And lo on Mon, 07 Jan 2008 11:44:23 -0000, Warp <war### [at] tagpovrayorg> did  
spake, saying:

> Phil Cook <phi### [at] nospamrocainfreeservecouk> wrote:
>>  From an outside observer's pov both trains are shorter then the double
>> track so should pass without problem; I was trying to reconcile it with
>> the traindrivers' view. The oncoming train is shorter, but so is the
>> double track; so they should still collide?
>
>   From the POV of one of the trains the other train is shortened *more*
> than the track.

If they were travelling at the same speed I'd have thought that the  
shortening of both track and train would be proportional from the view of  
the other train?

-- 
Phil Cook

--
I once tried to be apathetic, but I just couldn't be bothered
http://flipc.blogspot.com

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Phil Cook <phi### [at] nospamrocainfreeservecouk> wrote:
> If they were travelling at the same speed I'd have thought that the  
> shortening of both track and train would be proportional from the view of  
> the other train?

  The trains travel at the same speed (in relation to the track) but in
opposite directions. Thus from the POV of one of the trains the other
train is approaching faster than the double track.

-- 
                                                          - Warp

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And lo on Mon, 07 Jan 2008 12:38:14 -0000, Warp <war### [at] tagpovrayorg> did  
spake, saying:

> Phil Cook <phi### [at] nospamrocainfreeservecouk> wrote:
>> If they were travelling at the same speed I'd have thought that the
>> shortening of both track and train would be proportional from the view  
>> of
>> the other train?
>
>   The trains travel at the same speed (in relation to the track) but in
> opposite directions. Thus from the POV of one of the trains the other
> train is approaching faster than the double track.

Okay I'm the driver of one train and you're the driver of the other.

I see that your train is shorter then the double section of track and that  
you're travelling faster then I am, therefore you hit the double section  
before I do. But my train is still the same length as the double track (or  
longer), so although I can clear the section without hitting the end of  
your train (because you're shorter) I would expect you to hit the end of  
my train (because you're faster).

I mean I can it understand how it works from Darren's perspective sitting  
by the track, just not from the drivers.

-- 
Phil Cook

--
I once tried to be apathetic, but I just couldn't be bothered
http://flipc.blogspot.com

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And lo on Mon, 07 Jan 2008 15:01:51 -0000, Phil Cook  
<phi### [at] nospamrocainfreeservecouk> did spake, saying:

> And lo on Mon, 07 Jan 2008 12:38:14 -0000, Warp <war### [at] tagpovrayorg>  
> did spake, saying:
>
>> Phil Cook <phi### [at] nospamrocainfreeservecouk> wrote:
>>> If they were travelling at the same speed I'd have thought that the
>>> shortening of both track and train would be proportional from the view  
>>> of
>>> the other train?
>>
>>   The trains travel at the same speed (in relation to the track) but in
>> opposite directions. Thus from the POV of one of the trains the other
>> train is approaching faster than the double track.
>
> Okay I'm the driver of one train and you're the driver of the other.
>
> I see that your train is shorter then the double section of track and  
> that you're travelling faster then I am, therefore you hit the double  
> section before I do. But my train is still the same length as the double  
> track (or longer), so although I can clear the section without hitting  
> the end of your train (because you're shorter) I would expect you to hit  
> the end of my train (because you're faster).
>
> I mean I can it understand how it works from Darren's perspective  
> sitting by the track, just not from the drivers.

Ah got it I think. Although both trains hit the double track at the same  
time from my train you haven't reached it yet, so if I see you as 1/4 of  
the length of the section I can be halfway along the double track before  
you've even got on it. So I'll reach my end when you're clear and you  
won't reach your end (despite being faster) until I've cleared your end  
(my start).

Ouch yeah that works, we each perceive the other as reaching the double  
section after ourselves.

-- 
Phil Cook

--
I once tried to be apathetic, but I just couldn't be bothered
http://flipc.blogspot.com

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Phil Cook wrote:
> And lo on Fri, 04 Jan 2008 19:19:43 -0000, Darren New <dne### [at] sanrrcom> 
> did spake, saying:
> 
>> Phil Cook wrote:
>>> Though won't the double track also seem foreshortened?
>>
>> Yes, but the oncoming train will seem *more* foreshortened.
>>
>>> travelling so fast it'll just sail straight over the gap without 
>>> falling far enough to get stuck.
>>
>> Not ... exactly. The problem isn't that he doesn't fall far enough. 
>> The problem is that the bottom of the train starts falling before the 
>> top does, kind of.
>>
>> And in that case, there are only two speeds involved (the track and 
>> the train), rather than the three in Warp's original problem.
> 
>  From an outside observer's pov both trains are shorter then the double 
> track so should pass without problem; I was trying to reconcile it with 
> the traindrivers' view. The oncoming train is shorter, but so is the 
> double track; so they should still collide?

