1. Apr 18, 2007

### Yarka

Physics

If a star has a surface temperature of 1000 degrees Kelvin and emits 500,000 watts of each square-meter of surface area, how much power does each square-meter of its surface area emit after it has cooled to 900 degrees Kelvin?

2. Apr 18, 2007

### Hootenanny

Staff Emeritus
Welcome to the Forums,

Have you any thoughts on the question? Which law do you think we should use?

3. Apr 18, 2007

### Yarka

If a star has a surface temperature of 1000 degrees Kelvin and emits 500,000 watts of each square-meter of surface area, how much power does each square-meter of its surface area emit after it has cooled to 900 degrees Kelvin?

4. Apr 18, 2007

### Yarka

Stephen-Boltzmann's Law i guess, but i couldn't figure out how? plz help if u have any idea

5. Apr 18, 2007

### Hootenanny

Staff Emeritus
Well you could start by writing down the Stephen-Boltzmann law and identifying what all the symbols mean...

6. Apr 18, 2007

### Hootenanny

Staff Emeritus

7. Apr 18, 2007

### Yarka

Thanks, am a kind of confused.

8. Apr 18, 2007

### Yarka

it may be easy for u to answer, so plz help me?

9. Apr 18, 2007

### Hootenanny

Staff Emeritus
I am trying to help you. The guidelines here at PF prevent us from providing solutions to problems, they also require that you show your efforts and that we guide you through the problem rather than just handing you the solution on a plate.

10. Apr 18, 2007

### Yarka

ok. this is what i have= v/t=pi*P*D^4/128*L*Visc.

so 500,000=3.14*100*1000/128*L
Am i right?

11. Apr 18, 2007

### ZapperZ

Staff Emeritus
Two different threads have been merged because the OP made multiple postings.

Zz.