1. Lesson 2: Simple Machines
Chapter 12
Lesson 2: Simple Machines

2. Types of Simple Machines
A simple machine is a machine that does work with only one movement of the machine.
There are six types of simple machines: lever, pulley, wheel and axle, inclined plane, screw and wedge.

3. Lever
Lever
a bar that is free to pivot about a fixed point, or fulcrum
“Give me a place to stand and I will move the Earth.”
– Archimedes
Engraving from Mechanics Magazine, London, 1824
Effort arm
Resistance
arm
Fulcrum

4. Lever First Class Lever can increase force, distance, or neither
changes direction of force

5. Lever
Second Class Lever
always increases force

6. Lever
Third Class Levers
always increases distance

7. Pulley
Pulley
grooved wheel with a rope or chain running along the groove
a “flexible first-class lever” F F E L

8. Wheel and Axle Wheel and Axle
two wheels of different sizes that rotate together
a pair of “rotating levers”
Wheel
Axle

9. Wheel and Axle
input force is applied to the wheel, output force exerted by the axle.
Ex: Doorknobs, screwdrivers, faucet handles

10. Inclined Plane Inclined Plane Slanted surface used to raise objects h

11. Screw
Screw
inclined plane wrapped in a spiral around a cylinder

12. Wedge
Wedge
a moving inclined plane with 1 or 2 sloping sides

13. Wedge Zipper 2 lower wedges push teeth together
1 upper wedge pushes teeth apart

14. Ideal Mechanical Advantage (IMA) frictionless machine
MA greater than 1 increases force
MA = output force = input distance
input force output distance