Table 6.4.1: Linear vs. Angular Equations

These editorial refreshers supplement the reading. Definitions and examples are added guidance; original source wording and recorded answers remain in their original context.

• Angular momentum

  Angular momentum describes motion about a specified point or axis. For rigid rotation about a fixed principal axis it can be written as rotational inertia times angular velocity; a translating particle can also have angular momentum about a point. For example, a ball moving past a pole has angular momentum about the pole even though the ball’s path is straight.

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• Linear momentum

  Linear momentum is a vector describing an object’s motion and equals mass times velocity in the nonrelativistic model. The vector sum of momenta is conserved when the net external impulse on the system is zero. For example, two identical carts moving equally fast in opposite directions have zero total linear momentum but nonzero total kinetic energy.

  Read more: Momentum →