### 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.**

### 5.1: Angular Velocity and Acceleration

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

This resource illustrates the connection between uniform circular motion and the simple harmonic motion associated with Hooke's Law.

Read sections 6.1 and 6.2 of "Chapter 6: Uniform Circular Motion and Gravitation" (pages 187 to 194). Look over the corresponding conceptual questions on page 214 to test your understanding of the sections.

Try solving these practice problems.

Study the animation, which illustrates the rule for determining the direction of the angular velocity vector.

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" (pages 194 to 201). Look over the corresponding conceptual questions on pages 214-216 to test your understanding of the sections.

Try solving these practice problems.

The mass is constrained to move in a vertical circle while feeling the effects of Earth's gravity. Determine how the tension on the string must vary to make this happen as shown.

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" (pages 201 to 212). Look over the corresponding conceptual questions on page 216 to test your understanding of the sections.

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

Please take this assessment to check your understanding of the materials presented in this unit.

**Notes:****There is no minimum required score to pass this assessment, and your score on this assessment**__will not__factor into your overall course grade.**This assessment is designed to prepare you for the Final Exam that will determine your course grade. Upon submission of your assessment you will be provided with the correct answers and/or other feedback meant to help in your understanding of the topics being assessed.****You may attempt this assessment as many times as needed, whenever you would like.**