Efficiency and power Quiz
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5 questions, one answer each
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1. A machine takes in 800 J and transfers 600 J usefully. What is its efficiency?
- A. 25%
- B. 60%
- C. 75%
- D. 133%
2. What is the unit of power?
- A. Joule
- B. Watt
- C. Newton
- D. Percent
3. A motor transfers 2400 J in 8 s. What is its power?
- A. 300 W
- B. 19 200 W
- C. 0.0033 W
- D. 2392 W
4. Which action would increase the efficiency of a bicycle?
- A. Removing the oil from the chain
- B. Oiling the chain and wheel bearings
- C. Using a heavier frame
- D. Letting the tyres go flat
5. Which statement about wasted energy is correct?
- A. It is destroyed
- B. It is usually transferred to the thermal store of the surroundings
- C. It is always transferred as sound
- D. It increases the efficiency