Mike Dunlavey
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 Mar 10 comment How is pressure reduced on the upper part of an aircrafts wing? Ethan, maybe I've mentioned this to you before, but I would encourage you to read John Denker's on-line book about aviation. He just makes things so incredibly clear. Mar 9 answered What is the proper way to explain the twin paradox? Mar 9 comment How is pressure reduced on the upper part of an aircrafts wing? Air cannot be pulled (or pushed) by anything other than a pressure difference. Mar 7 comment What Are Logarithms? @MatthewMorrissette: Well, I was a professor once, so I don't mind answering elementary questions, but that makes me an outlier. There are people on this site who can answer questions at the cutting edge of physics. The more physics you learn, the more you will see how great this website is. Mar 7 comment Why does pressure decrease as velocity increases? It's very simple. The only way the velocity of a parcel of gas can increase is by being pulled by lower pressure (or pushed by higher). So there's a direct relationship between velocity and pressure. (A violation of this rule is if something else accelerates the gas, as in the case of a conductive plasma in a magnetic field.) Mar 7 answered What Are Logarithms? Mar 3 revised How can I understand $\mathrm ds^2 = -c\,\mathrm dt^2 + [\mathrm dx-v_s(t)f(r_s)\mathrm dt]^2 +\mathrm dy^2 +\mathrm dz^2$ in the simplest way? added 548 characters in body Feb 28 answered Would a hybrid mixed medium balloon allow you to use less helium to lift equivalent weight? Feb 25 comment Why does wind sound the way it does? @Carl: That's why I said "white" :) Feb 25 comment Why does wind sound the way it does? It depends what it's blowing through - trees, whatever. Anyway, it's "white" noise. Feb 21 comment Would a Tesla Valve create a pressure differential? @ChesterMiller: Right, I think that's what Joe was asking, and I think the electrical analog is the corresponding situation. If in Joe's boxes a pressure differential would develop, then you could have it drive a little motor in a tube going from one box to the other. Perpetual motion machine! Feb 20 revised Would a Tesla Valve create a pressure differential? added 303 characters in body Feb 20 answered Would a Tesla Valve create a pressure differential? Feb 17 comment Gravity and elliptical orbits @JeanValsean; Not if the satellite is traveling fast. In general, newtonian orbits are conic sections, like a hyperbola. In fact, you've heard of "gravity assist" to accelerate spacecraft? That's when a fast-moving object loops past a planet and picks up speed from it. In the planet's frame, the orbit is a hyperbola. Feb 17 revised How can I understand $\mathrm ds^2 = -c\,\mathrm dt^2 + [\mathrm dx-v_s(t)f(r_s)\mathrm dt]^2 +\mathrm dy^2 +\mathrm dz^2$ in the simplest way? added 314 characters in body Feb 17 revised How can I understand $\mathrm ds^2 = -c\,\mathrm dt^2 + [\mathrm dx-v_s(t)f(r_s)\mathrm dt]^2 +\mathrm dy^2 +\mathrm dz^2$ in the simplest way? added 314 characters in body Feb 17 answered How can I understand $\mathrm ds^2 = -c\,\mathrm dt^2 + [\mathrm dx-v_s(t)f(r_s)\mathrm dt]^2 +\mathrm dy^2 +\mathrm dz^2$ in the simplest way? Feb 15 comment Did/Will gravitational wave displaced earth? Thanks. Dumb questions: 1) what is spiral time? 2) how do they know it is 1.3b light years distant? Feb 14 comment Can a submarine be powered by a wind turbine? @Hohmannfan: The point is, just have the sail travel in a circle. Then the sail is not traveling directly into the wind. It is traveling at an angle to the wind, but the vehicle is traveling directly into the wind (or wherever it is pointed). Feb 14 answered Can a submarine be powered by a wind turbine?