Question

http://gyazo.com/cbc109c5307bf8034faa52ac631a7c8d

Could you help me with this problem?
I can understand bits of it, but I can't put it together into a single formula

Answer 1

here theta is the angular displacement occuring to the disks by the time the bullet covers distance D. given the velocity of the bullet is v and then time t taken by the bullet to reach the second disk from first is t = D/v
given time period of rotation of the disks id T. hence its angular velocity w=2pi/T
angualar displacement by time t is theata. hence theat is wt
wt= 2pi/T * D/v