Two block of masses M and m are connected to each other by a massless string and spring of force constant k as shown in the figure. The spring passes over a frictionless pulley connected rigidly to the egde of a stationary block A. The coefficient of friction between block M and plane horizontal surface of A is `mu`. The block M slides over the horizontal top surface of A and block m slides vertically downward with the same speed. The mass M is equal to

Options

A. `(m)/(mu)`
B. `(2m)/(mu)`
C. `mmu`
D. `mu mg`

Answer

A

Explanation

(a) When the system of two block of masses M and m is either at rest on moving with the same speed, no net force acts on them, In this equilibrium state.

`T=mu R=mu Mg" and " T=mg`
`therefore " " mu Mg=mg implies M=(m)/(mu)`