If the shaft is rotating at 100rpm, the mass is

Question

Masses $B_{1}, B_{2}$  and 9kg are attached to a shaft in parallel planes as shown in the below figure. If the shaft is rotating at 100rpm, the mass  $B_{2}$ is              

(a) 3 kg                           (b) 6 kg            

(c) 9 kg                         (d) 27 kg