Question

When a block of mass $M$ is suspended by a long wire of length $L$. the length of the wire becomes $(L+ l)$. The elastic potential energy stored in the extended wire is:

• A. $\frac{1}{2}Mgl$
• B. $\frac{1}{2}MgL$
• C. $mgl$
• D. $MgL$

Answer 1

Answer: (A)

$\frac{1}{2}Mgl$

Answer 2

$U = \frac{1}{2}$ (work done by gravity)
$U = \frac{1}{2} Mgl$