Rate of heat radiated from a person

  • Thread starter Hendrick
  • Start date
  • Tags
    Heat Rate
In summary, the percentage increase in the rate of heat radiated from a person with a surface skin temperature of 34.0 °C compared with the same person with a skin temperature of 33 °C is approximately 1.31%. This is calculated using Stefan's Law of emission and taking into account the emissivity and surface area of the object.
  • #1
Hendrick
43
0

Homework Statement


What is the percentage increase in the rate of heat radiated from a person with a surface skin temperature of 34.0 °C compared with the same person with a skin temperature of 33 °C?


Homework Equations


Stefan's Law of emission:
P = σAeT^4

- P = rate of energy transfer (Watts)
- σ = 5.6696 x 10^–8 W m^–2 K^–4
- A = surface area of the object
- e = emissivity (varies from 0 to 1)
- T = temperature (Kelvins)

The Attempt at a Solution



(34+273)^4/(33+273)^4
= 1.013 % (3sf)

Actual answer is 1.31%
 
Physics news on Phys.org
  • #2
Hendrick said:
(34+273)^4/(33+273)^4
= 1.013 % (3sf)
That isn't a percentage, that's a ratio. You need to multiply by 100 to obtain a percentage.
 
  • #3
Hootenanny said:
That isn't a percentage, that's a ratio. You need to multiply by 100 to obtain a percentage.

Oh, thanks lol.


Is this right:-

(34+273)^4/(33+273)^4 * 100
= 101.3136113 %

the increase being:
= 101.3136113 % - 100
= 1.3136113%
 
  • #4
Looks good to me :approve:
 

1. How does the rate of heat radiated from a person vary?

The rate of heat radiated from a person varies based on several factors such as body size, activity level, and environmental conditions. Generally, larger individuals and those engaging in physical activity will radiate more heat than smaller or sedentary individuals.

2. What is the average rate of heat radiated from a person?

The average rate of heat radiated from a person is approximately 100 watts, which is equivalent to the energy needed to power a lightbulb. However, this can vary greatly depending on the factors mentioned above.

3. How does clothing affect the rate of heat radiated from a person?

Clothing can significantly impact the rate of heat radiated from a person. In general, more layers of clothing will trap more body heat, resulting in a lower rate of heat radiation. However, certain fabrics and materials, such as wool and synthetic fibers, can help regulate body temperature and allow for more efficient heat radiation.

4. Can the rate of heat radiated from a person be measured?

Yes, the rate of heat radiated from a person can be measured using a device called a calorimeter. This device measures the amount of heat energy produced by an object, including the heat radiated from a person's body.

5. How does age affect the rate of heat radiated from a person?

As we age, our bodies tend to produce less heat, resulting in a lower rate of heat radiation. This is due to a decrease in metabolic rate and a decrease in muscle mass. Additionally, older individuals may have a harder time regulating body temperature, which can also affect the rate of heat radiation.

Similar threads

  • Introductory Physics Homework Help
Replies
10
Views
2K
  • Introductory Physics Homework Help
Replies
1
Views
6K
  • Introductory Physics Homework Help
Replies
2
Views
1K
  • Introductory Physics Homework Help
Replies
1
Views
1K
  • Introductory Physics Homework Help
Replies
3
Views
1K
  • Introductory Physics Homework Help
Replies
12
Views
1K
  • Introductory Physics Homework Help
Replies
5
Views
2K
  • Introductory Physics Homework Help
Replies
8
Views
2K
  • Introductory Physics Homework Help
Replies
1
Views
905
  • Introductory Physics Homework Help
Replies
7
Views
2K
Back
Top