A giant star radiates energy at the rate of 3.0 1030 W, and its ...

[nummyann]

A giant star radiates energy at the rate of 3.0  1030 W, and its surface temperature has been measured to be 3000 K. Assuming that it is a perfect emitter, what is the radius of this star? ( = 5.67  10-8 W/m2  K4)
 
  A) 7.8  1010 m
  B) 8.7  1010 m
  C) 1.4  1010 m
  D) 1.9  1011 m
  E) 2.3  1011 m

Question 2

The radius of a star is 6.95  108 m, and its rate of radiation has been measured to be 5.32  1026 W. Assuming that it is a perfect emitter, what is the temperature of the surface of this star? ( = 5.67  10-8 W/m2  K4)
 
  A) 6.27  103 K
  B) 8.25  103 K
  C) 8.87  103 K
  D) 3.93  107 K
  E) 5.78  107 K

[cat123]

Answer to Question 1

E

Answer to Question 2

A

[nummyann]

Excellent

[T4T]

Gracias!