### Unit 6: Work and Energy

Energy is the capacity of a physical system to perform work. It plays an essential role both in everyday events and in scientific phenomena. You can probably name many forms of energy from that provided by our foods to the energy we use to run our cars to the sunlight that warms us on the beach. Not only does energy have many interesting forms, but it is involved in almost all phenomena and is one of the most important concepts of physics.

Energy can change forms, but it cannot appear from nothing or disappear without a trace. Thus, energy is one of a handful of physical quantities that we say is conserved.

**Completing this unit should take you approximately 14 hours.**

Upon successful completion of this unit, the student will be able to:

- calculate the work done on an object by a force;
- use the relationship between work done and the change in kinetic energy to make calculations;
- state the work-energy theorem;
- describe the concept of potential energy and how it relates to work;
- compare and contrast conservative and non-conservative forces;
- solve dynamics problems using conservation of energy;
- illustrate what is meant by power; and
- compare and contrast renewable and non-renewable energy sources.

### 6.1: Work and Kinetic Energy

Watch this lecture series, pausing to take notes, before moving on to the reading below.

Read sections 7.1 and 7.2 of "Chapter 7: Work, Energy, and Energy Resources".

Try solving these practice problems.

In this animation, you will vary the angle between the two vectors and observe the effect on the dot product.

Work on solving problems 1, 2, and 3 from SAC122. The solutions are available, but make a serious attempt to solve the problems before looking at the solutions.

### 6.2: Conservative Forces and Potential Energy

Read sections 7.3 and 7.4 of "Chapter 7: Work, Energy, and Energy Resources". Look over the conceptual questions in each section to test your understanding.

Try solving these practice problems.

### 6.3: Conservation of Energy

Read sections 7.5 and 7.6 of "Chapter 7: Work, Energy, and Energy Resources". Look over the conceptual questions in each section to test your understanding.

Work on solving problems 4, 5, and 6 from SAC102. The solutions are available, but make a serious attempt to solve the problems before looking at the solutions.

### 6.4: Power

Read sections 7.7, 7.8, and 7.9 of "Chapter 7: Work, Energy, and Energy Resources". Look over the conceptual questions in each section to test your understanding.

Try solving these practice problems.

Work on solving problems 1 through 4 from SAC124. The solutions are available, but make a serious attempt to solve the problems before looking at the solutions.

### Unit 6 Assessment

Take this assessment to see how well you understood this unit.

- This assessment
**does not count towards your grade**. It is just for practice! - You will see the correct answers when you submit your answers. Use this to help you study for the final exam!
- You can take this assessment as many times as you want, whenever you want.

- This assessment