# Homework Help: Thermodynamics: Air pressure at 3000m above sea level

Tags:
1. May 18, 2015

### mikeclinton

Hello all! Can you please provide some guidance with this problem?

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

Calculate the air pressure at 3000m above sea level assuming that the molecular weight of air is 29 and the ambient temperature is constant against height.
2. Relevant equations
Stokes-Einstein equation. In fact, brownian motion was the focus of the class but I fail to understand how it can be applied to the problem above.

Thank you! Any help is much appreciated!

2. May 18, 2015

### Staff: Mentor

Have you studied hydrostatics yet? In terms of density, what is the derivative of pressure with respect to elevation?

Chet

3. May 18, 2015

### mikeclinton

Hello Chet, thank you for your reply! I have in fact managed to solve the problem using the barometric formula (if my calculations are correct P=533.04 with sea level atmospheric pressure set at 100kPa). However, our teacher instructed us to utilize Brownian motion theory; I'm not too familiar with it and thus can't see how it is relevant here.

4. May 18, 2015