Q. A uniform chain of length $2m$ is kept on a table such that a length of $60\ cm$ hangs freely from the edge of the table. The total mass of the chain is $4kg$. What is the work done in pulling the entire chain on the table
A) $7.2\ J$
B) $3.6\ J$
C) $120\ J$
D) $1200\ J$
Explanation
(b) Fraction of length of the chain hanging from the table
$= \frac{1}{n} = \frac{60\ cm}{200\ cm} = \frac{3}{10} \Rightarrow n = \frac{10}{3}$
Work done in pulling the chain on the table
$W = \frac{mgL}{2n^{2}}$
$= \frac{4 \times 10 \times 2}{2 \times (10/3)^{2}} = 3.6\ J$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.