# Suppose a car travels 108 km at a speed of 30.0 m/s, and uses 2.10 gallons of gasoline. Only 30% of the gasoline goes into useful work by the force that keeps the car moving at constant speed despite friction. (The energy content of gasoline is 1.3 ✕ 108 J per gallon.)

# Suppose a car travels 108 km at a speed of 30.0 m/s, and uses 2.10 gallons of gasoline. Only 30% of the gasoline

goes into useful work by the force that keeps the car moving at constant speed despite friction. (The energy content of gasoline is 1.3 ✕ 10^{8} J per gallon.)