An older-model car accelerates from 0 to speed v in a time interval of δt. a newer, more powerful sports car accelerates from 0 to 5v in the same time period. assuming the energy coming from the engine appears only as kinetic energy of the cars, compare the power of the two cars.

Question

Physics

Kaylie Hunt

19 March, 07:26

An older-model car accelerates from 0 to speed v in a time interval of δt. a newer, more powerful sports car accelerates from 0 to 5v in the same time period. assuming the energy coming from the engine appears only as kinetic energy of the cars, compare the power of the two cars.

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Justin Blake · Answer 1

Power = Energy / time = Δ kinetic energy / time = ΔKE / t

For old car: ΔKE = m (v^2) / 2 = > Power = m (v^2) / (2t)

For new car: ΔKE = m (5v) ^2 / 2 = > Power = 25 * [ m (v^2) / (2t) ]

Then, comparing the expressions for both cars, you get that the power of the new car is 25 times the power of the old car.