Maximum power question

Question

A 200 g bag of potato chips contains 4.8 MJ of energy. How long would it take you working at your maximum power to consume this energy? Give your final answer in hours, minutes and seconds. (For example: 1 hour 34 minutes and 23.7 seconds). Show your work

Answer 1

First, let us get the energy into SI units.

4.8 MJ = 4,800,000 J

The maximum power part is confusing, but looking up the average maximum power of a human it is around 2000 Watts.

Now a watt is 1 Joule per Second, so our power (P) must be equal to the amount of energy total (E) over the time needed or

P=E/t

Using algebra,

t= E/P = (4,800,800 J) / (2000 J/s) = 2400 s <--- Look how the units worked out!

This answer simplifies to 40 minutes