Physics 5054 · O Level · Efficiency

Efficiency — practice question

An electric motor is employed to raise a load at constant speed. The gravitational potential energy (GPE) stored in the load rises. The moving load also possesses kinetic energy (KE). Which expression is used to calculate the efficiency of the motor while the load is lifted at a constant rate?

  • A$\text{efficiency} = \frac{\text{GPE gained per second}}{\text{KE gained per second}}$
  • B$\text{efficiency} = \frac{\text{GPE gained per second}}{\text{power supplied}}$
  • C$\text{efficiency} = \frac{\text{power supplied}}{\text{GPE gained per second}}$
  • D$\text{efficiency} = \frac{\text{power supplied}}{\text{KE gained per second}}$

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