Question

A uniform chain of length 2 m 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 4 kg. 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

Here, mass of the chain = 4 kg, length of the chain = 2 m, length of the chain hanging freely = 60 cm = 0.6 m

Therefore, mass of the hanging chain m = $\frac{4}{2}\times 0.6=1.2kg$

To pull the entire chain on the table, the C.G. of the hanging part has to be raised to the table i.e., hanging part has to be raised through a distance $h=\frac{0.6}{2}=0.3cm$

Therefore, work done, $W=mgh=1.2\times 10\times 0.3=3.6J$