Quick questions on Power and efficiency (QCE Physics Unit 2)

3short Q&A pairs drawn directly from our worked dot-point answer. For full context and worked exam questions, read the parent dot-point page.

What is q1?

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Define power and state two equivalent algebraic forms. [2 marks]

What is q2?

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A motor lifts a

200 \text{ kg}

load

15 \text{ m}

20 \text{ s}

. Calculate the useful output power. If input power is

1.8 \text{ kW}

, calculate the efficiency.

What is q3?

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A Cairns tram induction motor delivers

200 \text{ kW}

14 \text{ m s}^{-1}

. (a) Calculate the traction force. (b) Given

230 \text{ kW}

electrical input, determine the efficiency and the power lost.

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