sphere S of mass M is given a finite angular velocity about a horizontal axis through its centre. Now it is gently placed on a plank p of the same mass. The coefficient of friction between the two is $\mathrm{\mu }$ and the plank rests on a smooth horizontal surface as shown in fig. (6). The initial acceleration of the sphere relative to

the plank will be

• A

  $\mathrm{\mu }$g

• B

  2/5 .$\mathrm{\mu }$g

• C

  2$\mathrm{\mu }$g

• D

  zero