Rotational Motion

In the previous lesson we learned bout circular motion, where an object travels around a circular path.

Now let's learn about rotational motion. This means we're going to describe how an object rotates or spins around its own center (not how it translates through 2D space). It's possible for an object to be rotating and translating at the same time, but we're going to study those motions separately.

Look around and you'll probably find examples of rotational motion: a ceiling fan or desk fan, a clock (the old fashioned kind), a washer or dryer, a door as it opens and closes, wheels on a bike or a car passing by, or even the Earth rotating once a day.

In this lesson we'll learn how to use the angular description of motion. That means we're going to describe rotational motion using, you guessed it, angles! We'll cover angular position, angular displacement, angular velocity and angular acceleration. Although these might seem pretty different than their linear counterparts, we can actually use the same kinematic equations from 1D motion but use angular variables instead.

In the next lesson, we'll bring together circular and rotational motion and learn how to convert between the tangential and angular descriptions of motion.

This lesson covers the kinematics of rotational motion. We'll learn about torque and rotational dynamics later.

Rotational Motion: Using the Angular Description of Motion (18:19)
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Rotational motion examples

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Angular position and displacement

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Angular velocity

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Angular acceleration

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Summary

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Rotational Motion Example Problems (14:29)
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Problem 1: Angular displacement

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Problem 2: Angular velocity

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Problem 3: Angular acceleration

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Problem 4: Constant acceleration equation 1

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Problem 5: Constant acceleration equation 2

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Multiple-Choice Questions

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Introduction

In the previous lesson we learned bout circular motion, where an object travels around a circular path.

Now let's learn about rotational motion. This means we're going to describe how an object rotates or spins around its own center (not how it translates through 2D space). It's possible for an object to be rotating and translating at the same time, but we're going to study those motions separately.

Look around and you'll probably find examples of rotational motion: a ceiling fan or desk fan, a clock (the old fashioned kind), a washer or dryer, a door as it opens and closes, wheels on a bike or a car passing by, or even the Earth rotating once a day.

In this lesson we'll learn how to use the angular description of motion. That means we're going to describe rotational motion using, you guessed it, angles! We'll cover angular position, angular displacement, angular velocity and angular acceleration. Although these might seem pretty different than their linear counterparts, we can actually use the same kinematic equations from 1D motion but use angular variables instead.

In the next lesson, we'll bring together circular and rotational motion and learn how to convert between the tangential and angular descriptions of motion.

This lesson covers the kinematics of rotational motion. We'll learn about torque and rotational dynamics later.

Study Guide
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