No, because the oncoming westbound train is coming at the eastbound 
train faster than the tracks are coming at the eastbound train, so the 
westbound train appears to be smaller than the siding as seen from the 
eastbound train.

-- 
   Darren New / San Diego, CA, USA (PST)
     It's not feature creep if you put it
     at the end and adjust the release date.

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"Warp" <war### [at] tagpovrayorg> wrote in message 
news:477fd1d1@news.povray.org...
> pan <pan### [at] syixcom> wrote:
>> This could only be true if the trains and the track are 
>> uncoupled.
>> They are not, so any contraction of trains will apply equally to
>> the
>> track.
>
>  Nope. The trains are moving at a different speed than the track 
> and
> thus the trains compress more.
>
> -- 
>                                                          - Warp

Train wheels gripping track exponentially gets looser
the greater the speed of the train. At c or near c the
track will have to move almost the entire speed of the
train; else the instability will overwhelm your system.

ergo: the track and train muts be coupled, else you
would be asking about trains and tracks on separate
unique vectors. (Unpredictable vectors btw)

unless of course your train wheels and track rails are
made of unobtanium held together in the grip of
stick-but-slick-enough-to-let-the-wheels-move goop.

Think dentures under a lot of strain.

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pan <pan### [at] syixcom> wrote:
> Train wheels gripping track exponentially gets looser
> the greater the speed of the train. At c or near c the
> track will have to move almost the entire speed of the
> train; else the instability will overwhelm your system.

> ergo: the track and train muts be coupled, else you
> would be asking about trains and tracks on separate
> unique vectors. (Unpredictable vectors btw)

> unless of course your train wheels and track rails are
> made of unobtanium held together in the grip of
> stick-but-slick-enough-to-let-the-wheels-move goop.

> Think dentures under a lot of strain.

  I don't even understand what you are trying to say.

  But if the contact with the train and the track bothers you, then
assume maglev.

-- 
                                                          - Warp

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>  But if the contact with the train and the track bothers you, then
> assume maglev.

What about when the trains have to turn when the track splits?  That is the 
bit that bothers me most at those speeds...

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scott <sco### [at] laptopcom> wrote:
> What about when the trains have to turn when the track splits?  That is the 
> bit that bothers me most at those speeds...

  The trains and the double track segment can be really long, meaning that
the turn can be very subtle.

-- 
                                                          - Warp

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And lo on Mon, 07 Jan 2008 17:32:22 -0000, Darren New <dne### [at] sanrrcom>  
did spake, saying:

> Phil Cook wrote:
>> And lo on Fri, 04 Jan 2008 19:19:43 -0000, Darren New <dne### [at] sanrrcom>  
>> did spake, saying:
>>
>>> Phil Cook wrote:
>>>> Though won't the double track also seem foreshortened?
>>>
>>> Yes, but the oncoming train will seem *more* foreshortened.
>>>
>>>> travelling so fast it'll just sail straight over the gap without  
>>>> falling far enough to get stuck.
>>>
>>> Not ... exactly. The problem isn't that he doesn't fall far enough.  
>>> The problem is that the bottom of the train starts falling before the  
>>> top does, kind of.
>>>
>>> And in that case, there are only two speeds involved (the track and  
>>> the train), rather than the three in Warp's original problem.
>>   From an outside observer's pov both trains are shorter then the  
>> double track so should pass without problem; I was trying to reconcile  
>> it with the traindrivers' view. The oncoming train is shorter, but so  
>> is the double track; so they should still collide?
>
> No, because the oncoming westbound train is coming at the eastbound  
> train faster than the tracks are coming at the eastbound train, so the  
> westbound train appears to be smaller than the siding as seen from the  
> eastbound train.

Check my later comments on how this could still mean they collide; I think  
I've got it now anyway thanks.

-- 
Phil Cook

--
I once tried to be apathetic, but I just couldn't be bothered
http://flipc.blogspot.com

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