### Unit 7: Momentum and Collisions

We use the term momentum in various ways in everyday language. We speak of sports teams gaining and maintaining the momentum to win. Generally, momentum implies a tendency to continue on course - to move in the same direction - and is associated with mass and velocity. Momentum has its most important application in analyzing collision problems, and, like energy, is important because it is conserved. Only a few physical quantities are conserved in nature, and studying them yields fundamental insight into how nature works, as we shall see in our study of momentum.

**Completing this unit should take you approximately 12 hours.**

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

- define linear momentum;
- use Newton's 2nd law in terms of momentum;
- describe the relationship between impulse and momentum;
- define elastic, inelastic, and totally inelastic collisions;
- use conservation of momentum to solve collision problems; and
- demonstrate the physics behind rocket propulsion.

### 7.1: Momentum and Impulse

Read sections 8.1, and 8.2 of "Chapter 8: Linear Momentum and Collisions". 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 SAC125. The solutions are available, but make a serious attempt to solve the problems before looking at the solutions.

### 7.2: Conservation of Momentum in Collisions

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

Read sections 8.3, 8.4, and 8.5 of "Chapter 8: Linear Momentum and Collisions". Look over the conceptual questions in each section to test your understanding.

Try solving these practice problems.

Work on solving problems 1 through 5 from SAC104. The solutions are available, but make a serious attempt to solve the problems before looking at the solutions.

### 7.3: Collisions in Two Dimensions

Read sections 8.6, and 8.7 of "Chapter 8: Linear Momentum and Collisions". Look over the conceptual questions in each section to test your understanding.

Try solving these practice problems.

### Unit 7 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