Two bodies of mass m and 4m are attached by a string shown in the figure-2.146. The body of mass m hanging from a string of length l is executing simple harmonic motion with amplitude A while other body is at rest on the surface. The minimum coefficient of friction between the mass 4m and the horizontal surface must be to keep it at rest is :

Options

A. `(1)/(4)(1-(A^(2))/(l^(2)))`
B. `(1)/(4)(1+(A^(2))/(l^(2)))`
C. `(1)/(4)(A)/(l)costheta`
D. `(1)/(4)`

Answer

B