posted by Christina .
A CD rotates at 500 (revolutions per minute) while the last song is playing, and then spins down to zero angular speed in 2.60 seconds with constant angular acceleration. The magnitude of the angular acceleration of the CD, as it spins to a stop is 20.1 radians per second squared.
How many complete revolutions does the CD make as it spins to a stop?
displacement=wi*time + 1/2 a*t^2
displacement is in radians, it is what you seek. Wi = 500*2PI/60 rad/sec
a= -20.1 rad/s^2
Now for time, which is given.