Problem

A spring of natural length

l

is compressed vertically downward against the floor so that its compressed length becomes

\frac{l}{2}

. On releasing, the spring attains its natural length. If

k

is the stiffness constant of spring, then the work done by the spring on the floor is a. zero b.

\frac{1}{2}kl^2

\frac{1}{2}k\left(\frac{l}{2}\right)^2

kl^2