NTA Abhyas JEE Main2020PhysicsWork, Power and EnergyPractice
A chain (mass M ) is hanging from a wooden structure as shown in the figure A . It is slowly taken to a state as shown in the figure B . Calculate the work done by gravity in the process (assume that after reaching the ground, the chain does not form a heap)
Options
- AMg 4 a + π b 4 a 2 + b 2 + a b π
- BMg b 4 a + π b b - a π
- C2 Mg 2 a + π b 4 a 2 - b 2 + ab π
- DMg b 4 a + π b b + a π
Correct answer
D. Mg b 4 a + π b b + a π
Step-by-step solution
Work done by gravity = – (Change in P.E.) ⇒ u i = u linear + u curved = Mass per unit length = M a + π b 4 W gravity = u i - u f = Mgb 4 a + π b b + a π