Question

A smooth chain of length 2 m is kept on the table such that its 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. ( Take g = 10 m/s2)

• A. 3.6 J
• B. 12.9 J
• C. 2.0 J
• D. 6.3 J

Answer 1

Answer: (A)

3.6 J

Answer 2

Given:
Length of the chain = 2 m
Length of the hanging part = 60 cm = 0.6 m
Total mass of the chain = 4 kg
Acceleration due to gravity (g) = 10 m/s²
First, let's calculate the potential energy of the hanging part of the chain.
Potential energy (PE) = mass × gravitational acceleration × height
Since the hanging part of the chain is hanging freely, its height is 0.6 m.
PEhanging = masshanging × g × heighthanging
= (0.6 kg) × (10 m/s²) × (0.6 m)
= 3.6 J
Next, let's calculate the potential energy of the entire chain when it is on the table.
The mass of the entire chain is 4 kg, and the height of the entire chain is 0 (since it is on the table).
PEtable = masstable × g × heighttable
= (4 kg) × (10 m/s²) × (0 m)
= 0 J
The work done in pulling the entire chain on the table is the difference between the initial potential energy (PEhanging) and the final potential energy (PEtable).
Work done = PEhanging - PEtable
= 3.6 J - 0 J
= 3.6 J
Therefore, the work done in pulling the entire chain on the table is 3.6 J. The correct option is (A) 3.6 J.