When you ride a bicycle at constant speed, nearly all the energy you expend goes into the work you do against the drag force of the air. Model a cyclist as having a cross-section area 0.45 m^2 and, because the human body is not aerodynamically shaped, a drag coefficient of 0.90.
(a) What is the cyclist's power output while riding at a steady 7.3 m/s (16 mph)?
(b) Metabolic power is the rate at which your body "burns" fuel to power your activities. For many activities, your body is roughly 25% efficient at converting the chemical energy of food into mechanical energy. What is the cyclist's metabolic power while cycling at 7.3 m/s?
(c) The food calorie is equivalent to 4190 J. How many calories does the cyclist burn if he rides over level ground at 7.3m/s for 1.5 hrs?