An engine accelerates a car of mass 800 kg to a speed of $72\ kmh^{- 1}$. If the frictional force is 10 M per ton, the power developed by the engine is

Question

Dr. Abubacker · Accepted Answer

(d) Speed of car, $v = 72\ kmh^{- 1}\  = \ 72 	imes \frac{5}{18} = 20\ ms^{- 1}$
$KE\  = \frac{1}{2}mv^{2} = \frac{1}{2} 	imes 800 	imes 400$
$= 400 	imes 400\ J$
$P = \frac{KE}{time} = \frac{400 	imes 400}{32}$
$= \ 5000\ W\  = \ 5\ kW$

Q. An engine accelerates a car of mass 800 kg to a speed of $72\ kmh^{- 1}$. If the frictional force is 10 M per ton, the power developed by the engine is

Explanation

Reviewed by Dr. Abubacker

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