# A 2500 kg car accelerates from rest to a velocity of 10 m/s in 5.0 seconds. The power of the engine during this acceleration is?

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- billrussell42Lv 710 months ago
KE = ½mV² = ½2500•10² = 125000 J

power = energy/time = 125000/5 = 25000 W or 25 kW

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- oubaasLv 710 months ago
accelerating force F = m*a = 2500*V/t = 2500*10/5 = 5000 N

initial power Pi = F*Vi = 5000*0 = 0

final power Pf = F*Vf = 5000*10/1000 = 50.0 kw

average power Pav = (Pi+Pf)/2 = (50.0+0)/2 = 25.0 kw

or

KE = m*V^2/2 = 2500*10^2/2000 = 125 kjoule

Pav = KE/t = 125/5 = 25.0 kw

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