Physics 9702 · AS & A Level · Energy conservation

Energy conservation — practice question

The diagram depicts a wheel with a circumference of $0.30\,\text{m}$. One end of a rope is attached to a force meter. The rope runs over the wheel and carries a load of $100\,\text{N}$ hanging freely. The wheel is powered by an electric motor and rotates steadily at $50\,\text{revs s}^{-1}$. At this rotational speed, the force meter gives a reading of $20\,\text{N}$. What is the motor's output power?

  • A$0.3\,\text{kW}$
  • B$1.2\,\text{kW}$
  • C$1.8\,\text{kW}$
  • D$3.8\,\text{kW}$

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