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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 | ||
| 789541 | 2009-07-06 11:37:00 | Nothing is incompressible, (And I am assuming you are not making the pole of nothing ;) ) and nothing is inextensible either. Since the material it is made of has mass, it has inertia. Any deflection at the driven end is going to have to manoeuvre a rather long and whippy stick without the least bending. Since a light year even in leagues is a distance approaching infinity in practical terms, there is a very strong chance that the inherent self damping will have removed the disturbance long before it has propagated to the other end. Even if we go for an ideal absolutely inflexible pole, the propagation of displacement in a solid is not likely to be at the speed of light, but more likely at the speed of sound in that substance. (That is how sound is transmitted after all.) It would be a most odd substance that has a speed of sound equal to the speed of light. (At least, it is for this long after the big bang.) |
R2x1 (4628) | ||
| 789542 | 2009-07-06 11:51:00 | I think the real question is whether or not there is something with enough power to move said pole? | qazwsxokmijn (102) | ||
| 789543 | 2009-07-06 11:56:00 | And somewhere to sit the said power source. (Archimedes found this out.) | R2x1 (4628) | ||
| 789544 | 2009-07-06 11:58:00 | It's a thought experiment - and like the rest of science, it takes place in an imaginary universe in which there are no engineers or engineering considerations... | Deane F (8204) | ||
| 789545 | 2009-07-06 12:14:00 | Now what happens if one of the people pushes the pole slightly Due to the mass of the pole, and the fact that space is a vacuum, if you push the pole, you will move yourself backwards, and the pole will remain stationary (not completely, but it will move so little that it doesn't count). |
somebody (208) | ||
| 789546 | 2009-07-06 12:24:00 | Way to ruin everything ^ | --Wolf-- (128) | ||
| 789547 | 2009-07-06 12:25:00 | Crash a planet into the ****er. She will move. | Metla (12) | ||
| 789548 | 2009-07-06 12:27:00 | That is one very long pole you have. For example if the Sun we live under went out for some reason we would not know for some 8 minutes. Light travels at some 186,000 miles per second if my memory has not failed me. The proposal says that the two people are in space so I guess I can assume that either end of the said pole is only anchored by the body weight of the two people involved. A chain is not rigid as was pointed out and neither is a pole for that matter and I know this for a fact having been involved in laying pipes for town water. Now I do know that a pole is different to a pipe but if we take a crowbar and use it as a lever it usually bends (the crowbar) that is. Pipes bend as well. My view is that the reaction at the other end of the pole will not be felt at all ever in any event if one person pushed the pole. This as the speed of a push does not exceed the speed of light. In fact man or woman if you like has not ever made anything that exceeds the speed of light to date as far as I am aware. For example if I drop my end of a pole or pipe it is highly likely that my mate on the other end will see that before he feels it. R2x1 has a relevant point in so far if you and I are there and manage to get back it will take me at least 1/2 a light year to get back from my end of the pole and you as well. Unless you want to bring immortality into the equation who is going to say the experiment was successful? |
Sweep (90) | ||
| 789549 | 2009-07-06 12:33:00 | 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? No. The atomic structure of the pole would permit some deformation and stretching, however slight, giving rise to a pressure wave. This wave cannot travel faster than the speed of light. As an aside, it is said that the expansion of the universe at the Big Bang was "faster" than the speed of light. |
vinref (6194) | ||
| 789550 | 2009-07-06 12:34:00 | Jesus is faster then the speed of light. FACT. |
Metla (12) | ||
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