### Unit 5: Circular Motion and Gravity

In this unit, we will study the simplest form of curved motion: uniform circular motion, or motion in a circular path at constant speed. In some ways, this unit is a continuation of the previous unit on dynamics, but we will introduce new concepts such as angular velocity and acceleration, centripetal force, and the force of gravity.

**Completing this unit should take you approximately 15 hours.**

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

- compare and contrast the physical properties associated with linear motion and rotational motion;
- explain why an object moving at a constant speed in a circle is accelerating;
- apply Newton's law of gravity;
- solve problems involving planets and satellites; and
- explain what it means when an astronaut in earth orbit is described as being "weightless".

### 5.1: Angular Velocity and Acceleration

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

Read sections 6.1 and 6.2 of "Chapter 6: Uniform Circular Motion and Gravitation". Look over the conceptual questions in each section to test your understanding.

Try solving these practice problems.

Work on solving problems 1 through 6 in SAC116 and 1 through 6 in SAC117. The solutions are available, but make a serious attempt to solve the problems before looking at the solutions.

### 5.2: Centripetal Force

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

Read sections 6.3 and 6.4 of "Chapter 6: Uniform Circular Motion and Gravitation". Look over the conceptual questions in each section to test your understanding.

Try solving these practice problems.

Work on solving problems 1, 2, and 3 from SAC119. The solutions are available, but make a serious attempt to solve the problems before looking at the solutions.

### 5.3: Newton's Law of Gravity

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

Read sections 6.5 and 6.6 of "Chapter 6: Uniform Circular Motion and Gravitation". 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 SAC115. The solutions are available, but make a serious attempt to solve the problems before looking at the solutions.

### Unit 5 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