A chain is placed on smooth table with `(1)/(4)`th of its length hanging over the edge. If the length is 2 m and weight is 4 kg, the energy needed to pull it back to the surface of table is `(g = 10ms^(-2))`:

Options

A. 0.25 J
B. 2.5 J
C. 25 J
D. 50 J

Answer

b

Explanation

When `1/n`th part of the chain is hanging from the edge then work done to pull the chain on table is
`W=(mgl)/(2n^(2))=(mgl)/(2xx(4)^(2))=(mgl)/(32)=(4xx10xx2)/(2)`
W=2.5 J.