To the free end of spring hanging from a rigid support, a block of mass m is hung and slowly allowed to come to its equilibrium position. Then, stretching in the spring is d. If the same block is attached to the same spring and allowed to fall suddenly, the amount of stretching is (force constant k)

Options

A. mg/k
B. 2d
C. mg/3k
D. 4 d

Answer

b

Explanation

If the maximum extension in a spring at extrem position of block is x1 then,
Work done by weight of the block =potential energy in the spring
mg `x=1/2kx^(2) x=2mg/k=2d`