1. Unit 5 - Work and Energy CHAPTER 8 CONCEPTUAL PHYSICS BOOK CHAPTER 6 PHYSICS BOOK

2. Part 1 WORK, ENERGY, AND POWER

3. A New Perspective on Motion  We have been analyzing motion through the perspective of Newton’s Laws dealing with acceleration, velocity, and displacement.  In this chapter, we will look at motion from a different perspective – that of work and energy.

4. What is Work?  When a force acts upon an object and causes its displacement, it is said that work has been done on the object.  The force MUST cause a displacement! No work is done if the object doesn’t move.

5. Is There Work? 1. A woman pushes a shopping cart across the floor.  YES – Force causing displacement. 2. A man pushes against a wall.  NO – No displacement 3. A book falls off a table to the ground.  YES – Gravity provides the force to cause displacement 4. A child holds a book over her head while she stands on a moving walkway.  NO – The force is not causing the displacement.

6. Calculating Work

8. Units for Work

9. Example #1

10. Example #2

11. Example #3

12. Example #4

13. Energy  Energy (E) – the ability to do work.  Types of energy:  Mechanical – kinetic energy + potential energy  Electrical  Nuclear  Heat  Chemical  Sound

14. Kinetic Energy

15. Kinetic Energy Example

16. Work-Energy Theorem

17. Work-Energy Theorem Example 1

18. Work-Energy Theorem Example 2

19. Gravitational Potential Energy

20. Potential Energy Example