#1
Imagine...

You're on a bus travelling at 40mph, and it crashes head on into a wall. You're standing in the aisle when this happens, so you will be thrown through the windscreen. Alternative thought - What happens if you run as fast as you can, up the length of the bus (obviously in the opposite direction the bus is travelling), and jump, just before the bus crashes...

Would you basically be travelling forward, then by a seemingly invisible force, be thrown to the front of the bus, or would you continue your jump in the same direction, unaffected, as the bus collapses around you, as technically your travelling in the complete opposite direction, i just find it difficult to truly get my head around this.

P.s. was just a random thought i had one day.
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Last edited by KingHenrik1967 at May 19, 2011,
#2
You'd run into the back wall of the bus at 40mph.

EDIT: assuming you're running so as to make your speed wrt the ground zero. And a bunch of other things.

EDIT EDIT: I also managed to completely miss the bit about jumping



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Last edited by EuBoat at May 19, 2011,
#3
If you're on a bus going 40 miles per hour, and you run/jump the other way at 10 mph or however fast humans run, you're still going at 30 mph relative to the wall and you're still fucked
#4
If you were already in the air jumping towards the back, I assume you would just slam into the back door at 40mph.

This, however, is coming from almost no knowledge of physics.

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#5
unless you can run at over 40mph you'll still be moving in the direction the bus was travelling.

You'll hit the wall at a slightly lower speed but your momentum will ensure you hit the wall.
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#6
You would go through the windshield slower. Relative to the wall you are still traveling at a little less than 40mph.

Yes it would look like some imaginary force to someone strapped down safely inside the bus... outside the bus, it would look like you kept going forward when bus stopped.
#7
Depends on how fast you're running.
If you happen to be running at 40mph as the bus crashes you will stay still relative to the earth, but because you're effectively already travelling at 40mph along with the bus, anything less than that in the opposite direction would lead to you being catapulted towards the front.
#8
Newton's First Law of Motion says you will be a dead man, heading straight towards the windscreen.
#9
Quote by Ninja Vampirate
If you're on a bus going 40 miles per hour, and you run/jump the other way at 10 mph or however fast humans run, you're still going at 30 mph relative to the wall and you're still fucked


this.
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#10
The way i tried to imagine it is that the jump away from the front of the bus might somehow negate the original forward motion, as opposed to be jumping forwards... whilst you travel backwards towards a concrete doom.
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#11
Quote by KingHenrik1967
The way i tried to imagine it is that the jump away from the front of the bus might somehow negate the original forward motion, as opposed to be jumping forwards... whilst you travel backwards towards a concrete doom.


Like everyone has said, this would only work if you were a gazelle.
#12
While to you it would seem like you were going backwards, and away from harm, unless you were running very quickly you'd still hit the wall. You have to think of it from someone who's watching this happen - to them, the bus is hitting the wall at 40mph, and you running towards the back merely makes you going at, say, 30mph towards the wall.

Now, if you could run at sufficient speed off the back of the bus, and jump, you would still be flying towards the wall through conservation of linear momentum, unless you were running at 40+mph in the bus frame of reference, in which case you would jump off the back of the bus at (your speed-40)mph.

Same as in a lift, where jumping just before it hit's the floor means that instead of being at terminal velocity (assuming a long enough fall to stop accelerating), you would be at terminal minus your jump speed, still turning you into jam.

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#15
An object in motion wants to stay in motion. So you will hit the wall still because you were traveling forward (towards the wall in this case) at 40 mph. So like it's already been said unless you're running away from the concrete wall faster then 30 mph you will hit the wall

It's like when you're in a car and the car turns right but your body shifts to the left because you want to keep moving in a straight line
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#16
It'd be exactly the same as standing on a really long treadmill which is moving at 40mph.

If you stand 'still' on it, you're going to travel in one direction at 40mph. If you manage to run at 10mph the other way you're still going to be moving backwards at 30mph relative to everything not on the treadmill. In order to stay in the same place you're going to have to run at 40mph.
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#17
If the bus is going 40 mph in one direction and you, because you have some super-human-powers are able to
a) run 40 mph and
b) accelerate from 0 mph to 40 inside the bus
and you're running in the opposite direction and are in the air while the bus crashes into the impenetratable wall and the bus does not get deformed to an extent that it may crush you inside...

