A solid disk with a radius of 3 m and mass of 4 kg is rotating on a frictionless surface. If 120 W of power is used to increase the disk's rate of rotation, what torque is applied when the disk is rotating at 8 Hz?

1 Answer
Nov 19, 2016

The torque applied is 2.38 N-m.

Explanation:

This goes very simple, Power is the product of the torque and angular velocity, similar to P=Fv.
=>P=tauomega
So here angular acceleration comes with omega=2pinu.
Calculating the angular velocity with given frequency we get,
omega=50.24rads^-1
Now the above power equation becomes
=>tau=P/omega
Substituting the given values we get,
tau=(120W)/(50.24rads^-1).

:. tau=2.38Newtons-metre.