A car is driven along a level road. The total energy input from the petrol is 60kJ and the car wastes 45kJ of energy. What is the efficiency of the car?
Correct answer: A. 25%
- A. 25%
- B. 15%
- C. 45%
- D. 75%
Explanation
The explanation of this question is: Since the car wastes 45kJ of energy, it uses 60 - 45 = 15 kJ Efficiency = output energy/input energy x 100 15/60 x 100 = 25 %
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About Work and Energy
Work transfers energy when a force causes displacement, while kinetic energy, gravitational potential energy and power describe motion, position and the rate of energy transfer. The work-energy theorem links net work with change in kinetic energy, and efficiency accounts for energy losses rather than treating them as energy destruction.
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