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प्रश्न
An electric motor raises a load of 0.2 kg, at a constant speed, through a vertical distance of 3.0 m in 2 s. If the acceleration of free fall is 10 m/s2, the power in W developed by the motor in raising the load is :
पर्याय
0.3
1.2
3.0
6.0
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उत्तर
Mass of the load (m1) = 0.2 kg
Height (h) = 3 m
Acceleration due to gravity (g) =10 m/s2
Time taken (t) = 2s
We can calculate the work done against gravity as,
Work done by the car = (Weight of body) (Vertical distance)
= (0.2)(10)(3) J
= 6 J
Now, we can calculate the power of the boy as,
Power = `"Work done"/"Time"`
So ,
Power = `6/2` W
= 3 W
So, the power is 3 W.
Therefore, the answer is, (c) 3.0
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