✔ 最佳答案
In this question, you can use the formula:
Power = Force x velocity
The above formula is suitable for "uniform velocity motion" and "uniform acceleration motion".
In uniform velocity motion, the velocity is a constant. The case is simple.
In uniform acceleration motion, the velocity is varied in uniform acceleration. The velocity used in the above formula is the "average velocity" of the motion, i.e.
Power = Force x (average velocity)
The question involves uniform acceleration motion. Therefore, "average velocity" should be used in the above formula. The average velocity can be calculated in either of the following two ways:
(1) Average velocity = (u + v)/2 = (0 + 12)/2 = 6 m s-1
(2) Average velocity = displacement/time = 24/4 = 6 m s-1
You have made confusion because you took v (the final velocity) as the average velocity.
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