# Maxwell speed distribution

1. May 16, 2012

### b.hessen

halo, I´m stuck in an definite integral...

P(v)=4π (M2πRT)3/2⋅v2⋅e−Mv2nRT (maxwell speed distribution)

How can I calculate the fraction of Ar in mars?

pd. I got already the scape velocity

But... How can I intregrate and evaluate between (0, 5XE3 m/s) or (5XE3 m/s, infinite) ??

Is there any tables for evaluate this??

thanks

2. May 17, 2012

### clamtrox

You can at least find tabulated values for the error function, erf(x) = 0x dx' exp(-x'^2). It might be easier just to plug in the numbers and integrate numerically, for example by using wolfram alpha.

3. May 17, 2012

### b.hessen

thanks...
I calculated in Origin 8.5 (five minutes) trapezoids area... 50 000 intervals... It work as well and "rough" solution, good for giving a fast solution.