# What torque would have to be applied to a rod with a length of #7 m# and a mass of #9 kg# to change its horizontal spin by a frequency #12 Hz# over #16 s#?

##### 1 Answer

Feb 21, 2017

The torque (about the center) is

The torque (about one end) is

#### Explanation:

The torque is the rate of change of angular momentum

The moment of inertia of a rod, rotating abour the center is

The rate of change of angular velocity is

So the torque is

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

So,

The torque is