Re: How do you bounce a ball and catch it on a train?

Hi Rebecca
Let's consider your train scenario.  First consider a train that is not 
moving.  If a passenger on the train bounces a ball, both the passenger 
and a person on the platform with see the ball go down hit the floor and 
bounce up, roughly in a straight line.  That is easy enough to picture, 
now consider when the train is moving say at 5 meters a second to the 
right.  Everything else inside the train is also moving at this speed, the 
chairs the passengers, the ball and the floor.  Therefore when the ball is 
dropped it is not only travelling down due to gravity but to the right at 
5 m/s.  As the passenger is also moving at this speed it appears to them 
that the ball has simply bounced down and then up in a straight line.  
However a person watching the ball from the platform will see the ball 
travel in a parabola (arc) between bounce and catch as they are observing 
the balls motion in reference to themselves, that is the earth rather than 
the train.  As a result your reference frame, or perspective, whether you 
are moving with the ball or not, produce a different perception of the 
same event.

I hope this answers your question.

Katie Pilypas