When gasoline is burned,it gives off 41 000 J/g of heat energy.If an automobile uses 14.1 kg of gasoline per hour with an efficiency of 23.0%,what is the average horsepower output of the engine? (1 hp = 746 W)

Question

Quizplus · Accepted Answer

First, convert the mass of gasoline to grams (14.1 kg * 1000 g/kg = 14100 g). Then, calculate the total energy produced per hour by multiplying the energy content of gasoline (41,000 J/g) by the mass consumed (14100 g), which equals 578,100,000 J/h. Since the engine operates at 23.0% efficiency, the useful energy output is 23.0% of 578,100,000 J, which is 132,963,000 J/h. Converting J/h to watts (W) by dividing by 3600 s/h gives 36,934 W. Finally, converting watts to horsepower (1 hp = 746 W) gives 36,934 W / 746 W/hp = 49.5 hp.

When Gasoline Is Burned,it Gives Off 41 000 J/g of Heat