle- multiplies the effort distance or force

The captain uses a large wheel to applya greater force to a small axle which controls the steering of the ship.

This shows that a small axle (handle)attached to the grind stone, increasethe distance that the stone wheel moves.

EXAMPLES OF WHEEL AND AXLE

• Cars • Roller Skates • Wagons • Door Knobs • Gears in Watches,

Clocks, and Bicycles

SIMPLE MACHINES

INCLINED PLANEA simple machine that is a flat surface that is higher on one end.  You can use this machine to move an object to a lower or higher place.  Inclined planes make the work of moving things easier.  You would need less energy and force to move objects with an inclined plane. 

The Inclined Plane

• It is a slanted surface or ramp.

• It makes moving objects easier.

• Roads are also inclined planes. Instead of going straight up, like this: roads go up at small angles, like the picture.

SIMPLE MACHINES

WEDGE

A wedge is a simple machine used to push two objects apart.  A wedge is made up of two inclined planes.  These planes meet and form a sharp edge.  This edge can split things apart.  

The Wedge

• A wedge is used to split, tighten, or secure a hold.

• A wedge is usually a triangle shape with a sharp point.

• If you apply force at one end, the wedge will go between something, in this case an ax splits a piece of wood.

Where can we find wedges?

• Wedges that split:• Your teeth!• Every time you bite

into something, you are using a wedge.

• Wedges that cut:• A saw!• A knife!

• Wedges that tighten:• A doorstop to keep

the door open.• Wedges that hold

things together:• A nail holds wood to a

wall or other wood.

SIMPLE MACHINES

SCREW  A screw is a simple machine that is

made from another simple machine.  It is actually an inclined plane that winds around itself.  A screw has ridges and is not smooth like a nail.  Some screws are used to lower and raise things.  They are also used to hold objects together. 

EXAMPLES OF SCREWS

• Jar Lids • Light Bulbs • Stools • Clamps • Spiral stairs• Jacks (to lift car so

you can change the tire)

Archimedes Screw

• used in ancient times to bring water up from the river.

SIMPLE MACHINES

PULLEYThis simple machine is made up of a wheel and a rope.  The rope fits on the groove of the wheel.  One part of the rope is attached to the load.  When you pull on one side of the pulley, the wheel turns and the load will move.  Pulleys let you move loads up, down, or sideways.  Pulleys are good for moving objects to hard to reach places.  It also makes the work of moving heavy loads a lot easier.