Q. In the figure, the ball is released from rest when the spring is at its natural (unstretched) length. For the block of mass to leave contact with the ground at some stage, the minimum mass of must be

Question

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Solution:

The spring will exert maximum force when the ball is at its lowest position. If the ball has descended through a distance to reach the position.
or .....(i)
For block to leave contact spring force, .....(i)
Comparing equations (i) and (ii),