Question

A 100 kg student eats a 200 Calorie doughnut. To "burn it off," he decides to climb the steps of a tall building. How high would he have to climb to expend an equivalent amount of work?

Answer 1

Answer: 853.88m

Explanation:

The 200 calorie donut is really 200 kilocalories or 200000 calories. Each calorie is 4.184 Joules. Therefore, the amount of energy the donut gives the student is 836800 Joules. In order to find the height (displacement) the student would have to climb, use W=Fd or work = force*displacement. We know the work and we can find the force easily with mg. 100kg*9.8m/s^2 = 980N. d = W/F. Therefore, d = 836800J/980N, or 853.88m.