1. Chapter 14 Section 3

2. Simple Machines There are 6 basic types of simple machines.
The inclined plane
The wedge
The screw
The lever
The wheel and axle
The pulley

3. Inclined Plane Inclined plane is a flat, sloped surface.
It allows you to exert your input force over a longer distance.
Mechanical Advantage = Length of incline
Height of incline

4. Wedge
A wedge is a device that is thick at one end and tapers to a thin edge at the other end.
When you use a wedge, instead of moving an object along the inclined plane, you move the inclined plane itself.
Mechanical Advantage=Length of wedge
width of wedge

5. Screws
A screw can be thought of as an inclined plane wrapped around a cylinder.
The threads of a screw act like an inclined plane to increase the distance over which you exert the input force.
The closer together the threads of a screw are, the greater the mechanical advantage.
Think of the length around the threads as the length of the inclined plane.

6. Levers
A lever is a rigid bar that is free to pivot, or rotate, on a fixed point (fulcrum).
1. Think about opening a paint can. Pg. 426.
2. Mechanical Advantage = Distance from fulcrum to input force ÷ distance from fulcrum to output force.

7. Classes of Levers
First-Class Levers – always change the direction of the input force. Ex. Scissors, pliers, seesaws.

8. Second-Class Levers – increase force, but do not change direction of the input force. Ex. Doors, nutcrackers, bottle openers.

9. Third-Class Levers – increase distance, but do not change the direction of the input force. Ex. Fishing poles, shovels, baseball bats

10. Wheel and Axle
A wheel and axle is made of two circular or cylindrical objects fastened together that rotate about a common axis.
The larger radius is the wheel
The smaller radius is the axle
Ex. Screwdriver, doorknob, steering wheel.

11. Wheel and Axle How It Works pg. 428
Mechanical Advantage = Radius of wheel
Radius of axle

12. Pulley
A pulley is made of a grooved wheel with a rope or cable wrapped around it.
1. decreases the amount of input force needed and changes direction of input force. Ex. flagpoles

13. Types of Pulleys
Fixed Pulley – does not change amount of force. Only changes the direction of force.

14. Movable Pulley – increases output force. Does not change direction.

15. Block and Tackle – made up of both a fixed and moveable pulley.
SEE PAGE 431

16. Compound Machines
A machine that utilizes two or more simple machines.