- #1
Hausdorff
- 2
- 0
Hi!
I am trying to understand the statistical mechanics derivation of the ideal gas law shown at: http://en.wikipedia.org/wiki/Ideal_gas_law inder "Derivations".
First of all, the statement "Then the time average momentum of the particle is:
[itex] \langle \mathbf{q} \cdot \mathbf{F} \rangle= ... =-3k_BT.[/itex]". Isn't this wrong? For sure, the dimension of [itex] \langle \mathbf{q} \cdot \mathbf{F} [/itex] is energy, as is the dimension of [itex]-3k_BT[/itex] and not momentum.
Secondly, I do not understand the equation
[itex] -\langle \sum_{i=1}^{N}\mathbf{q}_k \cdot \mathbf{F}_k \rangle = P \oint_{\mathrm{surface}} \mathbf{q} \cdot d\mathbf{S} [/itex].
I dot not understand what [itex]\mathbf{q} [/itex] is, since all position vectors have been subsricpted. Nor do I understand the physical interpretation of [itex] \mathbf{q} \cdot d\mathbf{S}[/itex]: the scalar product of [itex] \mathbf{q} [/itex] (a position vector?) and the vector area element.
If anybody could shed some light on this, I would be very grateful.
I am trying to understand the statistical mechanics derivation of the ideal gas law shown at: http://en.wikipedia.org/wiki/Ideal_gas_law inder "Derivations".
First of all, the statement "Then the time average momentum of the particle is:
[itex] \langle \mathbf{q} \cdot \mathbf{F} \rangle= ... =-3k_BT.[/itex]". Isn't this wrong? For sure, the dimension of [itex] \langle \mathbf{q} \cdot \mathbf{F} [/itex] is energy, as is the dimension of [itex]-3k_BT[/itex] and not momentum.
Secondly, I do not understand the equation
[itex] -\langle \sum_{i=1}^{N}\mathbf{q}_k \cdot \mathbf{F}_k \rangle = P \oint_{\mathrm{surface}} \mathbf{q} \cdot d\mathbf{S} [/itex].
I dot not understand what [itex]\mathbf{q} [/itex] is, since all position vectors have been subsricpted. Nor do I understand the physical interpretation of [itex] \mathbf{q} \cdot d\mathbf{S}[/itex]: the scalar product of [itex] \mathbf{q} [/itex] (a position vector?) and the vector area element.
If anybody could shed some light on this, I would be very grateful.