1. Chapter 8
Section 3 Types of Machines
Bellringer
What type of machine can be found on at least half the students in this room right now? What kinds of machines were common 50 years ago? 100 years ago? Are any of the same machines around today that were common in the 1800s? What has changed about those same machines today?

2. Chapter 8
Section 3 Types of Machines
Objectives
Identify and give examples of the six types of simple machines.
Analyze the mechanical advantage provided by each simple machine.
Identify the simple machines that make up a compound machine.

3. Chapter 8
Section 3 Types of Machines
Levers
A lever is a simple machine that has a bar that pivots at a fixed point, called a fulcrum.
First-Class Levers With a first-class lever, the fulcrum is between the input force and the load.

4. Chapter 8 Levers, continued
Section 3 Types of Machines
Levers, continued
Second-Class Levers The load of a second-class lever is between the fulcrum and the input force.

5. Chapter 8 Levers, continued
Section 3 Types of Machines
Levers, continued
Third-Class Levers The input force in a third-class lever is between the fulcrum and the load.

6. Chapter 8
Section 3 Types of Machines
Pulleys
A pulley is a simple machine that consists of a wheel over which a rope, chain, or wire passes.
Fixed Pulleys A fixed pulley is attached to something that does not move.

7. Chapter 8 Pulleys, continued
Section 3 Types of Machines
Pulleys, continued
Movable Pulleys Unlike fixed pulleys, movable pulleys are attached to the object being moved.
Blocks and Tackles When a fixed pulley and a movable pulley are used together, the pulley system is called a block and tackle.

8. Chapter 8
Section 3 Types of Machines
Pulleys, continued

9. Chapter 8
Section 3 Types of Machines
Wheel and Axle
What Is a Wheel and Axle? A wheel and axle is a simple machine consisting of two circular objects of different sizes.

10. Wheel and Axle, continued
Chapter 8
Section 3 Types of Machines
Wheel and Axle, continued
Mechanical Advantage of a Wheel and Axle The mechanical advantage of a wheel and axle can be found by dividing the radius (the distance from the center to the edge) of the wheel by the radius of the axle.

11. Chapter 8 Inclined Planes
Section 3 Types of Machines
Inclined Planes
An inclined plane is a simple machine that is a straight, slanted surface.
Mechanical Advantage of an Inclined Plane The mechanical advantage (MA) of an inclined plane can be calculated by dividing the length of the inclined plane by the height to which the load is lifted.

12. Chapter 8
Section 3 Types of Machines

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Section 3 Types of Machines
Inclined Planes, continued
Wedges A wedge is a pair of inclined planes that move.
Mechanical Advantage of Wedges can be found by dividing the length of the wedge by its greatest thickness.

14. Inclined Planes, continued
Chapter 8
Section 3 Types of Machines
Inclined Planes, continued
Screws A screw is an inclined plane that is wrapped in a spiral around a cylinder.
Mechanical Advantage of Screws The longer the spiral on a screw is and the closer together the threads are, the greater the screw’s mechanical advantage is.

15. Chapter 8 Compound Machines
Section 3 Types of Machines
Compound Machines
What Are Compound Machines? Compound machines are machines that are made of two or more simple machines.
Mechanical Efficiency of Compound Machines The mechanical efficiency of most compound machines is low, because compound machines have more moving parts than simple machines do. Thus, there is more friction to overcome.