A uniform disc of mass M and radius R initially stands vertically on the right end of a horizontal plank of mass M and length L, as shown,

The plank rests on a smooth horizontal floor and friction between disc and plank is sufficiently high such that disc rolls on plank without slipping . The plank is pulled to right with a constant horizontal force of magnitude F.
The distance travelled by centre of disc from its initial position till the left end of plank comes vertically below the centre of disc is

Options

A. `(L)/(2)`
B. `(L)/(4)`
C. `(L)/(8)`
D. L

Answer

A