Question

A rod of length $L$ and mass $m$ is kept vertically on the ground. Its potential energy is

• A. $mgL$
• B. $mg\frac{L}{2}$
• C. $mg\frac{L}{3}$
• D. $mg\frac{L}{4}$

Answer 1

Answer: (B)

$mg\frac{L}{2}$

Answer 2

The potential energy of the rod will be according to the position of the centre of mass of the rod, which is $\frac{L}{2}$ unit above the ground.
So, potential energy of the rod $=mg\frac{L}{2}$