Question

A uniform chain of length 2m is kept on a table such that a length of 60cm 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

Answer 1

The correct option is B 3.6 J

Now,

Work done in pulling the chain on the table

As we know if we pull the chain, each part of the chain will not cover same height, therefore will not contribute the same potential energy, so let's take mass of the chain $L^{\prime }=\frac{L}{2n}$

Now we can write
$W=\frac{mgL}{2n^2}$

AFter putting all the values and solving
$=\frac{4\times 10\times 2}{2\times (\frac{10}{3}{)}^2}=3.6J$

Hence the work done in pulling the chain is 3.6 J