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| Thread ID: 101245 | 2009-07-06 10:19:00 | Physics Question | Adamnz (12260) | PC World Chat |
| Post ID | Timestamp | Content | User | ||
| 789561 | 2009-07-07 02:54:00 | Interesting stuff, as in the light from the sun takes 8 minutes to get here (as ealier stated by one of the posters?) But if the sun suddenly moved would we feel the gravitation shift immediatley... Same as the polish theory, but the pipe neednt be 1 light year long to prove | Gobe1 (6290) | ||
| 789562 | 2009-07-07 02:54:00 | Bush science 101 You need to think about what you are actually doing with the push. It isnt a giant hand that grips the full length of the pole. You are apply force to the atoms at your end only, pushing them towards the neighbouring atoms, which then apply that force the their neighbouring atoms etc etc etc :help: |
sroby (11519) | ||
| 789563 | 2009-07-07 03:06:00 | Interesting stuff, as in the light from the sun takes 8 minutes to get here (as ealier stated by one of the posters?) But if the sun suddenly moved would we feel the gravitation shift immediatley... Same as the polish theory, but the pipe neednt be 1 light year long to prove Gravitational effects DO NOT travel faster then the speed of light. ask Mr Einstein Also, time is relative, not constant so if we want to be tricky we could say the light takes a fraction of a second to get here based on time as seen by the photons. Or are we measuring time from the time light take from its creation in the middle of the sun:then its much longer than 8 minutes. |
sroby (11519) | ||
| 789564 | 2009-07-07 03:23:00 | What about if you switched your torch on and started walking down the pole - would the light from your torch be moving faster than the speed of light? ;) No the light remains at the speed of light in every reference frame. but the light waves wavelength would decrease by the Doppler effect (en.wikipedia.org), getting a slightly higher frequency. which is how the cops measure your speed with their radars. |
spaceman8815 (4112) | ||
| 789565 | 2009-07-07 10:55:00 | You need relativity to explain this, since information cannot travel faster than the speed of light then the force at the other end of the pole would not occur until this information is transfered to it, thus in the reference frame of the universe the pole would seem to bend into a horse shoe shape, but in the rest frame of the pole space would seem to bend around you. This kind of science is called action-at-a-distance (en.wikipedia.org). Action-at-a-distance has nothing to do with this. The pole is a one-piece, continuous object. Action-at-a-distance would be used to try to explain something like the force between two discrete objects (i.e., gravity). |
vinref (6194) | ||
| 789566 | 2009-07-07 11:17:00 | Hi all, an idea just came into my head and I cannot figure out the answer: Assume a pole sitting in space. The pole is one light year long. There are two people standing at either end of the pole, one shines a torch at the other, the light from that torch would take 1 year to reach the other person. Now what happens if one of the people pushes the pole slightly, would the movement be transferred instantly to the other end? A couple of posters just about got it. When you push one end of the pole you create a pressure wave which will travel at the speed of sound appropriate to the material of the pole. Relativity, speed of light etc. don't come into it. More interesting, what happens when the wave reaches the other end? |
Jayess64 (8703) | ||
| 789567 | 2009-07-07 12:21:00 | When the wave reaches the other end, it reflects and snaps the pole. The ends are now poles apart and the experiment will need to be repeated with a larger budget. 25 NCEA credits for demonstrating this effect. | R2x1 (4628) | ||
| 789568 | 2009-07-07 15:13:00 | When the wave reaches the other end, it reflects and snaps the pole. The ends are now poles apart and the experiment will need to be repeated with a larger budget. 25 NCEA credits for demonstrating this effect. Pfft, I could get that many by just picking up rubbish at school. |
beeswax34 (63) | ||
| 789569 | 2009-07-07 22:16:00 | The point is, since the people and the pole are in space (i.e. a vacuum), one person pushing on the pole as described by the OP will not move the pole - he/she will simply push themselves backwards. Take a computer chair with wheels, sit on it outside, and push against your house. Do you move, or does the house move? If your house doesn't move, then why bother figuring out what happens at the other end? |
somebody (208) | ||
| 789570 | 2009-07-07 22:31:00 | Pfft, I could get that many by just picking up rubbish at school. It appears that for many, rubbish is the only thing they pick up at school. ;) |
R2x1 (4628) | ||
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