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? asked in Science & MathematicsPhysics · 6 years ago

help please..i need the answer real quick..physics?

10. While running, a 70-kg student generates thermal energy at a rate of 1200 W. To maintain a constant body temperature of 37°C, this energy must be removed by perspiration or other mechanisms. If these mechanisms failed and the heat could not flow out of the student's body, for what amount of time could the student run before irreversible body damage occurred?

(Note: Protein structures in the body are irreversibly damaged if body temperature rises to 44°C or higher. The specific heat of a typical human body is 3480 J/kg • K, slightly less than that of water. The difference is due to the presence of protein, fat, and minerals, which have lower specific heats.)

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  • ?
    Lv 7
    6 years ago

    We will assume that, because the body mostly consists of water, the specific heat capacity is 4.2 kJ/(kg C).

    The amount of heat needed to raise the temperature of 70kg of water by 7 degrees is:

    Q = m C delta(T)

    = 70 kg * 4.2 kJ/(kg C) * 7C

    = 2058 kJ = 2.1*10^6 J

    Given the rate of heat production as 1200J/s, it will take a time

    t = Q/P = 2.1*10^6 J /( 1200 J/s) = 1715 seconds (28.5 minutes).

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