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A car of mass `500kg` moving with a speed `36kmh` in a straight road unidirectionally doubles its speed in `1min`. Find the power delivered by the engine.A. 1250 WB. 1250 HPC. 625 WD. 625 HP |
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Answer» Correct Answer - A Its initial speed `v_(1)=(36000)/(3600) =10ms^(-1)` If the car doubles its speed, finally its speed becomes `v^(2) =20ms^(-1)` Change in KE of the car `=Delta KE =(1//2)` `mv_(2)^(2) -(1/2)mv_(1)^(2)` During Dt = 1 min = 60 s the power delivered by the engine, `P=("Work done")/("Time taken") =(|Delta KE|)/(Delta t)` `=((1)/(2) xx m [v_(2)^(2) -v_(1)^(2)])/(Delta t) =(1//2 xx 500 [20^(2)-10^(2)])/(60)` `=1250 W` |
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