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

If you are travelling in space, say on a train, how can you bounce a ball and 
be able to catch it as if when you are stationary?  To an observer on the 
ground it would appear that the ball travelled at the rate of the train's speed 
between bounce and catch.  How is this possible?  

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