Question

Your fitness tracker tells you that you have delivered 124 kJ of work during your workout. The tracker also shows that you have burned 124 food calories. How much energy (in kJ) has your body lost to the surroundings in the form of heat? Give your answer to two significant figures. Make sure to include the appropriate sign.

Answer 1

To solve this problem, we must basically count the total energy lost converting all the values given in the international system.

The energy loss is given by both 124KJ and 124food heats.

Since the energy conversion we know that 1 food calories is equal to 4,184J. So:

$124 calories (\frac{4.184J}{1 calories}) = 518.816J = 0.518816kJ$

Therefore the total energy lost will be

$E_{lost} = 124 KJ + 0.518816 KJ$

$E_{lost} = 124.518KJ$

Therefore the total energy lost to the surroindings in form of heat is 124.518kJ