1. Lever A lever is a bar that is free to turn, about a fixed point.

2. Fulcrum The fixed point of a lever is called the fulcrum.

3. Effort arm The part of the lever on which the effort force is applied is called the effort arm.

4. Resistance Arm The part of the lever that exerts the resistance force is called the resistance arm.

5. Mechanical Advantage (MA) Length of the effort arm is the distance from the fulcrum to the point where effort force is applied. Length of the resistance arm is the distance from the fulcrum to the point where effort force is applied.

6. MA MA=Length of effort arm/length of resistance arm

7. Different type or classes of levers First class Second class Third class

8. A pulley Is a grooved wheel with a rope or a chain running along the groove.

9. Fixed pulley Is attached to something that doesn’t move,such as ceiling, wall, or tree.

10. A moveable pulley Is attached to the object being moved. Unlike the fixed pulley, a moveable pulley does multiply the effort force. And it has greater MA.

11. A wheel and axel Is a simple machine consisting of two wheels of different sizes that rotate together.