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Basic Time Dilation and Relativity Questions

by Epsillon
Tags: basic, dilation, relativity, time
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Oct27-08, 11:53 PM
P: 70
1. The problem statement, all variables and given/known data
1) The time-dilation effect is sometimes expressed as "moving clocks run slowly" Actually, this effect has nothing to do with motion affecting the functioning of clocks. What then does it deal with?

2) Will two events that occur at the same place and same time for one observer be simultaneous to a second observer moving with respect to the first?

3)You are in a windowless car in an smooth train. Is there any physical experiment you can do in the train car to determine wether you are moving?

4)Does time dilation mean that time actually passes more slowly in moving refrence frames or that it only seems to pass more slowly?

3. The attempt at a solution
1)This is very hard cause it doesent really makse sense cause we just started learning about this. Well my answer would be that when moving faster light travels more therefore more time?? But regular clocks dont have cloks in them

2) yes if they happen in the SAME place wouldnt be simultanous to both?

3) there is nothing you can do cause all laws of motion are similar in two reference frames

4) Actually passes more slowly?
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Oct28-08, 05:08 AM
Sci Advisor
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P: 4,300
For 1) I'm not sure what your grader would like to hear. But first of all, remember whenever you talk about "motion", that there is no "absolute motion". Secondly: is time dilation an effect of the clock? Or is it more fundamental (what do we use clocks for?)

For 2) I can give you a clear answer. Consider someone who is precisely in the center of a smoothly moving train and suppose two lasers are fired simultaneously from each end of the train, towards the middle. Will the passenger conclude when he calculates the time the lasers were fired. What would someone outside the train see?

3) is correct and very important. It means that two observers moving at constant velocity relative to each other can never do an experiment to decide whether one of them is "absolutely at rest".

4) is a bit of a trick question. If each observer looks at their own watch, they will see no strange effects, even if they are moving at 99% of the speed of light relative to the other. Time doesn't seem to pass more slowly for any of them, nor does it actually do. So please try to be more specific in your answer.

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