A 61, 8-kg runner produces 329 J of energy per second while running a marathon.

Question

A 61, 8-kg runner produces 329 J of energy per second while running a marathon. Assuming 11.3% of the energy is delivered to the muscle tissue and that the excess energy is removed from the body by evaporation of sweat, determine the mass of fluid (assume it is water) lost per hour. At 37 degree C, the latent heat of vaporization of w is 2.41 times 10^6 J/kg. Note that the sweat is not boiling. Water will vaporize at any temperature. For example, water will evaporate (vaporize) off of the top of a table room temperature. The latent heat of vaporization is different at different temperature That's why we give its value in this problem. Here, the sweat is vaporizing at 37 degree C. temperature of the body. You don't need to calculate the heat required to raise the temperature of the sweat to 37 degree C. The sweat is already at that temperature. g (plusminus 2 g)

Explanation / Answer

Energy coming out in the form of sweat=100-11.3=88.7 percent=0.887*329=291.8 J

Let the mass is m kg

m*2.41*10(6)=291.8

We got m=1.21*10(-4) kg or 0.121 g lost in 1 sec

Lost in one hour=0.435 kg or 435.92 g

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