> Thanks for reply.
> I have googled it, so I said "an effective..."
> I want to understand how Velocity works in details
> because of I will extend an already existing project
> based on velocity.
> Thanks.
That's a physics question, not a java question. Here's the search I did: http://www.google.com/search?q=velocity+physics+tutorial The results seemed pretty good to me. If they aren't "effective" enough for you, why don't you explain what's so "ineffective" about them.