moving frame

[spunnery]

consider a train moving at a constant velocity. let the top of the train be open.drop a ball verticaly to the train from a bridge ,while train is crossing the bridge.What will be the path ball.Again drop the ball when the train is stopped below bridge. In both cases the ball will hit the floor of train at different places.Can it be considered as a physical experiment showing different results of same experiment for a body at rest and a body moving at a constant velocity?

Now can we call the moving train as an inertial frame.

[swansont]

It's not the same experiment if the train is moving relative to the bridge in one case, and not moving relative to the bridge in the other.

[spunnery]

It's not the same experiment if the train is moving relative to the bridge in one case, and not moving relative to the bridge in the other.

Ok i agree.Shall i try to say with one example,that accelerating frames are also inertial frames.But only thing is that we have to make corrections to the results,considering the aceeleration.

for example;

Case1 - train is moving at a constant speed.

A person inside the train dropped a ball verticaly down.At the instance he dropped the ball,both ball and train have same horizontal velocity.Gravity pull the ball down.Resultant of the horizontal velocity and vertical gravity will bring the ball through the diognal of paralellogram,.In the mean time floor of train (with the person)will travel equal horizontal distance,as ball has travelled.So the ball will hit the floor of train verticaly down the person,since the final position of the person is changed.

Case-2 -the train is moving at an acceleration.

The ball dropped,in this case will have the velocity ,V1 of the train at that instance(inertia?).Now the ball will travel through the diognal of parralellogram drawn with v1 and gravity.but the train ,is acellerating(it will have a greater velocity and will be displaced horizontaly more,with respect to the ball).The floor and person will move little further than the point (depending on rate of acceleration)where ball will hit the floor.So the observer will see the ball hit the floor behind him(and this is true).Does any physical laws changed here?.only thing is you have to give appropriate value to the final position of the person(observer).

[swansont]

That sounds right. What's the issue with this?

[spunnery]

That sounds right. What's the issue with this?

Issue is that physical laws are not changed in any frame.How comes light can break the law(to be constant to all observers)?.Why the simple logic in this problem not applicable to light?

Does any physical laws are changing when you travel at a speed nearer to light?.I think only thing is you have to rewrite the formulas according to the position (space co-ordinate at the instance)of the observer.

[swansont]

Issue is that physical laws are not changed in any frame.How comes light can break the law(to be constant to all observers)?.Why the simple logic in this problem not applicable to light?

Does any physical laws are changing when you travel at a speed nearer to light?.I think only thing is you have to rewrite the formulas according to the position (space co-ordinate at the instance)of the observer.

 

You haven't changed any physical laws.

 

Light speed is constant to any inertial observer. An accelerating observer will not, in general, measure the speed of light to be c.

[spunnery]

You haven't changed any physical laws.

 

Light speed is constant to any inertial observer. An accelerating observer will not, in general, measure the speed of light to be c.

So why the paradox,Inspector chasing the light at .99c observe the light travelling at c?.This can be happen only if source of light is also moving at 0.99c,Otherwise he will observe the light with just 0.01c (same as the difference between the ball dropped from bridge and ball dropped from inside the train).

Correct me ,if i am wrong?

Otherwise in general ,we can say all the physical constants remain same to any inertial observer

[swansont]

The person "chasing" the light considers himself to be at rest. His frame has to see light travelling at c. That limitation has certain consequences, one of which is that Galilean transformations aren't correct (e.g. speeds won't add linearly)

[Bignose]

Part of the problem here spunnery is that you went from Classical Mechanics to Relativity pretty quickly there. Physics on the Classical/Newtonian scale do not work when you start getting into discussions about velocities near the speed of light. 0.99c definately falls into that area. So, the same logic that does work on the Newtonian scale (trains) does not apply on the relativistic scale.