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 4 kg.  What is the work done in pulling the entire chain on the table ?

The center of gravity of the hanging part is at  0.3 m from table.   ∴   mass of hanging part of chain  =   4×0.62  =   1.2kg    ∴  Work done in pulling the entire chain on to the table=(mass of hanging part)g(center of gravity of hanging part)  =    mgh  =   1.2 x 10 x 0.3  =   3.6 Jh= height through which the centre of mass of the hanging part moved on pulling.