A 66 kg woman cheats on her diet and eats a 643 Calorie (540 kcal) jelly donut for breakfast.
a) How many joules of energy are the equivalents of one jelly doughnut?
b) How many stairs should the woman climb to perform an amount of mechanical work equivalent to the food energy in one jelly doughnut? Suppose the height of a single stair is 15 cm.
c) If the human body is only 30% efficient in converting chemical energy to mechanical energy, how many stairs should the woman climb to work off her breakfast?