5,363 reputation
1914
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location somewhere on earth
age 60
visits member for 4 years, 1 month
seen 1 hour ago

1h
answered Athletics on the moon
1h
comment Coriolis Effect vs airplane
@pittacus: Why do you say the airplane is going to end in (an)other place? If the atmosphere rotates with the earth and there is no wind it will also follow a line of longitude. Yes, the car automatically corrects for Coriolis by friction of its tires. The airplane will have to correct as well, but it is rather small.
1h
comment Non-linear relationship between power supplied and perceived brightness in a filament lamp?
How did you measure perceived brightness? If you used the visible spectrum, the increasing temperature as the power goes up will shift more of the output into the visible. If you measure total output over the whole spectrum, the relationship should be linear.
9h
answered Coriolis Effect vs airplane
May
19
comment In which direction does mud fly off a moving bike's tire & why?
At the moment the mud releases, the centripetal force matches the centrifugal force-that is what chooses the moment of release.
May
19
answered In which direction does mud fly off a moving bike's tire & why?
May
19
comment Why electric field inside charged conductor is zero in the electrostatic case
You can then apply Gauss' law to a surface just inside the outer surface of the conductor. There is no net charge inside the surface, no electric field inside the conductor, and no surface charge on the inner surface, so no E field inside.
May
19
comment Why electric field inside charged conductor is zero in the electrostatic case
@Algohi: you are approaching this question at the proper level. I would suggest ignoring quantum mechanics and the unit electron charge for this purpose. The point is that the charges in the conductor will distribute themselves so that the internal field is zero. You will get a minus charge next to each positive charge so there is no field going into the conductor. Your are correct that the conductor is neutral, so the positive charge must appear somewhere. It will be spread around the exterior surface in such a way that the field lines hit the conductor perpendicularly.
May
18
comment Why electric field inside charged conductor is zero in the electrostatic case
@JanHudec: This whole calculation ignores both quantum effects and the fact that electrons are indivisible. When we call something a "perfect conductor" we do that. Charges have to be able to move to eliminate the fields inside the conductor. We also don't worry about the thickness of the screening layer. These are all simplifying assumptions that are close enough for many practical purposes.
May
18
comment Why electric field inside charged conductor is zero in the electrostatic case
If the charges are embedded in a conductor, the charges don't matter any more. The conductor is an equipotential with that Q. If it is a spherical shell, the field inside is zero and the field outside is the same as if it were a point charge. If it has a more complicated shape, the field inside is still zero, but you need to solve Poisson's equation outside. Far away, the field will be similar to a point charge. The shape will introduce dipole, quadrupole, etc. moments, but those will die away with higher factors of $r$ than the square.
May
18
answered Why electric field inside charged conductor is zero in the electrostatic case
May
18
comment How hot would tritium water be?
Yes, the total energy gets split between the electron and anti-neutrino. The nucleus takes up the momentum and is so heavy it doesn't take up significant energy. Wikipedia says the total energy is 18.6 keV and the electron averages 5.7 keV-I had guessed it would get half.
May
18
comment How hot would tritium water be?
The energy deposition in the water should be cut in half because there is an anti-neutrino produced which does not deposit its energy in the water. A factor 2 does not change the conclusion much. Good answer.
May
9
answered Similarity between particles and antiparticles
May
9
comment Both Special and General Relativity carry long term unresolved paradoxes. Should not they now be “inconsistencies”?
There are two senses of paradox. One is a true inconsistency. If that were found, we would invalidate the theory it was found in. The other is a perceived paradox, like the twin paradox in SR. When you analyze it properly, there is no inconsistency, but it can be stated in a way that seems to be a paradox. As far as I know, there are no true inconsistencies in SR or GR. If you believe there is one, you should be specific about stating it and ask how or if it has been resolved.
May
7
comment Both Special and General Relativity carry long term unresolved paradoxes. Should not they now be “inconsistencies”?
Neither of these theories have paradoxes. Both have limits to their applicability. SR only works in inertial frames, but is approximately right if accelerations are small, which they often are. GR works in accelerated frames, and as far as we know it is perfect outside the quantum limit. What paradoxes are you referring to?
May
7
comment Both Special and General Relativity carry long term unresolved paradoxes. Should not they now be “inconsistencies”?
Your title claims that SR has problems, but you don't mention them in the body at all.
May
7
answered Both Special and General Relativity carry long term unresolved paradoxes. Should not they now be “inconsistencies”?
May
1
comment If a bell is rung in a perfect vacuum and is suspended by opposing magnets will it ever stop ringing?
You should say that the magnetic force does not act as a damper-the only dissipation is the friction as the objects deform.
May
1
comment If a bell is rung in a perfect vacuum and is suspended by opposing magnets will it ever stop ringing?
You have missed that the only energy dissipation is friction in the distortion of the objects. Without that, the vibration would go on forever.