explain The surface of the Sun has a temperature of about 5 800 K. the radius of

Question

explain

The surface of the Sun has a temperature of about 5 800 K. the radius of the Sun is 0.96 Times 10^8 m. Calculate the total energy radiated by the Sun each second. Assume that the emissivity of the Sun is 0.986. A student is trying to decide what to wear. His bedroom is at 17.0 degree C. His skin temperature is 35.0 degree C. The area of his exposed skin is 1.45 m^2. People all over the would have skin that is dark in the infrared, with emissivity about 0.903. Find the net energy loss from his body by radiation in 10.2 min.

Explanation / Answer

1) The Stefan-Boltzmann constant = (2*5*k4)/(15*c2*h3)
=5.6704E-8 J/(s*m2*K4)

P=AT4

=5.6704E-8*0.986*(4*(6.96E8)2)*58004

P=3.85E26 W

2) T1 = 17 + 273 = 290 K

T2 = 35 + 273 = 308 K

e = 0.903

A = 1.45 m2

t = 10.2 x 60 = 612 s

= 5.67 x 10-8 W/m2K4

Q/t = eA(T24 - T14)

Q = (612s)(0.903)(1.45 m2)(5.67 x 10-8 W/m2K4)((308 K)4 - (290 K)4)

= 87524.49 J

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