JEE Main Physics question
A 10 m long iron chain of linear mass density 0.8 kg m⁻¹ is hanging freely from a rigid support. If g = 10 ms⁻², then the power required to lift the chain up to the point of support in 10 s is
Answer: (D)
Solution
Mass of chain = 0.8×10 = 8 kg, with its centre of mass 5 m below the support. Work = mgh = 8×10×5 = 400 J. Power = 400/10 = 40 W.