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

Answer:

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=2.38#Newtons-metre.