A massless spring with a force constant `K = 40N//m` hangs vertically from the ceiling.A `0.2 kg` block is attached to the end of the spring and held in such a position that the spring has its natural length and suddenyl released. The maximum elastic strain energy stored in the spring is `(g=10 m//s^(2))`

Options

A. `0.1J`
B. `0.2J`
C. `0.05J`
D. `0.4J`

Answer

B

Explanation

`PE = (1)/(2)kx^(2),x = 2(mg)/(k)`