Our discussion of rotational motion begins with a review of the measurement of angles using the concept of radians. We will refer to an angle measured in radians as an angular distance. If we are discussing an object that is rotating, we will describe the rotation in terms of the increase in angular distance, namely an angular velocity. And if the speed of rotation is changing, we will describe the change in terms of an angular acceleration.

Topical Notes, Topical Notes, Problems, Presentations, Quiz, Test, Investigations, and Videos |

Torque |

Center of mass |

Rotational Kinematics |

Rotational Dynamics and Rotational inertia |

Rotational Energy |

Angular Momentum |

Conservation of Angular Momentum |

Test your Understanding: Chapter 5 MCQ Quiz 1 Here Take Chapter 5 ReQuiz MCQ Quiz 2 Here |

The main point of this chapter is to develop a close analogy between the two concepts. The linear momentum of an object is its mass m times its linear velocity v. We will see that angular momentum can be expressed as an angular mass times an angular velocity. (Angular mass is more commonly known as moment of inertia). Then, using the formalism of the vector cross product, we will see that angular momentum can be treated as a vector quantity, which explains the bicycle wheel experiments.

Our focus in this chapter is on angular momentum because that concept will play such an important role in our later discussions of atomic physics and electrons and nuclear magnetic resonance.