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Functional programming enthusiast, audio engineer & musician. Whilst not busy with any of that, I study physics at Universität zu Köln / Bonn-Cologne Graduate School.


Aug
31
revised Why is there a controversy on whether mass increases with speed?
added 927 characters in body
Aug
31
comment Why is there a controversy on whether mass increases with speed?
@BenCrowell: it is an ambiguity if the problem is phrased ambiguously (duh), i.e. if it wasn't properly specified whether both particles should be considered. Yet to the layman it's not obvious that the ambiguity carries over, because in the nonrelativistic case mass is simply additive. Hence the apparent controversy, when really you're just comparing two different situations with results that seem incompatible (but aren't).
Aug
31
comment Why is there a controversy on whether mass increases with speed?
@BenCrowell that still leaves ambiguity if it's not clear what system you consider. For two particles, if you accelerate them in opposite directions, the invariant mass increases. If you only consider one of the particles, it stays constant.
Aug
31
answered Why is there a controversy on whether mass increases with speed?
Aug
24
comment Do low frequency sounds really carry longer distances?
@akrasia: the near-field includes the eardrums (or at least the ear canal: once you're in a waveguide, all works differently anyway!). That's basically all that's relevant here, and it follows easily from the effective size of the diaphragm: larger than the distance to the ears. Ear-plugs are right in the ear canal themselves, so for those it's obviously true.
Aug
18
comment Current in purely LR DC circuit at t=0
Possibly this is the right answer (I can't tell because I don't really understand what the OP is asking), but at any rate it's imprecise wording. You don't induce currents, you induce EMFs (voltage). What Lenz's law states is that this voltage is such that the current it causes through a resistor or capacitor is such as to inhibit the change in magnetic flux. Cancelling currents in opposite directions... sure you can somehow interpret stuff like that, but I doubt it's very useful here.
Aug
18
comment Current in purely LR DC circuit at t=0
After closing what switch? If you start with an inductor and a resistor connected only at one terminal, and then connect the other one, the current will obviously start out at zero... and stay at zero forever!
Aug
15
comment Is speed an intensive property?
That's pretty convincing to me, now I read it. Perhaps what I meant to say with my original comment should better have been put "the notion of extensive-ness doesn't make sense for vector quantities", but momentum is evidently extensive, and then there is no good argument why velocity wouldn't be intensive.
Aug
14
comment Is speed an intensive property?
I think intensive vs. extensive only makes any sense for true scalar quantities, while speed is (the magnitude of a velocity-) vector. So it's neither intensive nor extensive.
Aug
14
comment What would happen if charged plates are placed horizontally?
I'm not quite convinced your argument for considering this like a thin charged wire is correct. That argument works for a parallel-plates capacitor because the field is homogeneous, but in a cylindrical field the gathering of electrons becomes ever more unfavourable with decreasing radius of the imagined wire.
Aug
14
revised What would happen if charged plates are placed horizontally?
Embedded sketch image
Aug
9
comment How do crocodiles jump?
@ChrisWhite: if you consider the resultant force not so much as thrust, rather as lift, then it's perfectly obvious to call it hydrofoil. As to why I considerer it as lift here, the question was about "counteracting gravity" – though that in itself is somewhat unfortunately put of course, since in fact there is quite some acceleration going on.
Aug
7
answered How do crocodiles jump?
Jul
29
comment Where does wave frequency come from
No. You can't have "just one wiggle". Your concept that an oscillation is a sequence of separate cycles doesn't hold, certainly not on the quantum level. What you can create is a short pulse with only a few (strong) cycles – but the shorter you want it, the more complicated it gets: as Fourier transform tells us, to get a compact peak in time we need to combine a whole lot of frequencies! That's what ultrashort-pulse lasers use.
Jul
29
comment How much more efficient is a road bike than a mountain bike?
+1 for the experiment, but really this would only answer the question if you had actually done it with both a road- and mountain bike.
Jul
29
comment What is the difference between 'flow' and 'move'?
Flow is a kind of movement – but not vice versa. A solid can only move with limited deformation so this is a movement that's not a kind of flow. — "Movement" is actually seldom defined very rigorously, sometimes it just means pure translation movement, sometimes it includes rotations (rigid body movements), and sometimes you will even allow for deformations.
Jul
29
comment What is the difference between 'flow' and 'move'?
"... that continually deforms ..."
Jul
29
comment What is the difference between 'flow' and 'move'?
The Wikipedia definition is as scientific as it gets in one sentence: "In physics, a fluid is a substance that continually deforms (flows) under an applied shear stress". What about this aren't you happy with?
Jul
29
answered Where does wave frequency come from
Jul
29
answered Peak at zero in one device and not the other