The problem set can be found here: http://www.physics.utoronto.ca/%7Epoppitz/hw1.pdf [Broken] I am mainly having a problem with question II Part 2.(adsbygoogle = window.adsbygoogle || []).push({});

Here's what I have so far:

II) 1. Since the probability that a given molecule is in a subvolume [tex]V[/tex] is [tex]\frac{V}{V_0}[/tex]. It follows that the mean number of molecules is proportional to this ratio as well.

[tex]\frac{<N>}{N_0} = \frac{V}{V_0}[/tex]

[tex]<N> = \frac{V N_0}{V_0}[/tex]

2.

[tex]<(N-<N>)^2> = <N^2 - 2 N <N> + <N>^2[/tex]

[tex]<(N-<N>)^2> = <N^2> - 2 <N>^2 + <N>^2[/tex]

[tex]<(N-<N>)^2> = <N^2> - <N>^2[/tex]

[tex]\frac{\sqrt{<(N-<N>)^2>}}{<N>} = \frac{\sqrt{<N^2> - <N>^2}}{<N>}[/tex]

Now from here I can substitute into the regular [tex]<N>[/tex] terms but I don't know how I'm supposed to find [tex]<N^2>[/tex]?? Any help would be greatly appreciated.. thanks!

**Physics Forums | Science Articles, Homework Help, Discussion**

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Homework Help: Thermal/Statistical Physics Problem

**Physics Forums | Science Articles, Homework Help, Discussion**