Calculating Rate of Vaporisation: 240 W Body Heat Loss

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Homework Help Overview

The discussion revolves around calculating the rate of vaporization of sweat based on the heat loss from the body during exercise, specifically focusing on a heat loss of 240 W and a latent heat of 2255 kJ/kg.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • Participants explore the relationship between heat energy and mass using the latent heat formula, questioning how to derive a rate of vaporization from the given information. Some express uncertainty about the appropriate formulas and the conversion between units of energy and power.

Discussion Status

Participants are actively engaging with the problem, with some offering logical reasoning approaches while others seek clarification on the concepts involved. There is a mix of interpretations regarding the application of formulas and units, indicating a productive exploration of the topic.

Contextual Notes

There is a noted confusion regarding the distinction between watts and joules, as well as the conversion of energy to a rate of vaporization, which may affect the understanding of the problem setup.

roam
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Homework Statement



During exercise the body loses 240 W of heat due to the evaporation of sweat. Assuming that the latent heat of at body temprature is 2255 kJ/kg, determine the rate of vaporisation of sweat.

answer = 106 mg/s

Homework Equations



L=Q/m

The Attempt at a Solution



What formula do I need to use here? The only formula I can think of is the one with latent heat and heat energy Q=mL. But this formula only gives mass and doesn't give the rate of vaporisation!
 
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If 240J is added to the sweat per second and it takes 2255 000 J to vaporize one kg of sweat, how much is vaporized per second? You don't need any formulas, just logic.
 
ideasrule said:
If 240J is added to the sweat per second and it takes 2255 000 J to vaporize one kg of sweat, how much is vaporized per second? You don't need any formulas, just logic.

I'm not quite sure if I understand correctly, do you mean sweat+240J/2255000? :confused:
 
And it is 240 W not Joules...
 
roam said:
And it is 240 W not Joules...

a Watt is just a Joule per second.
 

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