A disk of radius 25 cm spinning at a rate of 30 rpm slows to a stop over 3 seconds. What is the angular acceleration? B. How many radians did the disk turn while stopping ? C. how many revolutions?
30 rev/min(2pi rad)/(60 sec/min)=pi rad/s
A= delta(w)/t=(0-pi)/3=pi/3 rad/s^2
Theta=1/2at^2=1/2(pi/3)3^2=1.5pi radians
Theta= 1.5pi rad/2pi rad/rev=0.75 rev
Is this correct if not correct me if I'm wrong.