Thermal energy to be dissipated in an hour

In summary, the metabolism of basketball players can increase by 30.0 W during a game. To dissipate this extra thermal energy, a player would need to vaporize approximately 4.78x10^-2kg of pure water per hour, assuming a starting temperature of 37 degrees celcius. However, the heat of vaporization for water varies with temperature, so this calculation may not be entirely accurate. It is recommended to double check the reasoning and calculations, as well as consider the number of significant figures used.
  • #1
dani123
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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/h)=1.08x10^5J

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

----> Just looking for someone to double check my reasoning/calculations and to make sure the number of significant figures has been respected. Thank you so much in advance!
 
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  • #2
You don't seem to have taken into account the starting temperature of the perspiration.
 
  • #3
your calculation for the energy needed to vaporize that amount of water is correct.
 
  • #4
Hmm. The heat of vaporization for water varies with temperature. At the boiling point (100C) it's 2.257 x 106 J/kg, but at 37C it's more like 2.40 x 106 J/kg.
 
  • #5


Your reasoning and calculations seem correct. However, the number of significant figures should be rounded to 3, since the given values have 3 significant figures. Therefore, the final answer should be 4.78x10^-2 kg.
 

What is thermal energy to be dissipated in an hour?

Thermal energy to be dissipated in an hour refers to the amount of heat that needs to be removed from a system or object within an hour in order to maintain a certain temperature.

Why is it important to dissipate thermal energy?

Dissipating thermal energy is important because it helps to prevent overheating and damage to systems or objects. It also helps to maintain a safe and comfortable environment for humans and other living organisms.

How is thermal energy dissipated?

Thermal energy can be dissipated through various methods such as convection, conduction, and radiation. Convection involves the transfer of heat through a fluid, conduction involves direct contact between objects, and radiation involves the emission of heat through electromagnetic waves.

What factors affect the amount of thermal energy to be dissipated in an hour?

The amount of thermal energy to be dissipated in an hour can be affected by factors such as the initial temperature of the system or object, the rate of heat generation, and the efficiency of the dissipating method being used.

How can the dissipation of thermal energy be increased?

The dissipation of thermal energy can be increased by improving the efficiency of the dissipating method, increasing the surface area of the object or system, and reducing the temperature difference between the object and its surroundings.

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