The Physics Of Jumping Whilst On A Train

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The Master
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The Physics Of Jumping Whilst On A Train

Post by The Master » Tue Oct 06, 2009 2:36 pm

I have a feeling this is going to sound really stupid, but...

When you're on a relatively fast moving train, and you do a little jump, how come you don't land several feet back from where you set off?

It's not a closed system; the windows can be open and everything :P On a vacuum-sealed pressurised aeroplane, I can understand it - but on a train?

Moreover, I reckon if you were on the roof of the train and performed a similar feat, you would land back a bit.

Or not?

I only ask really because the three people here I've just asked all just giggled and looked at me a bit funny like :lol:
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Fightersmegamix
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Re: The Physics Of Jumping Whilst On A Train

Post by Fightersmegamix » Tue Oct 06, 2009 3:02 pm

You're moving at the same speed as the train, why would you suddenly stop if you jumped up? If you were on the roof the wind would probably blow you back a little.

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The Master
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Re: The Physics Of Jumping Whilst On A Train

Post by The Master » Tue Oct 06, 2009 3:04 pm

Well how come when I try to replicate this experiment with a little model choo-choo train and a LEGO man, he always falls off? :?:
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The Hardest of All Freds
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Re: The Physics Of Jumping Whilst On A Train

Post by The Hardest of All Freds » Tue Oct 06, 2009 3:06 pm

Is he drunk?
Going Solo...................

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The Master
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Re: The Physics Of Jumping Whilst On A Train

Post by The Master » Tue Oct 06, 2009 3:07 pm

He's made of LEGO, of course he isn't drunk :lol:

What if you could float? I mean, I know you can't... but what if?
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Re: The Physics Of Jumping Whilst On A Train

Post by will2097 » Tue Oct 06, 2009 3:18 pm

Yeah but the Earth spins through space at 67,000Mph so why doesn't the train fall off?

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sscott
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Re: The Physics Of Jumping Whilst On A Train

Post by sscott » Tue Oct 06, 2009 3:22 pm

The Master wrote:He's made of LEGO, of course he isn't drunk :lol:

What if you could float? I mean, I know you can't... but what if?
The Master's lease on his earth flat is almost up and he must soon return to Zygon XII, he has much data to bring back and a 10 minute PowerPoint presentation to make.
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The Master
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Re: The Physics Of Jumping Whilst On A Train

Post by The Master » Tue Oct 06, 2009 3:24 pm

will2097 wrote:Yeah but the Earth spins through space at 67,000Mph so why doesn't the train fall off?
That's easy - it's because the Earth is like a big sucky magnet.

What I don't get, is why the train seems to be a bigger sucky magnet just because it's moving.

I still reckon if you were on the roof it'd be different. I'm going to have to try this.

I'm also going to need to get some sleep :lol:
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The Master
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Re: The Physics Of Jumping Whilst On A Train

Post by The Master » Tue Oct 06, 2009 3:25 pm

sscott wrote:The Master's lease on his earth flat is almost up and he must soon return to Zygon XII, he has much data to bring back and a 10 minute PowerPoint presentation to make.
I can't leave yet, I've got to stand on top of a train and that...
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Re: The Physics Of Jumping Whilst On A Train

Post by Havantgottaclue » Tue Oct 06, 2009 3:34 pm

Fightersmegamix wrote:You're moving at the same speed as the train, why would you suddenly stop if you jumped up? If you were on the roof the wind would probably blow you back a little.
Exactly - relative velocity and all that. Your relative velocity compared with the train is zero if you're standing still, whereas compared with the outside it's whatever speed the train is moving at. If the train is moving at 70mph, you're moving forward at the same rate. If a long jumper could approach the board with a forward momentum of 70mph, you'd need a sand pit at least 50m long. From that point of view if you jumped straight upward on a train, you might well move more than 50m forward with respect to the outside world.

By contrast, if a train moving forward at 70mph were to stop immediately, people are thrown forward as their own momentum cannot compensate for the sudden change of the train's momentum.

And just to think it's all made possible by the friction between the floor and your footwear. If trains were made out of ice we'd be thrown to the back in a big heap.
Soon you will have forgotten all things: soon all things will have forgotten you. (Marcus Aurelius, Meditations, Book 7)

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Re: The Physics Of Jumping Whilst On A Train

Post by sscott » Tue Oct 06, 2009 3:38 pm

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My god he's right!
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Re: The Physics Of Jumping Whilst On A Train

Post by rossi46 » Tue Oct 06, 2009 3:42 pm

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Thoughts and prayers.

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Havantgottaclue
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Re: The Physics Of Jumping Whilst On A Train

Post by Havantgottaclue » Tue Oct 06, 2009 3:42 pm

You know what's even worse? I really like those 'Last Word' questions in New Scientist - I even have a copy of the book "Why Don't Penguins' Feet Freeze", an anthology of readers' questions and answers given by other readers ...
Soon you will have forgotten all things: soon all things will have forgotten you. (Marcus Aurelius, Meditations, Book 7)

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thevulture
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Re: The Physics Of Jumping Whilst On A Train

Post by thevulture » Tue Oct 06, 2009 3:43 pm

IS this the same forum, where not so long ago the burning question was: Which do you prefer:Tea or coffee?. :lol:

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The Master
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Re: The Physics Of Jumping Whilst On A Train

Post by The Master » Tue Oct 06, 2009 4:22 pm

Considering that there's no currently accepted valid scientific explanation for how the fuck Bumblebees can actually fly, I don't think my question was too retarded :P

If I fall off, I'll never speak to you all again :twisted:
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