An engineer claims to have perfected the gasoline combustion engine. According to his calculations, for every gallon of gasoline burned (which releases about 120 MJ of heat), 70 MJ of work can be done by his engine. Do you believe the engineer? Why or why not? Justify your answer using physics Solution According to the data given, the thermal efficiency of the engine = Energy used as work / Total energy supplied ==> Thermal Efficiency = 70 MJ / 120 MJ ==> 0.5833 This implies that the engine is 58.33 percent efficient, which is highly unlikely to be true in practical terms. The range of eff. for modern day\'s gasoline engines is between 20-50 percent. However if made hybrid with an electric system, a better efficiency can be achieved. .

1. An engineer claims to have perfected the gasoline combustion engine. According to his
calculations, for every gallon of gasoline burned (which releases about 120 MJ of heat), 70 MJ of
work can be done by his engine. Do you believe the engineer? Why or why not? Justify your
answer using physics
Solution
According to the data given, the thermal efficiency of the engine = Energy used as work / Total
energy supplied
==> Thermal Efficiency = 70 MJ / 120 MJ ==> 0.5833
This implies that the engine is 58.33 percent efficient, which is highly unlikely to be true in
practical terms.
The range of eff. for modern day's gasoline engines is between 20-50 percent. However if made
hybrid with an electric system, a better efficiency can be achieved.