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Jan
24
comment Prove that time for planet to fall into the Sun equals $\left( \frac { 1 }{ 4\sqrt { 2 } } \right)$ of the planet's period
@innisfree That the question is creative does not mean that it should not be closed. Furthermore, it has no real physical relevance anyhow.
Jan
23
comment How does the cross section of a stream of falling water decrease
Your answer does not address which force in responsible for the contraction. You only prove that continuity is satisfied, but that is not really what is asked here.
Jan
23
comment How does the cross section of a stream of falling water decrease
Your answer does not address which force is responsible for the contraction.
Jan
23
comment Why do icebergs move perpendicular to the wind?
Interesting, it may be worth to be more specific in your question about the part you don't understand. Otherwise you will just get a summary of the wiki page as an answer, which probably doesnt help you.
Jan
23
comment Why do icebergs move perpendicular to the wind?
Do you have a source about the icebergs moving perpendicular to the wind?
Jan
17
comment Cooling of a surface due to fluid passing over it
You never mention this explicitly. Is the flow around your object turbulent or laminar?
Jan
17
comment Cooling of a surface due to fluid passing over it
Please add a figure that contains all the variables that you defined. It will greatly help people to understand what you are talking about, I get lost in all your definitions of axis, sizes, et cetera.
Jan
15
comment How much money can I save on gas by losing weight?
Not really. I guess all terma involving the mass that may play a role are linear in the mass (roll friction, accelation power), so it is all included
Jan
15
comment How much money can I save on gas by losing weight?
@RobertStiffler Sure, I think the average velocity is a good way to tell that.
Jan
15
comment How much money can I save on gas by losing weight?
@pentane That is exactly why I am giving a range of 0-1.6%. There is no way to tell exactly
Jan
14
comment How much money can I save on gas by losing weight?
@Aequitas Ok, that is depends on the average value does not mean that I can give you a more exact value.
Jan
14
comment Numerically solving a simple Schrodinger equation with fast Fourier transforms
I think it is very well known in most subfields of numerical physics that FFT solvers are extremely efficient in solving a subset of all problem. Periodic boundary conditions are important (or as Daniel mentions, no "real boundaries" anyhow).
Jan
14
comment Momentum of slowly spinning (viscous) fluid
What is the difference between the $v_\theta$ with a dot and with the prime in your notation? Derivative wrt to $t$ and to $r$?
Jan
10
comment How to move a bubble which is trapped by the capillary pressure?
On a sidenode: Womersly pulsatile flow is still laminar. Your statement that the flow becomes turbulent is incorrect
Jan
3
comment Composite bar in series paradox
-1 for extreme laziness of just posting a picture. If you don't care to take the time to write it out neatly (such that it is editable), why do you expect us to spend time on your question? This is insulting.
Dec
29
comment It's about capillary rise of water
You will not get a vacuum, so the one with the strongest capillary force will rise, the other one will go down.
Dec
29
comment It's about capillary rise of water
@Quark That is a bit of a different, but interesting question. If beaker is capillary size, but still larger, it's water level will still diminish. You will see that the water level in the small capillary will rise, but not as much. Try making a diagram, consider hydrostatic pressure, and the pressure drops across both menisci. Take into account that ambient pressure is the same for both. (Another interesting experiment is when you close either of the capillary).
Dec
22
comment Does steady flow imply laminar?
Ah, I see what you mean. In cases with a driving force (i.e. pipe flow), statistically stationary turbulent flow is real. I was not specifically referring to the initial phase, but rather trying to compare forever and "forever + 1 time unit"
Dec
22
comment Does steady flow imply laminar?
@Gert I don't get your point. "Turbulent flows can exist forever". I agree, but where do I say something else? I thought that was your interpretation of "transient" (i.e. non-eternal). I don't get what you mean with "normal time range" in "real application"? What I mean was, that averaging over $[t_1,t_2]$ and $[t_3,t_4]$, results in the same statistics. Can you maybe expand on your comment, so that I understand my confusion? I will then improve my answer.
Dec
22
comment Does steady flow imply laminar?
@Gert Transient means time-dependent.