Predicting the Trajectory of a Thrown Ball on a Moving Train

[shehri]

Homework Statement

If a person is sitting in a train which's starting from rest & he throws a ball upward,then where'll the ball fall?
1)At the position where it's thrown?
2)Behind the person?
or
3) Ahead him?
Thanks.

Homework Equations

Nill.

The Attempt at a Solution

May be theory of relativity is involed,but not sure.

 

[neutrino]

All it involves are Newton's laws of motion.

 

[Mentz114]

Is the train accelerating at the moment when the ball is thrown ? Or in a state of steady motion ?

 

[shehri]

The train is accelerating while the ball's thrown.Thanks for interest.

 

[neutrino]

The train is accelerating while the ball's thrown.

What are the forces that act on the ball, along the horizontal direction, after it is thrown? (I suppose you can neglect any air-friction)

 

[christianjb]

What are the forces that act on the ball, along the horizontal direction, after it is thrown? (I suppose you can neglect any air-friction)

No- I don't think you should neglect air-friction. It changes the choice from the list of possible answers.

(Edit) Oh- I see the train is accelerating.

(Of course, 'at the position where it's thrown' is meaningless under even gallilean relativity.)

 

[neutrino]

No- I don't think you should neglect air-friction. It changes the choice from the list of possible answers.

C'mon...this is most probably a question from intro-physics/mechanics; air-friction can always be neglected.

 

[Mentz114]

If the train accelerating when the ball is tossed, the ball will cease to accelerate when it leaves the throwers hand. The thrower will therefore move relative to the ball. All you need now is the direction.

 

[useful_idiot]

Air resistance can be neglected in intro to physics and some parts of mechanics courses.

As far as relevancy to your question, the ball will move forward at whatever the velocity of the train is as it is accelerating. :zzz:


You also need to understand, once he let go of the ball from his hand, it is no longer a part of the train so it is in a different dimension whilst the train is still accelerating.

-James

 

[drpizza]

Is he on one of the seats facing forward? Or one of the seats facing backward? Last train I was on, the seats were arranged that way - facing each other.

 

[DaveC426913]

Is he on one of the seats facing forward? Or one of the seats facing backward? Last train I was on, the seats were arranged that way - facing each other.

Considering the phrasing of answers b and c 'behind him' vs. 'ahead of him', I would bet money that he's sitting in a forward-facing seat.

 

[drpizza]

Considering the phrasing of answers b and c 'behind him' vs. 'ahead of him', I would bet money that he's sitting in a forward-facing seat.

Oh, I agree with that, but I think it's something that the question writer assumed without any thought. :)

 

[KingNothing]

This is intro physics. Air has no resistance. Ever.