(a) How much work does a major-league pitcher do on the baseball when he throws a 90.0 mi/h (40.2 m/s) fastball? The mass of a baseball is 153 g.
(b) How many fastballs would a pitcher have to throw to "burn off" a 1520-Calorie meal? (1 Calorie = 1000 cal = 1 kcal.)
Assume that 80.0% of the chemical energy in the food is converted to thermal energy and only 20.0% becomes the kinetic energy of the fastballs.