A block of mass m=5 kg is attached with a mass-less spring of force constant k. The block is placed over a fixed rough inclined surface for which the coefficient of friction is 0.75. The block of mass m is initially at rest. The block of mass M is released from rest with spring in un-deformed state. The minimum value of M required to move the block up the plane is (neglect mass of string and pulley and friction in pulley.)