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  • 46 votes cast
Feb
2
awarded  Nice Question
Feb
1
comment Why is UHF so much more popular than other frequencies for radio?
@Qmechanic: I seriously considered it, but I decided against - there's no actual electrical engineering in this question, just what is potentially a product of it. A bit like asking an Arquade question on Gamedev.SE.
Feb
1
comment Why is UHF so much more popular than other frequencies for radio?
I believe the range loss due to higher power requirements is as much of a disadvantage as an advantage, allowing local radio stations to share the channel if separated by sufficient distance.
Feb
1
accepted Why is UHF so much more popular than other frequencies for radio?
Feb
1
comment Why is UHF so much more popular than other frequencies for radio?
@Urgje: What is understood by bandwidth in relation to analog broadcasts? Frequency range occupied by a single broadcast (not to overlap a neighboring broadcast)? Or higher dynamic range of encodable audio, or something else yet? In digital it's clear, you can squeeze more data into the same channel, meaning multiple broadcasts or HD broadcast on a single frequency, but in analog?
Feb
1
comment How can gravity truly be infinite?
Actually, gravity does have a finite range - since it propagates at speed of light, it can't reach behind the cosmic event horizon due to space expansion "outrunning" it.
Feb
1
asked Why is UHF so much more popular than other frequencies for radio?
Jan
25
comment Lorentz contraction of object in circular motion
You don't have to. I can look up any equations just fine, it's just that going from an equation to a picture with a setting more complex than a couple points takes unreasonable amount of time and work.
Jan
25
comment Lorentz contraction of object in circular motion
Thanks. I really wish there was some relativistic Algodoo. It would make visualising what goes on much easier.
Jan
25
comment What happens to wheels of a car moving near speed of light?
@mwengler: Thanks, that's immensely helpful.
Jan
25
comment Lorentz contraction of object in circular motion
Thank you very much! May I ask what software were you using?
Jan
25
accepted Lorentz contraction of object in circular motion
Jan
25
comment Lorentz contraction of object in circular motion
Let us continue this discussion in chat.
Jan
25
comment Lorentz contraction of object in circular motion
@CuriousOne: I know the formula. And I know they will be "arriving to the near side of the ring" much slower than they are "departing to the far side" as result. And I'm completely baffled as to what happens in between and the whole thing doesnt get congested...
Jan
25
comment Lorentz contraction of object in circular motion
@CuriousOne: There's also the density (spacing) and speed of individual particles. In particular, the "returning" particles would exceed speed of light relative to O2 if something doesn't happen with them in O2's frame of reference, that would prevent them from doing so. Imagine "classic" speed addition: particles on one side move in the same direction as O2, so 0.9-0.2=0.7c. The ones on the opposite side: 0.9+0.2=1.1c.
Jan
25
comment Lorentz contraction of object in circular motion
@CuriousOne: The caveat here is that particles on one side of the circle move at different speed relative to O2 than on the other side. It's not an immobile round object, but a rotating one.
Jan
25
comment Lorentz contraction of object in circular motion
@Numrok: You're not missing anything. Observing one single particle moving in a circular path would be sufficient. Introducing a ring instead of a single particle is just to avoid the mess with simultaneousness as in any moment of movement of the observer the single particle. And I used a cloud of particles instead of a ring because I definitely wanted to avoid having any solid object here, as it would inevitably invoke the curse of 'infinitely rigid rod'. Assume charged particles in a magnetic field, no significant gravitational effects.
Jan
25
comment Lorentz contraction of object in circular motion
@JohnRennie: Preferably both, regarding your first case. As for the second, v1 is not entirely negligible. I set it to a relatively small value to stop the suspicions of "infinitely rigid rod with ends moving faster than speed of light" (that had murdered my previous question), but as I wrote, let's assume it's 0.2c relative to O1's frame: The relativistic behaviors relative to O1 are negligible, but they are definitely pronounced relative to O2. They are definitely not stationary in any of these frames though. (also, it's a momentary linear velocity in rotary motion.)
Jan
25
asked Lorentz contraction of object in circular motion
Jan
24
comment What happens to wheels of a car moving near speed of light?
@DanielGriscom: More like extension of that into a plane/field of particles. I've got a fairly good idea what happens to any single particle when translating linear motion between two frames of reference, but I both fail to grasp a larger group moving together at varied speeds and imagine any more complex motion, like rotary.