A Brake Pad Is Used to Give a Normal Force

Multiple Choice

A brake pad is used to give a normal force of 150N to the outer surface of a 0.25kg spinning disk,in order to slow it down from 250rpm to rest.The disk's radius is 0.25m.If the coefficient of friction between the pad and the disk is 0.45,how much time was required for the disk to slow from 250 rpm to rest?

A) 0.19s
B) 0.55s
C) 2.4s
D) 12s