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  4. A uniform cable of mass 'M' and length 'L' is placed on a horizontal surface such that its ((1/n))th part is hanging below the edge of the surface. To lift the hanging part of the cable upto the surface, the work done should be :

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Q. A uniform cable of mass $'M'$ and length $'L'$ is placed on a horizontal surface such that its $\bigg(\frac{1}{n}\bigg)^{th}$ part is hanging below the edge of the surface. To lift the hanging part of the cable upto the surface, the work done should be :

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Solution:

Mass of the hanging part = $\frac{M}{n}$
$h_{COM} \, = \, \frac{L}{2n}$
work done W = mgh$_{COM} = \bigg(\frac{M}{n} \bigg) g \bigg(\frac{L}{2n}\bigg) \, = \, \frac{MgL}{2n^2} $
Option (2)

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