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21h
comment How to keep a bucket of water from freezing by only natural means?
@Random832: That's because it doesn't matter much. For starters, at those high temperatures the energy loss is much higher, and secondly the energy released when water does freeze is quite high. It takes about as much energy to go from -1 C to 0C as it takes to go from 0 C to 80 C.
May
21
comment What speeds are “fast” enough for one to need the relativistic velocity addition formula?
Note that when we write "24 km/s or so", we already imply that our tolerance for input errors is several %. "24 km/s + 5 km/s = 29 km/s", with the error margins dominated by the input error regardless of the formula used to add speeds.
May
12
comment Why isn't the color of a molecule a combination of the colors of its component atoms?
It may be important to point out how those electrons interact: they can't be in the same state. Two electrons can share an orbital if the spins are opposite. In theory, electrons repulse each other, but around atomic nuclei (with all the protons) this isn't so important.
May
10
comment Physics in the movie 'INTERSTELLAR'?
(BTW, this is the plot of the 1977 novel Gateway by F.Pohl)
May
10
comment What stops the middle point of a power line from falling?
@GMB: Have you checked Wikipedia? It's fairly easy to see that the horizontal part of the tension factor cannot change as the two horizontal forces on either end of the chain are mirror-symmetric and gravity is vertical.
May
10
answered Physics in the movie 'INTERSTELLAR'?
May
7
comment Would fog impair echolocation abilities?
I'm wondering about that scanning light source. There's a rather remarkable effect that 180 degrees scattering is twice as strong as any other scattering, in the case of internal reflections. This is because the 180 degree paths are bidirectional, and have to be counted twice. Purely classical physics, this, but still a late 20th century discovery. Engineering-wise, this means that you may actually want to design for non-180 degree scattering. Underwater you're not dealing with internal reflections in a droplet so that's another matter.
May
6
comment Are there any natural phenomena on Earth that involve supersonic speeds?
"supersonic" speeds are not meaningful at small scale. The speed of sound is the sound at which pressure waves travel, i.e. the speed at which a physical displacement of atoms travels between neighboring atoms. That speed at atomic scale is meaningless for subatomic particles.
May
6
comment Are there unobservable, undiscovered atoms?
The more interesting question is whether there are undiscovered atoms which are bigger than the known atoms. Big atoms are generally radioactive and break up, but there could be big atoms that are unusually stable.
May
6
answered What triggers a nuclear chain reaction?
Apr
16
awarded  Nice Answer
Apr
14
comment Static electricity and door handles
There are thousands of tricks - keys, elbows, anything that avoids an arc from your fingers to the door handle.
Apr
14
comment Does universe calculate?
Also, what does 1/3 have to do with approximations? It's exact, and it can be used in an exact way. One third of 71 exactly 23 2/3.
Apr
14
answered Can we theoretically balance a perfectly symmetrical pencil on its one-atom tip?
Apr
10
comment In a noiseless environment, how accurate do today's transmitters send EM waves?
You're wondering about state of the art, which is essentially engineering. Scientifically you're looking at the Heisenberg uncertainty principle, ΔEΔt > ħ. E would the photon's energy, which of course is ħω so ΔωΔt > 1.
Apr
10
answered Phase change on reflection only 0 and $\pi$ allowed
Apr
8
answered Why are solar panels blue, rather than black, when black absorbs more light?
Apr
8
comment Carbon 14 disintegration
Even if the original carbon atom was rather positive (e.g. CCl4, chloroform) the excess energy is still enough to escape not just the atom but the whole molecule.
Apr
8
awarded  Organizer
Apr
8
comment Variation in spring constant with respect to the length and no. of coils
Instead of cutting the spring in half, imagine what happens if you paint a red dot on the middle. That thought experiment should tell you what happens to the halves above and below the dot.