(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

Derive an equation for the change in entropy that occurs in an isolated (micro-canonical) system containing N particles, if an adiabatic expansion from volume V1 to volume V1 takes place. Show that the number of microstates is given by V^N.

2. Relevant equations

Entropy S = K[itex]_{b}[/itex] ln [itex]\Omega[/itex]

Where [itex]\Omega[/itex] is multiplicity, the number of microstates for distinguishable partciles= N!/[itex]\Pi[/itex][itex]_{i}[/itex]n[itex]_{j}[/itex]!

3. The attempt at a solution

Ok i'm not too sure where to start. I know that dQ = 0 as this is an adiabatic expansion.

Meaning dU = dW = - NK[itex]_{b}[/itex]T ln (V2/V1), but i'm not sure if this helps anything.

I also know that a microcanonical system is thermally isolated and has a fixed N. So would thermally isolated mean dT = 0? in which case dU = 0 ... confused.

please help!

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

Join Physics Forums Today!

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

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

# Homework Help: Change in entropy in an isolated system

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