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JEE Main Physics question

PhysicsWork, Energy and PowerJEE Main

A mass of 50 kg is raised through a certain height by a machine whose efficiency is 90%. The energy used is 5000 J. If the mass is now released, its KE on hitting the ground shall be

Answer: (B)

Solution

Useful (potential) energy gained = 90% of 5000 J = 4500 J. On falling back to the ground, this entire PE converts to KE = 4500 J.

Question ID VK-153763