A grandpa travels along the freeway, going 60 mph. A young hotshot travels along the freeway in a car of the same make and model, going 90 mph. Both cars deliver the same fraction of gasoline energy to the drivetrain, and in both cases, almost all of that energy gets converted to thermal energy via drag as follows: (energy dissipated) =(drag force) x (distance traveled).
(i) What two horizontal forces are approximately balanced for a car traveling along the freeway at constant speed?
(ii) Using the formula drag force = (constant) x (speed)n with the appropriate value of n based on class discussion, if both cars make the same trip at their respective speeds, what is hotshot's gas mileage relative to grandpa's? Express as a percentage.