Rankers Physics

Potential Energy & Equilibrium: Practice Problem & Solution

A uniform chain has a mass m and length l. It is held on a frictionless table with one-sixth of its length hanging over the edge. The work done in just pulling the hanging part back on the table is
mgl/72
mgl/36
mgl/12
mgl/6

Short Solution (Best for NEET):

To solve this problem, we apply the core principles of Potential Energy & Equilibrium. Understanding the underlying formula is key to arriving at the correct answer below:

mass of hanging portion = m/6

Potential energy of handing portion = m/6×g×(-l/12)= -mgl/72

Work done by external agent is negative of change is Potential Energy = mgl/72

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