Recent content by bbbeard

No, it's 1/3. See attached.

The shuttle flew most of the in-atmosphere reentry profile at a 40 degree angle-of-attack. This orientation intentionally generates a huge amount of drag, especially in the transonic regime. I don't think your observation has any bearing on the transonic human question.

Sort of. If you have an energy expressed in electron volts, and you know the charge, you get a voltage (a potential difference) when you divide the energy by the charge. Charges are not always equal to the elementary electron charge. For example, an alpha particle is like a helium nucleus, so it...

For a tube open at both ends, the pressure is equal to atmospheric at both ends. It oscillates inside the tube when excited at the appropriate frequency. The lowest mode will see the maximum pressure oscillations at mid-length (this is called a pressure antinode). So the lowest-mode...

Well, if I were to make this plot, I would use R. It could do everything on the plot fairly easily, with the exception of the spring in the dumbbell. I would do that in a drawing program, and take a screen shot and embed it in the R plot.

I get sqrt(117E9 Pa / 8.94E3 kg/m3)/(3.1416*0.01143 m) = 100.75 kHz. This seems really high to me. I suppose the diameter is pretty small. But how big would a copper ring have to be to produce, say, a 100 Hz (not kHz) tone? This calculation suggests you get there only when the diameter...

Yes, and you were right. It's just that the OP is still confused about the "error in [the] book". The OP wrote in the most recent post: which suggests ongoing confusion And as you and I both suspect, the "error" is not in the book at all, but was an error of transcription. BBB

I can't vouch for technician's approach, though I endorse much of what Studiot has written. The way I always keep this straight is to make sure I call "f" the "cyclic frequency" and ω the "angular frequency". Both have literal dimensions of T-1, but have different units. I usually just denote...

Well, it's a complicated ducting arrangement, but my first estimate would be based on assuming (a) the flow area at "A" is about the same as that of the throat, (b) that the flow at A is about 60 degrees offset from the flow at the throat, and (c) that the backpressure at B is not sufficient to...

The thing you have to realize is that pumping and throttling are two very different processes. In a pump you put in shaft power and raise the enthalpy of the fluid -- ideally in a reversible way, or nearly reversible way, so that very little entropy is generated and the temperature rises only a...

"d" is the diameter. The breathing frequency is independent of the length of the ring. Of course, a finite length tube will have longitudinal modes as well as radial modes. BBB

The amount of temperature rise in the liquid being pumped depends on the efficiency of the pump. In particular for an "incompressible" liquid like diesel fuel the temperature ratio across the pump is related to the entropy rise by T2/T1 = exp((s2-s1)/c) where c is the specific heat of the...

This is the formula in Timoshenko's book "Vibration Problems in Engineering", if μ is the mass density (kg/m3) as AlephZero pointed out. As an interesting side note, the higher modes are multiples of this breathing mode frequency. For n waves around the circumference, multiply the breathing...

I don't understand your hypothetical. Say you have a diatomic gas that is in thermal equilibrium with heat bath at a temperature T, and that the internal energy is distributed among the translational and rotational degrees of freedom as we have been describing. Then you want to energize just the...

Okay, let's see if I can answer some of these questions. Let's start with the misconceptions inherent in your statement above. The first obstacle is that the vacuum wheel as you have drawn it cannot work. Consider the air flowing into the entrance. The way you have drawn it, the flow...