Suppose working outside on a hot day someone generate 450 J of heat each second.If this energy is compensated for by the evaporation of sweat,how much water would be lost in an hour? The latent heat of fusion for water is 334 kJ/kg and for vaporization is 2,200 kJ/kg.
A) 4.85 liter
B) 0.74 liter
C) 0.50 liter
D) 1.5 liter

Question

Quizplus · Accepted Answer

First, we need to find out how much energy is produced in an hour:
450 J/s x 60 s/min x 60 min/hr = 1,620,000 J/hr

We know that all of this energy is being used to evaporate sweat. The amount of water that needs to be evaporated can be calculated using the formula:

ΔHv = m x Lv

where:
ΔHv = heat of vaporization = 2,200 kJ/kg
Lv = latent heat of vaporization for water
m = mass of water

Solving for m:

m = ΔHv / Lv

m = 2,200,000 J / 2,200,000 J/kg

m = 1 kg

This means that for every kg of water that evaporates, 2,200,000 J of energy is absorbed. So, to absorb 1,620,000 J of energy, the mass of water that needs to evaporate can be calculated as:

1,620,000 J / 2,200,000 J/kg = 0.74 kg or 0.74 L

Therefore, the amount of water lost in an hour is 0.74 L, which is answer choice B.

Suppose Working Outside on a Hot Day Someone Generate 450