When gasoline is burned,it gives off 47,000 J/g of heat energy.If an automobile uses 12.7 kg of gasoline per hour with an efficiency of 24%,what is the average horsepower output of the engine? (1 hp = 746 W)

Question

When gasoline is burned,it gives off 47,000 J/g of heat energy.If an automobile uses 12.7 kg of gasoline per hour with an efficiency of 24%,what is the average horsepower output of the engine? (1 hp = 746 W)
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Quizplus · Accepted Answer

The energy produced per hour is 12,700 g * 47,000 J/g = 596,900,000 J. With 24% efficiency, the useful energy is 0.24 * 596,900,000 J = 143,256,000 J. Power in watts is 143,256,000 J / 3600 s = 39,793.33 W. Converting to horsepower: 39,793.33 W / 746 W/hp ≈ 53 hp.

When Gasoline Is Burned,it Gives Off 47,000 J/g of Heat