http://www.ck12.org Chapter 10. Rotational Motion Version 2
10.1 The Big Idea
In the chapter on centripetal forces, we learned that in some situations, objects move in circles. The purpose of this
chapter is to describe and formalize such motion. The fundamental physics behind it is based on theconservation
of angular momentum.This vector quantity is the product of rotational velocity and rotational inertia. In any closed
system (including the universe) the quantity of angular momentum is fixed. Angular momentum can be transferred
from one body to another, but cannot be lost or gained. If a system has its angular momentum changed from the
outside it is caused by a torque. Torque is a force applied at a distance from the center of rotation.
Rotational motion has many analogies to linear motion. By studying it in this framework, we can make use of many
of our previous results. In fact, most of rotational motion can be understood by looking at the following figure and
applying results from previous chapters.