O-LevelPhysicsEnergy & Work5054/12 · Oct/Nov 2023 · Q141 Mark

An electric motor is used to lift a load at a constant speed. The gravitational potential energy (GPE) stored in the load increases. The moving load also has stored kinetic energy (KE). Which expression is used to calculate the efficiency of the motor when the load is being lifted at a constant rate?

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Aefficiency = GPE gained per second / KE gained per second

Befficiency = GPE gained per second / power supplied

Cefficiency = power supplied / GPE gained per second

Defficiency = power supplied / KE gained per second

✓ Correct answer

B: efficiency = GPE gained per second / power supplied

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Topic: Energy & Work, O-Level Physics (syllabus 5054). Multiple choice, 1 mark.
Source: O-Level Physics, Oct/Nov 2023 Paper 1 Variant 2, question 14.

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