Recent content by Hobold

Octave is a free open-source alternative to MATLAB that does virtually everything MATLAB does, except possibly for some packages such as Simulink and some optimization tools, but they are always implementing more functions. The programming language is the same, too. However, if you are new to...

Because the air out of the car is at a higher velocity in reference to the window than the inner air, by Bernoulli's principle, the pressure outside must be lower, therefore you have a pressure force acting on the paper and thus it is "sucked" to ouside.

That is how Cv is defined. Cv is the limit when ∆T goes to zero of ∆u/∆T. The first statement is simply a consequence of internal energy being dependent only of T for an ideal gas.

Still there is a lot to take in account. For space, let's see: the player will lose heat to space mainly by radiation. We would have to simplify this a lot, such as: considering a human being is made of around 70% water, let's make it a round ball of water. Also, this ball of water is in...

Hello! Heat transfer is a though thing. This heat process you describe is very complex and if you want to make it realistic you must acknowledge you are going into a bunch of physics. Heat transfer is mainly governed by three physical phenomena: convection, radiation and conduction. It really...

m, kg and s are the units this constant is written in (meters, kilograms and seconds respectively). The constant is read as 6.67384 times 10 to the power of -11 cubic meters per kilogram second squared.

Reversibility is a tricky concept. A quasi-static process may not be reversible, but a reversible process must be quasi-static because you must be able to track every previous state you had to access in order to get to the desired one. A process is reversible if you can control the heat your...

You can, although liquids in general are not very sensitive to pressure, that is, their volumes and other thermodynamic properties do not greatly change with pressure, only with temperature. Same for solids. The pressure, however, changes greatly. If you apply a pressure of 500 times the...

As they said, you can't consider there isn't heat exchange because in order to maintain the same temperature, you must exchange heat. Also, internal energy is a function of temperature only if we are talking about ideal gases. This property does not hold for real gases.

The intensity is inversely proportional to the radius squared. That is, if a certain source has a power P and it emits pressure waves spherically, the intensity I you'll hear is I = \frac{P}{4\pi r^2}

Yes, everything changes and that's why you use a differential equation to solve this problem. You will have to work with three equations: 1) Differential form of Bernoulli's 2) Rate of change of mass 3) Ideal gas law Can you find a equation for velocity using 1) and 3)? Tip: make a few...

I'm sorry, that's wrong of course, must've been my distraction. It should be \frac{dm}{dt} = V\frac{d\rho}{dt} = \rho A v

I don't think you can use Bernoulli's equation to solve, as most requirements are not met (dm/dt is not constant, air is not incompressible. You may use its differential form, though: \frac{dp}{\rho} + d(\frac{v^2}{2}) + g dz = 0 Now you'll have to make a few hypothesis, such as the processes...

Hey people! I am interested in building a small cluster. At this lab I work for, we have a bunch of Pentium IV 1GB RAM computers we no longer use. To retain them from uselessness, we are thinking of the possibility of building a small cluster. I have read a few guides, but most are over 10...

Thanks! I don't really plan to learn much more English in such a short period, I want to familiarize with the test and focus on what's asked on TOEFL.