...well yeah, then you would survive because it would be like jumping in the same spot relative to the surface.
#18
I think that maybe... because you run in the opposite direction you will be thrown backwards, but because you're running your weight is in front of your feet (kinda hard to explain..) So you'll be thrown backwards but probably your weight thingy will slow you down...
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#19
if you actually managed to run 40mph and make the jump, then yeah, you would be fine. Any lower, and you might hit the windshield. My guess is that if you don't break like 25mph, you'll be killed.

keep in mind that you only have a very small period of time to jump. How long does it take the length of a bus traveling at 40mph to pass you? exactly.

EDIT: and its because your velocity relative to the ground will be 0 if you're moving in the opposite direction of the bus at the same speed. Assuming the back of the bus doesn't keep moving after the crash, there won't be any external forces on you.
Last edited by sporkman7 at May 19, 2011,
#20
They tested this on Mythbusters, or something like it at least. They got a truck going and pushed a sand bag or something out the back in the opposite direction at the same speed. It barely moved an inch in either direction. Very cool.
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#21
If you run 40mph and jump, won't you hit the back window at 80mph? Because the back window is travelling at 40 towards you and you are travelling 40 towards it. Depends on how good your timing is I guess.
#22
Quote by Sir Anonymous
If you run 40mph and jump, won't you hit the back window at 80mph? Because the back window is travelling at 40 towards you and you are travelling 40 towards it. Depends on how good your timing is I guess.


what the fuck?
why would you be travelling 40 mph towards the back window?


you're travelling 40 mph forwards.

you run towards the back window at 10 mph

you're now travelling 30 mph forwards

you jump

you're still travelling 30 mph forwards

you crash through the front window at 30 mph

you're travelling 0mph

you die.
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Last edited by fearofthemark at May 19, 2011,
#23
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what the fuck?
why would you be travelling 40 mph towards the back window?

He can run faster than humanly possible.
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#24
Quote by Sir Anonymous
If you run 40mph and jump, won't you hit the back window at 80mph? Because the back window is travelling at 40 towards you and you are travelling 40 towards it. Depends on how good your timing is I guess.


No, if you jump at 40mph and you jump too early, you'll hit the back window at 40mph. If you time it right it'll be as if you moved at 0mph. The only thing it's possible to hit at 80mph is the front windshield, and that's if you jump forwards 40mph just as the bus comes to a halt.
#25
TS, do you also think this is likely to work?


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#27
Quote by Ninja Vampirate
No, if you jump at 40mph and you jump too early, you'll hit the back window at 40mph. If you time it right it'll be as if you moved at 0mph. The only thing it's possible to hit at 80mph is the front windshield, and that's if you jump forwards 40mph just as the bus comes to a halt.

he means the closing speed between the back window and the person running at 40 mph the other way.

the window is moving in one direction at 40mph, the person is moving the opposite direction at 40 mph, while he's moving at 0mph relative to the ground/wall, he's moving at 80mph relative to the back window.

or am I missing something.

EDIT: nevermind. I got it.

you're already moving at 40mph with the window and the rest of the bus, so any collision would be at 40 because you'd still have your momentum going the other way as well as running 40mph at the window.
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Last edited by Lemoninfluence at May 19, 2011,
#28
Everyone is incorrect. Your only hope is to run towards the wall as fast as you can in the hopes of cancelling some of the force that it imparts on you.
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#30
you would continue going towards the back of the bus, and probably hit your head on the ceiling cuz ur tarded.
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#32
Your speed if your standing still:
O-------> (40 mph)

Your speed if your moving backwards 10 mph:
(10 mph) <-O-------> (40 mph)
Which is in total:
O-----> (30 mph)
In m/s that's 13.4 m/s

Let's say it takes you a tenth of a second from you hit the wall 'til you stop moving.

a = 13.4 / 0.1 s = 134 m/s² = 13.5 times the gravity acceleration
In reality, I think the retardation (opposite of acceleration) happens much faster though. Either way, you're ****ed.
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Last edited by sfaune92 at May 20, 2011,
#33
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ts this will only work if you can run at the speed of the bus. also to jump youre pushing the bus back and making it faster. and yourself a tiny bit slower.
Last edited by akack at May 20, 2011,
#34
You will travel back in time and help your dad get the girl he wants but the school bully called biff also wants her. Then shit happens, and the girl who happens to be your mum falls for you.
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#35
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Everyone is incorrect. Your only hope is to run towards the wall as fast as you can in the hopes of cancelling some of the force that it imparts on you.

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