Jason, a 60 kg cyclist, is pedaling his bike at a good clip, using a total energ

Question

Jason, a 60 kg cyclist, is pedaling his bike at a good clip, using a total energy of 400 W. As he exercises, his body will start to warm up, and he will perspire to keep himself cool.

1) Assuming Jason’s pedaling has a typical 25% efficiency, by how much would his body temperature rise during 1.0 h of cycling if he had no means of exhausting excess thermal energy?

2) Assume that the only means by which his body cools itself is evaporation. To keep his body temperature constant, what mass of water must be evaporated during a 1.0 h ride? What volume of water must he drink each hour to keep from becoming dehydrated? (1.0 kg of water has a volume of 1.0 L.)

Explanation / Answer

SINCE HE HAS 25 PERCENT efficiency so he must be generating 400/4 = 100oules/sec

so in one hour , he has to generate, 100 . 3600 = 360kJ

SO CONSIDERING maximum part of body as water.

360000 = mass * sp heat * (change in temp )

rise in temp =1.43 degrees

b) to absorb 360kJ OF HEAT mass of water to be evaporated = mL

SO MASS = 360kJ/540 * 103

= 0.67 kg of water

Related Questions

Navigate

• Browse (All)
• Browse J
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.