# Strange question

1. Sep 23, 2007

### Werg22

1. The problem statement, all variables and given/known data

Einstein's theory of general relativity is relativistic model of gravity. "Relativistic" means it involves the speed of light, c; "gravity" means it involves Newton's constant, G. Use dimensional analysis to derive a formula for the surface area, A, of a black hole of mass M, up to a dimensionless proportionality constant.

2. Relevant equations

N/A

3. The attempt at a solution

I have little idea of how to tackle this question. Any sort of help would be appreciable.

2. Sep 23, 2007

### Werg22

Can anyone be of help?

3. Sep 23, 2007

### Werg22

Bumping up again.

4. Sep 23, 2007

### Karma

werg lol phys 121 assignment 1 question 3 lol... hahaha waterloo university right?

5. Sep 23, 2007

### Karma

I couldn't do the last Problem... What did u get for (a) and (b)

6. Sep 23, 2007

### Proggle

As far as I can tell, the idea is to propose something along the lines of:

A= k*c^x*G^y*M^z

Where k is a dimensionless constant.

Then figure out what the exponents x,y and z must be so that the right hand has units of area (length^2). You should come up with a system of equations with only one solution.

7. Sep 24, 2007

### Werg22

I ended by figuring it out, thanks Proggle anyway. The question is kind of obscure and the solution isn't very intuitive.

Yes Karma I go to the University of Waterloo, I figured the same with you by your car race question.