When gasoline is burned,it gives off 46 000 J/g of heat energy.If an automobile uses 13.0 kg of gasoline per hour with an efficiency of 21%,what is the average horsepower output of the engine? (1 hp = 746 W)

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The average horsepower output of the engine is 47 hp.The energy released by burning 13.0 kg of gasoline is 13.0 kg * 46 000 J/g = 598 000 000 J. The efficiency of the engine is 21%, so the useful energy output is 0.21 * 598 000 000 J = 125 580 000 J. The average horsepower output is 125 580 000 J / (746 W * 3600 s) = 47 hp.

When Gasoline Is Burned,it Gives Off 46 000 J/g of Heat