Question

In the Figure, the ball A is released from rest when the spring is at its natural length. For the block B, of mass M to leave contact with the ground at some stage, the minimum mass of A must be:

(A) 2 M

(B) M

(C) M/2 

(D) A function of M and the force constant of the spring

Answer 1

Correct option (C) M/2 

Explanation:

Let m be minimum mass of ball. Let mass A moves downwards by x. From conservation of energy

For mass M to leave contact with ground