A CD has a mass of 17 g and a radius of 6.0 cm. When inserted into a player, the CD starts from rest and accel

Question

A CD has a mass of 17 g and a radius of 6.0 cm. When inserted into a player, the CD starts from rest and accelerates to an angular velocity of 23 rad/s in 0.86 s. Assuming the CD is a uniform solid disk, determine the net torque acting on it.

Answer 1

The moment of inertia of the disk is 0.5*m*r^2 (ref.). (In kg-m-s units, m=.017 and r=.06.) The average angular acceleration A=23/0.86 rad/s^2. The torque T is the product of moment of inertia and angular acceleration. T=0.5*m*r^2*23/0.86 N-m.