A block of mass `m` attached in the lower and vertical spring The spring is hung from a calling and force constant value `k` The mass is released from rest with the spring initially unstreched The maximum value of extension produced in the length of the spring will be

Options

A. 1 Mg / k
B. 2Mg / k
C. 4Mg / k
D. Mg / 2k

Answer

B

Explanation

Work done in max extension = stored P.E.
`implies Mg xx x =1/2 kx^2`
`implies x = (2Mg)/(k)`