An engine pulls a car of mass 1500 kg on a level road at a constant speed of 5 ms-1. If the frictional force is 500 N, what power does the engine generate?
Correct answer: B. 2.5 kW
- A. 5.0 kW
- B. 2.5 kW
- C. 10 kW
- D. 12.5 kW
Explanation
Since the car is moving with a constant speed, there is no chnage in KE ;hence, the power generated is due to the frictional force acting on it, so we use the following formula in this case: P = Fv = 500 x 5 = 2500= 2.5 kW
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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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