Question

PLEASE HELP!!!! NEED ANSWER!!! I only have 15 minutes!!! Star X has a surface temperature of 10,000 K. How much power does it emit per square meter? Enter numbers only. Do not enter units (watt/m2 is assumed).

Answer 1

Do you know the radius of the star?

Answer 2

It does not say. That is the question… as is. Help!!

Answer 3

(Cosmic calculations and the doppler shift). I cannot figure it out for the LIFE of me!!

Answer 4

Ok, you can assume the start is a perfect blackbody radiator, and use Stefan-Boltzmann equation.

Answer 5

The Stefan-Boltzmann constant is
\[\large 5.67 \times 10^{-8} \frac{W}{m^2K^4}\]

Answer 6

Whenever you are doing physics, always think in terms of the units of measurement.

Answer 7

You want an answer in terms of W/m^2.
The constant I provided is in terms of W/(m^2 K^4)
So if you multiply by a temperature (in K)^4, the units of K^4 will cancel leaving only the units that you want.
It is no different than converting from miles-per-hour to meters-per-second.

Answer 8

So, you can't multiply 5.67 × 10^-8 by 10,000^4 ?