Question

A chain of length L is released from rest, from a frictionless surface with half length hanging as shown in figure. Work done by gravity when the chain is just completely off the surface.
(m=10 kg, g=10 $m/s^2$ and L=10 $m$)

• A. 475 J
• B. 375 J
• C. 250 J
• D. 75 J

Answer 1

The correct option is B 375 J

Work done by gravity = change in potential energy
$=\frac{mgl}{2}-\frac{mgl}{4}$$=\frac{3mgl}{8}=375$J