An object of mass 20 kg starts from rest and reaches a velocity of 10 m/s in 10 seconds. Calculate the power expended by the object.

100 w

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100 W

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200 W

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300 W

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Solution

The correct option is B 100 W
Mass m = 20 kg
Initial velocity u $= 0 m / s$ ,
Final velocity v $= 10 m / s$
Time taken, t = 10 sec.
Work done = Change in kinetic energy
Change in K.E. $= \frac{1}{2} m (v^{2} - u^{2})$
$= \frac{1}{2} \times 20 (10^{2} - 0^{2})$
= 1000 J
Power, P = work done per second
$= \frac{W}{t}$
$= \frac{1000}{10}$
$= 100 \frac{J}{s}$ or 100 W

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An object of mass 20 kg starts from rest and reaches a velocity of 10 m/s in 10 seconds. Calculate the power expended by the object.

The correct option is B 100 WMass m = 20 kg Initial velocity u =0m/s, Final velocity v =10m/s Time taken, t = 10 sec. Work done = Change in kinetic energy Change in K.E. =12m(v2−u2) =12×20(102−02) = 1000 J Power, P = work done per second =Wt =100010 =100Js or 100 W