A block of mass m is connected to another block of mass M by a spring (massless) of spring constant k. The block are kept on a smooth horizontal plane. Initially the blocks are at rest and the spring is unstretched. Then a constant force F starts acting on the block of mass M to pull it. Find the force of the block of mass M.

Options

A. `(MF)/(m+M)`
B. `(mF)/(M)`
C. `((M+m)F)/(m)`
D. `(mF)/(m+M)`

Answer

D

Explanation

Acceleration of the system of two masses is
` a=(F)/(m+M)`
Force on the block of mass `m=ma=(mF)/( m+M)`