Physics · Oct / Nov 2023 · Paper 12 · Question 14

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?

1. Aefficiency = \frac{\text{GPE gained per second}}{\text{KE gained per second}}
2. Befficiency = \frac{\text{GPE gained per second}}{\text{power supplied}}
3. Cefficiency = \frac{\text{power supplied}}{\text{GPE gained per second}}
4. Defficiency = \frac{\text{power supplied}}{\text{KE gained per second}}

As printed in the paper