Calculating Body Heat Loss and Caloric Needs: A Homework Guide

But if you can find a formula for deltaL, then you should be able to find the spacing.In summary, the average human body has a surface temperature of 30 degrees Celsius, a skin surface of 1.20m, and an emissivity of 1.0. If the surrounding temperature is 20 degrees Celsius, the body's net rate of heat loss due to radiation is 0 Watts. To maintain this body temperature, only radiative heat losses must be considered, and the number of food calories that must be consumed per day is unknown. Additionally, for a segment of 12m-long steel rails that are laid end to end when the temperature is -12 degrees Celsius, the spacing between them when the temperature
  • #1
Jenn_Lane2001
The average human body has a surface tempreture of 30 degrees Celsius, a skin surface of 1.20m and an emissivity of 1.0.

A. If the surrrounding tempreture is 20 degress Celsuis, the body's net rate of heat loss due to radiation is ________ Watts.

B. How many food calories must be consumed per day to maintain that body tempreture if only radiative heat lossess are considered?________.

Thanks for the help.
 
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  • #2
Hi Jenn, and welcome to PF.

We are happy to help you with your homework, but we need to see that you have attempted it first. Show us how you started and where you got stuck, and we will assist you through the rough spots. I think you will find that this problem is a straightforward "plug-and-chug" when you locate the formula in your book.

Thanks,
 
  • #3
Thank you for the reply here goes ...

Well I had a problem finding a forumla for this but I came up with .. P = sigma*A*e[T^4-T0^4]..I was give the tempretures and Area and emissivity. I am not sure if I was able to just plug it in or if I am using the right equation. It might be simple but since I wasnt given a book to solve this I am a little stuck..This was extra credit,to see if we can solve with research. Thank you for the help in advance.
 
  • #4
Also did I do this other problem correct..?

Segement of 12m-long steel rails are laid end to end when the tempreture is -12 degrees Celsius. A space is left between rails segments to allow for thermal expansion.
A.If they are to just touch when the tempreture is 33 degrees Celsisu the spacing is..____________.
My answer is 5.94*10^-3

I used deltaL = [(11*10^-6)(12)][45]=.00594

Thanks for the help everyone.
 
  • #5


Originally posted by Jenn_Lane2001
Well I had a problem finding a forumla for this but I came up with .. P = sigma*A*e[T^4-T0^4]..I was give the tempretures and Area and emissivity. I am not sure if I was able to just plug it in or if I am using the right equation.


Well, if the symbols take on their usual meaning (check this!), then...

P=power
sigma=Stefan-Bolzmann constant
A=area
e=emissivity
T,T0=temps

then you have the right equation.
 
  • #6


Originally posted by Jenn_Lane2001
I used deltaL = [(11*10^-6)(12)][45]=.00594

Since I do not know where all those numbers came from, I cannot say.
 

1. What is body heat loss and why is it important to calculate?

Body heat loss refers to the loss of heat from the body to the surrounding environment. It is important to calculate because maintaining a stable body temperature is crucial for our health and well-being. If our body loses too much heat, we can experience hypothermia, while retaining too much heat can lead to hyperthermia.

2. How do you calculate body heat loss?

Body heat loss can be calculated using the formula Q = m x c x deltaT, where Q is the amount of heat lost, m is the body's mass, c is the specific heat capacity of the body, and deltaT is the change in temperature. This formula takes into account factors such as body size, body composition, and the temperature difference between the body and the environment.

3. What factors affect body heat loss?

Several factors can affect body heat loss, including environmental temperature, wind speed, humidity, clothing, and physical activity. A colder temperature, higher wind speed, lower humidity, and less clothing can all increase body heat loss, while physical activity can generate more heat and decrease heat loss.

4. How can I calculate my daily caloric needs?

To calculate your daily caloric needs, you can use the Harris-Benedict equation, which takes into account your age, gender, weight, and activity level. This equation estimates the number of calories you need to maintain your current weight. However, it's important to note that this is just an estimate and individual needs may vary based on factors such as metabolism and genetics.

5. How do I use the information from calculating body heat loss and caloric needs?

Knowing your body's heat loss and caloric needs can help you make informed decisions about how to dress appropriately for the weather and how much food to consume to maintain a healthy weight. It can also be useful for outdoor enthusiasts and athletes who may need to take extra precautions to prevent heat-related illnesses or ensure they are properly fueling their bodies for physical activity.

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