If a runners power is 400 watts as she runs, how much chemical energy does she convert into other forms in 10 minutes

Energy converted =

Explanation:

Recall that Power is the rate at which energy is transferred therefore defined by the mathematical formula:

Since the information on the power of the runner is given, as well as the time the energy conversion takes place, we can then use this equation to find how much energy is been converted. Notice that we just need to change the given time *10 minutes) into the appropriate units  (seconds)to get the answer in SI units of energy (Joules). The conversion of 10 minutes into seconds is done by multiplying : 10 minutes * 60 seconds/minute = 600 seconds.

We use this then to find the energy converted by the runner:

because if the tool that you are using is not balanced it there would be false mass.