Length contraction depends on the distance of the object?

In summary, the conversation discusses a problem about length contraction in a train moving at a constant speed of 0.5c. The question asks about the visual appearance of length contraction for a particular observer, rather than the actual measured length contraction. The expert clarifies that the actual measured length contraction is the same for all observers within a frame and does not depend on distance from a specific observer. The conversation also includes a visual representation of the scenario, with the expert suggesting to redraw the diagram to show the worldlines of the front and rear of the train.
  • #1
Shukie
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http://home.orange.nl/kuip3148/phys1.JPG [Broken]

Not exactly homework, but a problem I found in my lecture notes. The train is moving at a constant speed 0.5c. Question b asks what the length of the train will be then at t = -1. From what I understand, this suggests that length contraction depends on the distance the object is away from an observer? So at t = -5 the length contraction would be different?
 
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  • #2
It seems that this problem is asking about the visual appearance of length contraction as seen by a particular observer, not the actual measured length contraction--which is obtained after accounting for light travel time and is the same for all observers within a frame. The actual measured--not just "seen"--length contraction does not depend on distance from any particular observer, since it's not a simple visual effect.
 
  • #3
Thanks for your answer. I'm just trying to visualize what is going on and so I made a drawing. Can you tell me if this is in any way resembles what is actually going on?

http://home.orange.nl/kuip3148/phys2.GIF [Broken]

The green line would be the length Bob observes, while the black thingy denotes the actual length of the train.
 
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  • #4
Redraw your diagram to show the worldlines of the front and rear of the train. They should be parallel, but not overlapping.
 

1. How does the distance of an object affect length contraction?

The closer an object is to the observer, the more pronounced the length contraction effect will be. This means that if an object is moving towards the observer, the observer will see the object as shorter than it actually is due to the distance between them.

2. Does length contraction only occur with objects that are moving towards an observer?

No, length contraction can also occur with objects that are moving away from an observer. However, in this case, the object will appear longer instead of shorter due to the distance between them increasing.

3. Is length contraction a real physical phenomenon?

Yes, length contraction is a real physical phenomenon that has been observed and confirmed through various experiments, such as the Michelson-Morley experiment and the Hafele-Keating experiment.

4. Does length contraction only occur in objects that are moving at high speeds?

No, length contraction can occur at any speed, but it becomes more noticeable in objects that are moving at speeds close to the speed of light. At everyday speeds, the effects of length contraction are too small to be observed.

5. Can length contraction be explained by the theory of relativity?

Yes, length contraction is a consequence of Einstein's theory of special relativity. According to this theory, the observed length of an object is dependent on the relative speed and direction of the object and the observer.

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