How much water must be evaporated from the body of a human being to cool the bod | TestHub

Passage / Comprehension

Camels are knows as the ship of the desert. They require very little water because they can tolerate relatively large changes in their body temperatures. A camel permits its body temperature to drop to $3 4^{\circ} C$ overnight and rise to $4 0^{\circ} C$ during the day. In contrast, human beings keep their body temperature nearly constant. This they do by drinking water. The sweat thus formed evaporates and helps the body to maintain the body temperature. The specific heat capacity of a camel as well as of human being can be assumed to be $3500 J/kg K$ . Assume that the mass of the camel is $500 kg$ and mass of man is $50 kg$ .

How much water must be evaporated from the body of a human being to cool the body by $1^{\circ} C$ ?

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Answer:

Solution:

Heat lost by the body:
$Q_{l os t} = m s Δ T$
Heat gained by evaporating water:
$L_{v} = 540 cal/g$
$L_{v} = 540 \times 4.2 \times 1 0^{3} J/kg$
$Q_{g ain e d} = m^{'} L_{v}$
$50 \times 3500 \times 1 = m^{'} \times 540 \times 4.2 \times 1 0^{3}$
$m^{'} = \frac{5 \times 35}{540 \times 4.2}$
$m^{'} = \frac{25}{324} kg$

Physics - Heat & Thermo Question with Solution | TestHub

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