Consider a car having a frontal are of 2.0m^2 with a drag coefficient of 0.35. The mass of the car is 1250kg and the rolling resistance is 1.0% of the weight of the car.
1. At what speed does the aerodynamic drag first exceed the rolling resistance.
2. Calculate the ratio of the power that is required for the car ravelling at 90 miles per hour to that travelling at 55 miles per hour (1mile = 1.61km)
3. Calculate the ratio of the time needed for the car to travel over a distance L at 55 mph to that at 90mph over the same distance L.
4. Calculate the ratio of the energy consumption for the car to travel over the distance L at 90 mph to that at 55 mph over the same distances L.
5. What conclusions can you draw from the above calculations from the viewpoint of fuel saving?