Two Trains on a railway track

[potterfan3]

Two trains are travelling on the same railway track, which is 1 dimensional and long. Train one is at a position x=-5km and train 2 is at x=10km. Train two is travelling at a velocity of 90m/s, whilst train one is travelling -100m/s. If, at these positions and velocities, the trains were to brake and experience a deceleration of magnitude 20m/s/s, would they crash?

You may assume that there is nothing else causing deceleration

[wolf63]

Is that Teal'c that I see?

[potterfan3]

Indeed

[wolf63]

From one fan to another - Good day to you.

I must admit I loved Atlantis a bit more than SG1. "Save Carson Becket" campaign kept me busy for a few months.

I hope that you will get an answer to your question - totally beyond my brain's ability.

[potterfan3]

Are you on gateworld?

[factor-fiction]

Assuming you mean the trains are 15km apart initially, they will stop well before they meet

[potterfan3]

It's simplier than that

[wolf63]

I am registered on it but haven't logged on very often. I think that I am wolf63 there too.

[Prudie]

If train one has negative velocity it must be going backwards (or in the opposite direction) so they won't ever meet anyway.

[factor-fiction]

Ho Prudie- I assume that the negative value for one v means that it is travelling in the opposite direction to the other, but I suppose we need to know whether they are moving towards each other or away from each other. Anyway, whichever it is, they will not crash

[factor-fiction]

Sorry, I meant to say hi not call you a ho

[potterfan3]

____[Train One]______________________[Train Two]____
x=-5km x=0km x=10km
v=-100m/s v=90m/s
Direction <--- --->

[potterfan3]

The formatting was messed up

______[Train One]______________________[Train Two]____
_______x=-5km________x=0km____________ x=10km
_______v=-100m/s________________________v=90m
/s

Direction <--- ______________________________--->

[Prudie]

^I think that's what I said.
Ho factor, thought you were just being cool!

[jomifl]

which way are they pointing?

[factor-fiction]

Just to clarify, when I said "I assume that the negative value for one v means that it is travelling in the opposite direction to the other" I meant that if one is travelling East (say) the other is travelling West. That could mean they are moving towards each other or moving away from each other.
If they are moving towards each other then the figures are such that they will stop well before they meet (I reckon they'll still be over 14 km apart).

If they are travelling away from each other then of course they will never meet regardless of speed or deceleration rates

[jomifl]

f30, assuming space isn't curved :-)

[factor-fiction]

Good point, although I'm assuming they'd run out of power before completing a full circuit of the earth

[mibn2cweus]

20m/s/s . . . that's over 2 g's!

Can a train slow down that, err . . . fast, without crashing?

[sammmo]

I've been awake all night thinking about this.. one question .. is this british rail?

[bibblebub]

Since train 1 has x < 0 with dx/dt < 0 and train 2 has x > 0 with dx/dt > 0 they are travelling away from each other, and since the question specifically says that it is all 1 dimensional - would need at least 2 dimensions for the track to be on a surface - they will never meet.

p.s. won't get many passengers on those trains.