Question

A chain is placed on a frictionless table with one fourth of it hanging over the edge. If the length of the chain is 2m and its mass is 4kg, the energy need to be spent to pull it back to the table is

• A. 32 J
• B. 16 J
• C. 10 J
• D. 2.5 J

Answer 1

Answer: (D)

2.5 J

Answer 2

$W = \frac { M g L } { 2 n ^ { 2 } }$ $= \frac { 4 \times 10 \times 2 } { 2 \times ( 4 ) ^ { 2 } } = 2.5 \mathrm {~J}$