Jumping vertically on a moving train....

[Marvinski87]

I'm clueless when it comes to physics, so forgive me if this sounds stupid. But fot years I've wondered something, and no one seems to have an answer for it.

If you are standing inside a moving bus or train, and you jump on the spot (straight up,not in the direction that the vehicle is moving) then how come you land on the same bit of flooring that you started on? The vehicle is moving, so shouldn't it have left you behind slightly,thus you land further down the vehicle?? If that makes sense? Someone enlighten me please

 

[russ_watters]

Welcome to PF!

This is Newton's first law:
https://en.wikipedia.org/wiki/Newton's_laws_of_motion

First law: When viewed in an inertial reference frame, an object either remains at rest or continues to move at a constant velocity, unless acted upon by a force.[2][3

Or more broadly, the Principle of Relativity:
https://en.wikipedia.org/wiki/Galilean_invariance

Galileo Galilei first described this principle in 1632 in hisDialogue Concerning the Two Chief World Systems using the example of a ship traveling at constant velocity, without rocking, on a smooth sea; any observer doing experiments below the deck would not be able to tell whether the ship was moving or stationary.

 

[davenn]

The vehicle is moving, so shouldn't it have left you behind slightly,thus you land further down the vehicle??

no ... think about it a moment before I give an answer

what is the immediate relationship between you, everything else in the vehicle and the vehicle ?

your same Q could be asked for when you jump up off the ground (up off the earth)
after all it's rotation speed is much faster ... equatorial speed of 465.1 m/s, 1,674.4 km/h or 1,040.4 mphDave

 

[davenn]

Welcome to PF!

This is Newton's first law:
https://en.wikipedia.org/wiki/Newton's_laws_of_motionOr more broadly, the Principle of Relativity:
https://en.wikipedia.org/wiki/Galilean_invariance

damn you posted whilst I was still typing
was hoping to get the OP to do some thinking about the problem

D

 

[Marvinski87]

Thanks for taking the time to reply guys. But let me stress something. I'm thick as s**t. So russ watters I'm afraid that went over my head a bit... could you explain a bit simpler please mate. Much appreciated

 

[A.T.]

The vehicle is moving

Movement is relative. The vehicle is not moving relative to you.

 

[davenn]

You, everything in it and the train, bus etc are moving at the same speed

That's what I wanted you to figure out

So when you jump up, you are still moving at that speed, there is nothing to slow you down,
so you end up landing in the same place you jumped from

 

[Marvinski87]

You, everything in it and the train, bus etc are moving at the same speed

That's what I wanted you to figure out

So when you jump up, you are still moving at that speed, there is nothing to slow you down,
so you end up landing in the same place you jumped from

Right ok I think I get it...So say if you were on the roof of the train as opposed to inside,and you jumped..you wouldn't land on the same spot then would you?

 

[davenn]

Right ok I think I get it...So say if you were on the roof of the train as opposed to inside, and you jumped..you wouldn't land on the same spot then would you?

that's true, because (say on a calm, no wind day) there would still be significant wind resistance against you and would cause you to land behind the point you jumped from

adding a wind from any direction will vary the results

Dave