1. Chapter 8
Work and Machines

2. Define and explain work Measure and calculate work
Objectives of chapter 8
Define and explain work
Measure and calculate work

3. Work
What happens when an object changes its position by moving in the direction of the force that is being applied

4. Measuring Work Work = Force x Distance Example
Work = 2 newtons x 10 meters
Work = 20 joules

5. Joule
The metric unit of work

6. Force, work and distance is always related
Force= work / distance Distance = work / force

7. Power
The amount of work a person does within a given period of time

8. Watt
The unit used to measure power.

9. Energy
The ability to do work

10. Kinetic Energy
Energy of motion

11. Potential Energy
Stored energy

12. Forms of Energy
Chemical- stored in bonds
Heat- moving particles
Mechanical- energy in moving objects
Nuclear- stored in the nucleus
Radiant- associated with light
Electrical- causes electrons to move

13. Generator
A device used to convert mechanical energy

14. Law of Conservation of Energy
Energy cannot be created or destroyed

15. Simple Machine
A tool with few parts that makes it easier or possible to do work

16. Lever
A simple machine containing a bar that can turn around a fixed point

17. Fulcrum
A fixed point around which a lever rotates

18. Effort Force, Fe
The force applied to a machine by the user

19. Resistance Force, Fr
The force applied to a machine by the object to be moved

20. Work Output
Work put into a machine by its user

21. Work Output
Work done by a machine against resistance

22. Efficiency
How well a machine performs

23. Mechanical advantage, MA
Factor by which a machine multiplies the effort of force

24. Effort arm
The distance between the fulcrum and the effort force of a lever.

25. Resistance arm
The distance between the fulcrum and resistance force of a lever.

26. Pulley
A simple machine made up of a rope, chain, or belt wrapped around a wheel.

27. Inclined Plane
A simple machine made up of a ramp, used to lift an object.

28. Screw
A simple machine made up of an inclined plane wrapped around a straight piece of metal.

29. Wedge
A simple machine made up of an inclined plane or pair of inclined planes that are moved.

30. Wheel and Axle
A simple machine made up of a wheel attached to a shaft.