Question

a uniform chain of length 2 metres is kept on a table such that the length of 60 centimetres is freely from the edge of the table. The total mass of the Chain is 4kgs. what is the work done in pulling the entire chain on to the table?

Answer 1

The work done is equal to the potential energy of the haning part

so,

W = mgh

here,

m = mass of hanging chain = (60/200) x 4 = 1.2 kg

h = position of center of gravity of hanging chain = 0.30m

so,

W = 1.2x 0.30

thus,

W = 3.6J

Answer 2

Mass of 60 cm part = 60/200 * 4 kg = 1.2 kg

Change in the height of center of mass of 60cm part = 0.30 m

Work done = m g h
= 1.2 * * 0.30 Joules
= 3.6 J