Question

Two points are on a disk turning at constant angular velocity. One point is on the rim and the other halfway between the rim and the axis. Which point moves the greater distance in a given time?

Answer 1

Answer:

The point on the rim

Explanation:

All the points on the disk travels at the same angular speed $\omega$, since they cover the same angular displacement in the same time. Instead, the tangential speed of a point on the disk is given by

$v=\omega r$

where

$\omega$ is the angular speed

r is the distance of the point from the centre of the disk

As we can see, the tangential speed is directly proportional to the distance from the centre: so the point on the rim, having a larger r than the point halway between the rim and the axis, will have a larger tangential speed, and therefore will travel a greater distance in a given time.