Recent content by LoopInt

I think you should look at symbolic algebra software in general, and the ones suggested are very good. My favorite is sympy, because of the Python integration and the community, but Reduce, wxMaxima, Sage, WolframAlpha, Mathematica, Mapple, Smath, Mathcad are the ones you should look. Consider...

While this is not a pure LaTeX editor, you might like the one I created. It can render with pdflatex and export to .tex. However, I made it to be simpler and faster to write than LaTeX, but to keep things beatiful like LaTeX typesetting. Some key advantages are Python and Sympy integration. You...

Thanks for the reply. I have a tank which is 4-8 bar connected to a pressure regulator at 2.5 bar. There is a pipe connecting the pressure regulator to the valve, and the valve to the chamber at atmospheric pressure, initially. So that means I can work with incompressible flow equations...

I was using p(0) as 0, because it was gauge pressure. I realized I should rather use the absolute pressure. Just out of curiosity: Will this be still valid for large delta P? I found the Hagen-Poiseuille equation, but it only works for low mach numbers, so maybe this one will too. If so, how...

That's very helpful, thanks! You said that the speed of sound can change, right? But looking at this equation: $$a = \sqrt{\gamma R T}$$ What changes when the pressure increases? $$R_{air}=287 \frac{J}{kg K}$$ $$\gamma_{air}=1.4$$ $$T= 300 K$$ (of the atmospheric temperature? Or do I need to...

I am confused about the relation of mass flow rate with different mach numbers in a compressible flow. In wikipedia (http://en.wikipedia.org/wiki/Choked_flow), I read the following: "Although the gas velocity reaches a maximum and becomes choked, the mass flow rate is not choked. The mass flow...

Ok, so I found that: p(t)=C1e^(-RTt/(MrV))+P p(0)=0 So, C1-P=0 ; C1=P p(t)=P(e^(-RTt)/(MrV)+1) And I will plot and estimate r from the data. But that M still Bugs me. I'm using the ideal gas law like this P=mRT/V where m is the mass in kg, R the air constant T temp and V volume. so I get...

Thanks! This is indeed the response I observed. However I have some further questions about this model. 1st: Differentiating both sides from the ideal gas gives: dp/dt=RT/V * dm/dt , so Whats the M you put in the equation and where it comes from? 2nd: How can I calculate the resistence "r"...

Sorry I took so long, \frac{T_2}{T_1}=\frac{(y-1)M}{ym} And I need to ask you something. I am trying to understand how viscoelastic materials behave. I'm getting hysteresis on my system and I think that it is mainly due to the latex rubber I'm using. I'm trying to model the dissipated energy...

Sorry, my head is somewhere else. T2=(((m+M)R+Cvm)T1)/(mR+Cvm)

Yea I left one m behind. So we have U2-U1=-W U2-U1=Cv(T2-T1) So, sunstituting the terms and solving for T2, I got T2= (nR(m+M)-Cvm)T1/(m(nR-Cv))

Ok. Let's check some concepts first. To calculate the entropy I need an expression of Q. To determine how Q changes we looked at the work that we calculated, because U2-U1=Q-W We know U2-U1 for the isothermal case, so we know that Q=W Now at the integration we have \int dQ/T We...

Why the minus sign? The work done by the system shouldn't be positive? (convention) Well, I don't know much of the first law. What I know is that dE = dQ - dW. So I will guess that, since E is the total energy of the system, we can ignore some terms of E. The kinetic energy of the system at...

Ok. First off, I have one question. It doesn`t matter if the system increases or decreases temperature in the middle, as far as Tinicial=Tfinal? Now to the problem. (m+M)g/A (V2-V1) At the initial state volume is V1 and we can use ideal gas law, because the system is at equilibrium. So...

I would like to start by the isothermal. If we can calculate the total energy too it would be better!