Suppose a car travels 108 km at a speed of 30.0 m/s, and uses 1.90 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 1.30 ✕ 108 j per gallon.)
(a) what is the force (in n) exerted to keep the car moving at constant speed? 2287.0 n
(b) if the required force is directly proportional to speed, how many gallons will be used to drive 108 km at a speed of 28.0 m/s? gallons.