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Dec
9
comment If there is no gravity, does that mean there's no mass as well?
@jinawee you are attracted to the sun, along with the Earth itself. That's why we're in orbit around it. You are accelerating toward the sun, but the Earth is also accelerating as well. That's why in Earth's reference frame it can be neglected.
Dec
9
comment If there is no gravity, does that mean there's no mass as well?
I think this is actually a reasonable question. Just because the distinction is obvious to people who have a Physics background doesn't mean it isn't to everyone else.
Dec
5
comment Whistle Physics
That link is now broken; stills can still be found here. Do you know where the video is?
Dec
5
comment Why is a whistle sound emitted when air is pushed through a tight space?
See also my question.
Dec
4
awarded  Tumbleweed
Nov
29
comment How did Lord Rayleigh derive/determine the phase function for his scattering model?
People of the future: I have just confirmed by hand that the given phase function is correctly normalized (i.e., the coefficient should indeed be $\frac{3}{16\pi}$). Specifically, this causes it to integrate to one over the unit sphere, thus conserving probability.
Nov
27
asked Kármán Line Definition from “Aeronautical Flight” (Mass, Area, and Lift)
Nov
15
awarded  Notable Question
Oct
30
comment Why would it be true that people with longer legs walk faster than ones with shorter legs?
@JohnRennie, they do. But it's not enough to overcome the scaling. kleingordon, the timing of miniature people's footstrides would not be proportional. It is nonlinear. See tmac's answer.
Oct
29
comment Why Does Thin-Film Interference Manifest Visibly Only on Thin Films?
As I wrote, since rays strike in parallel, the difference between the incident and exitent point is negligible under uniform lighting. In any case, interference begins at the surface, not in your eye . . .
Oct
29
answered Pattern on mesh office chair emulates thin film interference for curved surface. Possible to form an equation?
Oct
29
asked Why Does Thin-Film Interference Manifest Visibly Only on Thin Films?
Oct
25
comment Which hemisphere am I on?
Is a wireless laptop a household item?
Oct
24
comment Where does the energy from a parachute go?
@WetSavannaAnimalakaRodVance I have indeed seen the Steak Drop article. I probably should have mentioned it myself, since it's a decent explanation. I should probably have been a bit more specific too: I want to say it's around 20% friction, 80% direct transfer--though I don't remember the source. For people of the future, GraphicsResearch==imallett (I intend to change the name).
Oct
23
comment These two operators commute…but their eigenvectors aren't all the same. Why?
Maybe math.stackexchange?
Oct
22
comment Sellmeier Refractive Index of Standard Air
+1 for the help. The squaring also generalizes to more than one term, and then just taking the lowest-order terms. I didn't know that about optical-glass manufacturers using precisely 1! The fact that a nonconstant Sellmeier formula exists for a perfect vacuum makes me unhappy.
Oct
22
awarded  Teacher
Oct
21
comment Where does the energy from a parachute go?
No. The high temperatures from reentry actually have very little to do with friction. Mostly, at these speeds, the air is compressed, which then releases heat adiabatically. The energy from spacecraft reentry is dissipated in the form of work compressing the atmosphere in front of it. This doesn't generate heat. The temperature increase is just a secondary effect.
Oct
4
answered Sellmeier Refractive Index of Standard Air
Oct
3
awarded  Editor