The spring block system as shown in the figure is in equilibrium. The string connecting blocks A and B is cut. The mass of all the three blocks is m and the spring constant of both the springs is k. The amplitude of resulting oscillation of block A is
Let x is the
extension of spring just after cutting.
applying Hooke's law,
mg+mg+mg=kx,x=3mgk
The extension in
the spring when the block A in the mean position
=mgk
Amplitude of oscillation of A=3mgk−mgk=2mgk