A centrifuge rotor rotating at 12000 rpm is shut off and is eventually brought to rest by a frictional torque of 1.50 m·N. If the mass of the rotor is 4.80 kg and it can be approximated as a solid cylinder of radius 0.0710 m, through how many revolutions will the rotor turn before coming to rest? How long will it take?

1 answer

a. calculate the moment of inertia for the rotor (solid cylinder). Personnally, I recmmmend changing rpm to radians/sec

Torque=momentI* angular acceleration
solve for angular acceleration.

Then,
wfinal=winitial+ angAcc*time
solve for time

displacement=winitial*time+1/2 angacc;*time^2
solve for displacement in radians, divide by 2PI to get revolutions.