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While running, a 62 kg student generates thermal energy at a rate of 1100 W . To

ID: 1529895 • Letter: W

Question

While running, a 62 kg student generates thermal energy at a rate of 1100 W . To maintain a constant body temperature of 34 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 a student run before irreversible body damage occurred? (Protein structures in the body are damaged irreversibly if the body temperature rises to 44 C or above. The specific heat capacity of a typical human body is 3480 J/(kgK), slightly less than that of water. The difference is due to the presence of protein, fat, and minerals, which have lower specific heats.)

Express your answer in seconds to two significant figures.

Answer: t = _______ s

Explanation / Answer

Mass of student: 62 kg

Rate the thermal energy is generated: 1100 W=1100 J/s

Time is t

Total energy (Q) is 1100t

delta(t) = 44 - 34 = 10 degree

Q = m*c*delta(t)

Q = (62 kg)*(3480 J/kgK)*(10 degree)

Q = 2157600J

Therefore,

1100t = 2157600J

t = 2157600J/1100J/s

t = 1961.45 sec.

t = 32.69 min.