# What torque would have to be applied to a rod with a length of #3 m# and a mass of #4 kg# to change its horizontal spin by a frequency #7 Hz# over #1 s#?

##### 1 Answer

Feb 26, 2017

The torque (for the rod rotating about the center) is

The torque (for the rod rotating about one end) is

#### Explanation:

The torque is the rate of change of angular momentum

The moment of inertiaof a rod, rotating about the center is

The rate of change of angular velocity is

So the torque is

The moment of inertia of a rod, rotating about one end is

So,

The torque is