# The rate of rotation of a solid disk with a radius of #6 m# and mass of #5 kg# constantly changes from #5 Hz# to #3 Hz#. If the change in rotational frequency occurs over #1 s#, what torque was applied to the disk?

##### 1 Answer

This is a lengthy calculation that requires we first find moment of inertia for the disk, and its angular acceleration, before finding the average torque to be 300

#### Explanation:

To answer this question, we must first determine the rotational inertia of the disk (also called the moment of inertia), *I* :

This will be given by

Similar to Newton's second law F = ma, the corresponding relation for rotational motion is:

*I*

To find

The change in angular velocity is 2 Hz x 2

Finally,