Question

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. $\frac{1}{2}k{l}^2$
• C. $\frac{1}{2}l(\frac{1}{2}{)}^2$
• D. $k{l}^2$

Answer 1

The correct option is A Zero

Only the center of mass of the spring changes, but the floor has no displacement.
Hence the work done by the spring on the floor is zero.
Option A.