# What torque would have to be applied to a rod with a length of #5 m# and a mass of #12 kg# to change its horizontal spin by a frequency #8 Hz# over #7 s#?

##### 1 Answer

Oct 30, 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 inertia of a rod, rotating about the center is

The mass of the rod is

The length of the rod 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