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.  The work done in pulling the entire chain on the table is

Mass per unit length = $\frac{\text{M}}{\text{L}}$

= $\frac{4}{2}=2\text{kg}{\text{m}}^{-1}$          

The mass of 0.6m of chain = $0.6\times 2=1.2\text{kg}$

$\therefore$ Center of mass of hanging part $\text{h}=\frac{0.6+0}{2}=0.3\text{m}$

Hence, work done in pulling the chain on the table = work done against the gravity force

$\text{W}=\text{mgh}=1.2\times 10\times 0.3=3.6\text{J}$