In this problem you will consider the balance of thermal energy radiated and absorbed by a person. assume that the person is wearing only a skimpy bathing suit of negligible area. as a rough approximation, the area of a human body may be considered to be that of the sides of a cylinder of length l=2.0m and circumference c=0.8m. for the stefan-boltzmann constant use σ=5.67×10−8w/m2/k4.if the surface temperature of the skin is taken to be tbody=30∘c, how much thermal power prb does the body described in the introduction radiate? take the emissivity to be e=0.6.express the power radiated into the room by the body numerically, rounded to the nearest 10 w.

Explanation:

According to the Stefan-Boltzmann law for real radiating bodies:

(1)

Where:

is the energy radiated (in Watts)

is the Stefan-Boltzmann's constant.  

is the Surface area of the body  

is the effective temperature of the body (its surface absolute temperature) in Kelvin

is the body's emissivity

On the other hand, we are told the human body is roughly approximated to a cylinder of length and circumference .

The circumference of a circle is: where is the radius. Hence .

Now we have to input this value for  in the Area of a cylinder formula:

(2)

Substituting (2) in (1):

(3)

Finally:

answer: the direction of the wind is expressed as the direction from which the wind is blowing. for example, easterly winds blow from east to west, while westerly winds blow from west to east.

explanation: