An elevator lifts a weight of 400 N through a height of 10 m in 20 s. The power of the motor is
Correct answer: A. 200 W.
- A. 200 W.
- B. 800 W.
- C. 4000 W.
- D. 8000 W.
Explanation
To calculate the power of the motor, you need to find the work done and then divide it by the time. Work Done is calculated as Force multiplied by Distance. Here, Work Done = 400 N * 10 m = 4000 J (Joules). Power is then Work Done divided by Time: Power = 4000 J / 20 s = 200 W. Therefore, the correct answer is 200 W. Options B, C, and D result from incorrect applications of the power formula, either miscalculating Work Done or incorrectly dividing by Time.
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About Power
Power is the rate at which work is done or energy is transferred, with average power calculated over a time interval and instantaneous power found from P = Fv when force and velocity are aligned. Work includes units, mechanical efficiency, and the distinction between power and total work or energy.
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