How much perspiration must vaporize per hour to dissipate extra energy

In summary, the metabolism of basketball players can increase by 30.0 W during a game, leading to the need to dissipate extra thermal energy. To calculate the amount of perspiration required to vaporize this energy per hour, the thermal energy to be dissipated is calculated as 108 KJ/hr. Assuming perspiration is pure water, the required amount would be 4.78x10^-2kg, starting at a temperature of 37 degrees Celsius. The use of 37 degrees is necessary when determining the value of ∆Hvap for water, as it is not a fixed value across all temperatures.
  • #1
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Homework Statement



During the game, the metabolism of basketball players often increases by as much as 30.0 W. How much perspiration must a player vaporize per hour to dissipate this extra thermal energy? Assume that perspiration is simply pure water and that perspiration starts at temperature of 37 degrees celcius.

Homework Equations



Q=mcΔT
Q=mHv

The Attempt at a Solution



Thermal energy to be dissipated in 1.00h is
U=(30J/s)(3600s/hr)=108KJ/hr

The amount of water this energy transmittes as heat would vaporize is,
m=(1.08x10^5J)/(2.26X10^6J/kg)= 4.78x10^-2kg

I'm not sure if I'm doing it correctly. I never used 37 degrees/
 
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  • #2
Jtwa said:
I'm not sure if I'm doing it correctly. I never used 37 degrees/
Did you have body temperatures in previous problems? Maybe the players start at lower temperatures?
 
  • #3
Jtwa said:
The amount of water this energy transmittes as heat would vaporize is,
m=(1.08x10^5J)/(2.26X10^6J/kg)= 4.78x10^-2kg

I'm not sure if I'm doing it correctly. I never used 37 degrees/
You use 37° when reading from tables to determine what value of ∆Hvap to use because it is not a fixed value across all temperatures, ∆Hvap falls slightly as temperature rises. http://www.thermexcel.com/english/tables/vap_eau.htm
 

1. How is perspiration related to dissipating extra energy?

Perspiration, or sweat, is the main mechanism by which our bodies dissipate extra energy. As sweat evaporates from our skin, it carries away excess heat, helping to cool our bodies down.

2. How much perspiration must vaporize per hour to effectively dissipate extra energy?

The amount of perspiration that must vaporize per hour to effectively dissipate extra energy varies depending on factors such as the individual's level of physical activity, ambient temperature, and humidity. However, on average, the human body can produce about 1 liter of sweat per hour.

3. Can excessive perspiration lead to dehydration?

Yes, excessive perspiration can lead to dehydration if the lost fluids and electrolytes are not replenished. It is important to drink plenty of water and electrolyte-rich fluids during physical activity to prevent dehydration.

4. Does the rate of perspiration vary among individuals?

Yes, the rate of perspiration can vary among individuals based on factors such as age, gender, fitness level, and genetics. Some people may naturally produce more sweat than others, and some may also have a higher sweat rate during physical activity.

5. How does the body regulate perspiration to dissipate extra energy?

The body regulates perspiration through the sympathetic nervous system, which triggers sweat glands to produce sweat in response to increased body temperature. The amount of sweat produced is also influenced by factors such as hormones, hydration levels, and external temperature.

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