What Happens to a Fly Inside a Moving Train?

[semc]

Fly in a train!

Hey guys, i was wondering what happens if an object is suspended in mid air inside a moving train? Why doesn't the object just fly back to the back of the train when the train starts moving? I mean it has got no contact with the train so it will not have the velocity of the train right??

 

[Doc Al]

I mean it has got no contact with the train

How is it suspended?

 

[bp_psy]

Why doesn't the object just fly back to the back of the train when the train starts moving?

It actually does. More precisely the fly remains stationary with respect to the ground while train accelerates so it appears to be moving back to an observer in the train.It is a consequence of the first law.

 

[semc]

How is it suspended?

its just like a fly in a train

It actually does. More precisely the fly remains stationary with respect to the ground while train accelerates so it appears to be moving back to an observer in the train.It is a consequence of the first law.

so the fly will go to the back of the train when it accelerate? So how is it possible to see a fly flying around in a train.

 

[PhaseShifter]

So how is it possible to see a fly flying around in a train.

On a trip of any significant length, how much time does the train actually spend accelerating?

 

[Doc Al]

its just like a fly in a train

So what supports the fly? The air, of course.

so the fly will go to the back of the train when it accelerate? So how is it possible to see a fly flying around in a train.

In order for the fly to accelerate, a net force must act on it. (It's got to push against the air.) If the train lurches forward, the fly will appear to be pushed toward the rear of the train unless it compensates. (Which it can easily do. Flys zoom all over the place creating greater accelerations than you are likely to experience on a train.) Once the train stops accelerating, everything is back to normal.

 

[semc]

So what supports the fly? The air, of course.

Sorry i don't quite get it. So what if the air support the fly? It has got the same speed as the train just like us when we are inside a train?

Wow so the fly doesn't have to fly at the same speed as the train to appear stationary?

 

[Doc Al]

Sorry i don't quite get it. So what if the air support the fly?

Something must exert a force on the fly to accelerate it.

It has got the same speed as the train just like us when we are inside a train?

Not sure what you mean. Flys buzz around.

Wow so the fly doesn't have to fly at the same speed as the train to appear stationary?

What do you mean by "fly" at the same speed as the train? To appear stationary within the train, it must have the same speed as the train.