Question

A unform chain of length L and mass M is lying on a smooth table and one third of its length is hanging vertically down over the edage of the table. What is the work done required to pull hanging part on to the table

Answer 1

I give you its formula then you solve this type question easily .
if A chain of length L and mass M .A part L/n is hanging at the edge of the table .
the length of chain on the table is (L- L/n) .then , workdone against gravity to pull the hanging part on the table =MgL/2n^2

now ,
a/c to question one third part hanging at the edge of the table.
so,

workdone =MgL/2 (3)^2 =MgL/18