Simple Physics?

[monster_munch]

I've wondered this since I was a small boy and I've never been able to come up with my own answer, or remembered the conumdrum to ask a friend.

How come when you're on a train moving at speed and you jump in the air, you don't fly to the back of the carriage, as the train is moving and the air ** jumping into is not the same air but behind you now?

 

[geuben]

Because you are also moving forwards at the same speed as the train, if you could stay in the air long enough you would start to slow down relative to the train and would end up further back than you started, also the air in the train is moving at the same speed as you and train otherwise you would feel a breeze constantly.

 

[G-MAN2004]

Because you are also moving forwards at the same speed as the train, if you could stay in the air long enough you would start to slow down relative to the train and would end up further back than you started, also the air in the train is moving at the same speed as you and train otherwise you would feel a breeze constantly.

What if you run the opposite direction the train is going, then jump up at the end?

 

[stevenazari1]

yep as above, which is why when you stick your head out of the window the wind goes into your face, technically your head is going into the air as its you disturbing the air and not the other way round.

/edit
its trains force - your backwards force = actual force, but you will still be rushed in the same direction of the train as the train is traveling at a far greater speed.

 

[geuben]

What if you run the opposite direction the train is going, then jump up at the end?

If you are running as fast as the train is moving, but in opposite directions, and then jump off the end of the train. In theory you should from an observers point of view (not on the train) appear to jump straight up in the air and land back down again from the same spot (but on the tracks not the train) that u jumped from. I think.

 

[SpeedFreak]

Are you really iBot?

 

[stevenazari1]

lolz!

 

[eLbot]

Are you really iBot?

Comments like this make me wish I didn’t have such a similar name

 

[RobH]

Okay how about this, you jump whilst you are on the train, does the train get lighter whilst you are in the air?

 

[geuben]

Okay how about this, you jump whilst you are on the train, does the train get lighter whilst you are in the air?

The mass of the train and passengers will decrease yes, but the weight of the train wont, as the force you exhert on the train to make you jump, balances out loss of the force you mass exhersts just standing there.

 

[Dist]

Okay how about this, you jump whilst you are on the train, does the train get lighter whilst you are in the air?

as proved in mythbusters, in a closed environment like a lorry or train, objects inside the train can jump up or fly and the weight of the vehicle wont change.

 

[Dist]

sorry, double post

 

[SpeedFreak]

weight is a force. Newtonian physics 101, every action has an equal and opposite reaction.
Jumping involves acceleration while in contact with the floor of the train. As such, in order for you to accelerate upwards, the train must accelerate downwards, therefore increasing it's weight during the acceleration. Once you are out of contact with the floor, the train returns to it's original weight.

If you were to hover a remote controlled helicopter inside the train, the weight of the train would remain the same as if the helicopter was on the floor.

 

[geuben]

weight is a force. Newtonian physics 101, every action has an equal and opposite reaction.
Jumping involves acceleration while in contact with the floor of the train. As such, in order for you to accelerate upwards, the train must accelerate downwards, therefore increasing it's weight during the acceleration. Once you are out of contact with the floor, the train returns to it's original weight.

If you were to hover a remote controlled helicopter inside the train, the weight of the train would remain the same as if the helicopter was on the floor.

As the thread title has the word simple in it, i chose to leave out details and try and explain it in laymans terms. The helicopter thing, what about the force of the air the helicopter is displacing downwards? does that not exhert a force on the floor of the train?

 

[SpeedFreak]

As the thread title has the word simple in it, i chose to leave out details and try and explain it in laymans terms. The helicopter thing, what about the force of the air the helicopter is displacing downwards? does that not exhert a force on the floor of the train?

hence the force it exerts is the same whether hovering in flight or at rest.

 

[geuben]

hence the force it exerts is the same whether hovering in flight or at rest.

Huh? did you edit your post?

 

[SpeedFreak]

Huh? did you edit your post?

no, it was always in there.

 

[geuben]

no, it was always in there.

you lie. I though id misread it, due to it being late. I understood it to mean that if you hovered a helicopter inside the train, the train would weigh less than with the helicopter sat on the floor.

 

[SpeedFreak]

you lie. I though id misread it, due to it being late. I understood it to mean that if you hovered a helicopter inside the train, the train would weigh less than with the helicopter sat on the floor.

I have a Physics degree so I hope I wouldn't say something that silly

 

[geuben]

I have a Physics degree so I hope I wouldn't say something that silly

I have a serious lack of sleep and a messed up body clock, but I stand by it not being there

Edit: also, i have almost 3/4 of an electronic engineering degree, yet I still say silly things when it comes to electronics.