Question

A block of mass m is connected to another block of mass M by a spring (massless) of spring constant k. The blocks 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.

(a)  MF/(m + M)

(b) mF/M

(c) (M + m)F/m

(d) mF/(m + M)

Answer 1

(d) : Acceleration of the system a = F/(m + M)

Force on block of mass m = ma = mF/(m + M).