Physics 9702 · AS & A Level · Potential difference and power

Potential difference and power — practice question

A crane is used to raise containers from a ship. One container has a mass of $14\,000\text{ kg}$ and is being moved upwards at a speed of $3.2\text{ m s}^{-1}$. The electric motor that provides the power for lifting the container takes a current of $240\text{ A}$ at a potential difference of $2200\text{ V}$. Calculate the efficiency of the system.

  • A$8.1\%$
  • B$8.5\%$
  • C$48\%$
  • D$83\%$

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