Question

A bicycle chain of length $1.6m$ and of mass $1kg$ is lying on a horizontal floor. The work done in lifting it with one end touching the floor and the other end $1.6m$ above the floor is (Take $g=10m{s}^{-2}$):

• A. $10J$
• B. $3.2J$
• C. $8J$
• D. $16J$

Answer 1

The correct option is C $8J$

Consider chain to be concentrated on its center of mass.
Therefore, change in potential energy $=$ work done by external force.
Work done$=mg\frac{h}{2}=8J$