The fuel value of hamburger is approximately 3.3 kcal/g. If a man eats 0.75 pounds of hamburger for lunch and none of the energy is stored in his body, estimate the amount of water that would have to be lost in perspiration to keep his body temperature constant. The heat of vaporization of water may be taken as 2.41 kJ/g.

The mass of water lost to perspiration to maintain the temperature is 1.76 kg.

The given parameters;

The energy stored in the hamburger is calculated as follows;

454 g = 1 lb

4.186 kJ = 1 kcal

The mass of water lost to perspiration to maintain the temperature is calculated as follows;

where;

c is the specific heat capacity of water = 4.186 J/g⁰C

t₂ is the boiling point of water = 100⁰C

t₁ is normal body temperature = 37⁰C

Thus, the mass of water lost to perspiration to maintain the temperature is 1.76 kg.

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Explanation:

The energy stored in the hamburger is:

The amount of water perspired is derived from the following formula: