Explain why sweating cools you down in terms of molecular kinetic energy. You ta

Question

Explain why sweating cools you down in terms of molecular kinetic energy. You take a pizza out of the oven and let it cool briefly. When you bite into it. the crust is not too hot. but the cheese bums your mouth. Explain why this happens in terms of specific heat capacity. How much heat energy must you use to raise the temperature of 100 grams of water from 60degree C to 70degreeC? Show your calculations. You have a pot of 100degree C liquid water. If you add heat to the water, will the temperature start increase at once? Why or why not?

Explanation / Answer

39.  Beads of sweat on your skin are in liquid form. When the water temperature rises, the molecules become more active and gain energy. When a molecule gains enough energy, it can break free from the bonds that hold the liquid together and transform into water vapor. This is evaporation. As the molecule evaporates, its energy -- or heat -- is removed from the sweat that remains on your body. This loss of energy cools the surface of your skin.

40. when we take out pizza from oven its crust not that hot but cheese is too hot to handle becoz cheese has lot of water molecule which gets excited during baking process and remaining energy is used up to heat the crust (principle of microwave spectroscopy) , as a result crust cools down very fast but for cheese temperature to cool down it will take more time . that is why cheese burns your mouth.

41. we know the formula ,

Q= m s (T2 - T1) where Q= heat energy m = mass , S = specific heat T2 = final temp T1= initial temp

puting the values which are given we get ,

Q= 100 * 1* (70 - 60) [ specific heat of water is 1]

= 1000 J

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