After eating a 150 g bottle of yogurt, Bob decides to go for a run to burn off t

Question

After eating a 150 g bottle of yogurt, Bob decides to go for a run to burn off the
extra energy. The yogurt provides 4.4 MJ kg-1, and Bob is able to raise his metabolic rate
to 220 W while running. How long does he have to run?

I have two equations but i'm not sure which one to use:

delta U = (Q + E) - W

Where delta U is the change in E and

E  represents energy internalized

I also have

n=work done /  E used to do mech work

   =W / E * delta U

Please show work and solve. I'm not sure how I would represent time. Thank you!

Explanation / Answer

4.4 MJ/kg and we had 0.15 Kg, so we get 660,000 Joules

220 W = 220 J/s,

Energy/Power = time

660,000J/220J/s = 3000 s

3600 s = 1 hr

3000s/ 3600s/hr = 5/6 hr = 50 minutes

This seems about right; it isn't easy to lose weight.

Also food calories are 1000x bigger than physics calories.

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