Simple and Compound Machines

Simple Machines- the ability to do work

Compound Machines- machine made up of two or more simple machines that work

together to do work

There are 6 simple machines:

• Inclined Plane- ramp or slanting surface that connects a lower level to a higher level

• Lever - stiff bar that rest on a support called a fulcrum

• Pulley- grooved wheel with a rope or cable around it

• Screw- an inclined plane wrapped around a pole

• Wedge- slanting side ending in a sharp point used to split, lift, or hold

• Wheel and Axle- circular device with a rod, called an axle, through its center

Inclined Plane- allows things to move up or down it

Lever- lifts or moves loads

Levers-First Class

• In a first class lever the fulcrum is in the middle and the load and effort is on either side

• Think of a see-saw

Levers-Second Class

• In a second class lever the fulcrum is at the end, with the load in the middle

• Think of a wheelbarrow

Levers-Third Class

• In a third class lever the fulcrum is again at the end, but the effort is in the middle

• Think of a pair of tweezers

Pulley- moves things up, down, or across

Screw- holds or lifts things together

Wedge- lifts, splits, and holds

11

Wedge• The wedge is a

modification of the inclined plane. Wedges are used as either separating or holding devices.

• A wedge can either be composed of one or two inclined planes. A double wedge can be thought of as two inclined planes joined together with their sloping surfaces outward.

Wheel & Axle- lifts or moves loads

Complex Machines- Find the Simple Machines Within

Compound Machines