# Homework Help: What's the nature of a force acting on this gas? (Thermo)

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1. Feb 21, 2016

### Raynor49

1. The problem statement, all variables and given/known data
A gas in equilibrium has distribution function:
f(p,r) = C0*(1+y*x)(2*pi*m*k*T)-3/2*exp(-p2/(2*m*k*T))
where x is the distance along an axis with fixed origin, and y is a constant.
What's the nature of the force acting on this gas?
2. Relevant equations
Maxwell bolztmann distribution for the momentum vector:

f(p) = (2*pi*m*k*T)-3/2*exp(-p2/(2*m*k*T))

3. The attempt at a solution
I'm honestly not even sure what this question is asking. What does it mean by the "nature" of the force acting on the gas? I had initially thought this question was asking for like a qualitative description of what type of force could be acting on the gas, but I have the solution to this problem which goes:

There is an effective temperature-dependent potential U(x) given through exp(-U/(k*T) ) = C0*(1+y*x)

and I fail to see how that explains the nature of the force acting on the gas, so I think I must be not understanding what this question is looking for. Any ideas or tips would be greatly appreciated!

Thanks!

2. Feb 23, 2016

### Simon Bridge

You should check your immediate coursework for clues ... the detail suggests they want a mathematical description of the force field that produces such a distribution as a starting point. After that, how you are supposed to describe the "nature" of the force should become apparent. i.e. is it an inverse-square force? Then it would be exerted by a point or spherical source. It may be conservative or non-conservative ... all sorts of ways.