Homework Help: Physics HELP!!!!!!!!

Posted by Mary on Wednesday, April 18, 2007 at 11:16pm.

In exercising, a weight lifter loses 0.100 kg of water through evaporation, the heat required to evaporate the water coming from the weight lifter's body. The work done in lifting weights is 1.30 x 10^5 J.

(a) Assuming that the latent heat of vaporization of perspiration is 2.42 x 10^6 J/kg, find the change in the internal energy of the weight lifter.

(b) Determine the minimum number of nutritional calories of food (1 nutritional calorie = 4186 J) that must be consumed to replace the loss of internal energy.

It would be better if you could post your answer first so that we can help. This is not a forum to do the homework for you.

If mass of water lost =m and latent heat =L
then energy used to evaporate water is mL

If work done in lifting weights is W then the total energy used is mL+W

Assuming that this is the energy that needs to be replaced then the number of calories is (mL+W)/4186

If you want to post your calculations we can check these.

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