Another Question - Thermal Energy & Sweat this time

AI Thread Summary
To determine how much liquid is lost from the body when 630W is dissipated as thermal energy, it's essential to consider the heat of vaporization of sweat. The problem suggests that all dissipated heat is lost through sweat evaporation, requiring assumptions about the body's efficiency and metabolic rate. The lack of specific data, such as weight or temperature, complicates the calculation. Understanding the phase change involved in sweat evaporation is crucial for solving the problem. Ultimately, applying the heat of vaporization concept will help estimate the liquid loss from the body.
miava
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Homework Statement




If 630W is dissipated as thermal energy/heat how much liquid is lost from the body?


The Attempt at a Solution



I have got through a 3 part problem (re: energy, work etc) and found how much energy is dissipated as heat (630W), but I have no info that leads me to the answer to the last part - how much liquid is lost as sweat. I don't have information on weight, temp or anything else as it wasn't provided in the question.
The metabolic rate to 700W and the efficiency is 10% so 630W is left as heat.
 
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You'll have to make some assumptions, such as, all the heat that the body dissipates, it does so through the evaporation of sweat.

To make liquid sweat on your skin evaporate into vapor, it must under a change in phase. Something about heats of vaporization. Does this start to sound familiar with what you're doing in class?
 
Thread 'Variable mass system : water sprayed into a moving container'

Thread 'Variable mass system : water sprayed into a moving container'

Starting with the mass considerations #m(t)# is mass of water #M_{c}# mass of container and #M(t)# mass of total system $$M(t) = M_{C} + m(t)$$ $$\Rightarrow \frac{dM(t)}{dt} = \frac{dm(t)}{dt}$$ $$P_i = Mv + u \, dm$$ $$P_f = (M + dm)(v + dv)$$ $$\Delta P = M \, dv + (v - u) \, dm$$ $$F = \frac{dP}{dt} = M \frac{dv}{dt} + (v - u) \frac{dm}{dt}$$ $$F = u \frac{dm}{dt} = \rho A u^2$$ from conservation of momentum , the cannon recoils with the same force which it applies. $$\quad \frac{dm}{dt}...
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