Behaviour of a Ball (Bouncing and Spinning)

Jonas Huckestein · science forum beginner Joined: 20 Jul 2006 Posts: 1

Hello,

I am currently programming a program in which I need to simulate the
behaviour of a ball in three dimensions. My ball has the following
properties:
- position
- direction
- velocity
- acceleration
- spin-axis
- spin-rpm (number of rounds per minute the ball turns around the
spin-axis)

Now I basically need to simulate two things:

1. How do the properties change when the Ball bounces against a moving
"paddle", meaning a rectangular object with a flat surface moving on a
plane along the x- and y-axis of my simulation (for sake of simplicity --
the z-axis is the depth, also that is not important)? The only interesting
properties of the paddle are the direction and the speed of movement. I
figured there are two different types of collison. Firstly, if the ball's
center strikes somewhere on the paddle and secondly, which is more
complicated when the ball hits the edge of the paddle. How can I calculate
the new properties of the ball? Would it be useful to include a deformation
of the ball into my simulation (which I would rather not do, though)? I do
not need to know what happens to the paddle during the collision, since it
will travel into its original direction after the impact. Possibly this
means, that it has an infinity mass or something. Speaking of mass, do I
also need to include a weight-property of the ball into my simulation?
(coming to think about it, I think I do)

2. How do I calculate the movement of the ball in the air? I do not need to
deterministically calculate the entire path, all I need to do is update the
ball's properties 100 times per second, as the program runs at a logic
framerate of 100 fps. So basically wihtout spin and acceleration I would
simply do something like add the directional vector multiplied by the speed
to the position. I understand that the movement is closely related to a
certain Magnus-Force which I don't really understand.

For a better understanding of the situation, here's a short description of
the context. The ball is moving inside a cuboid which has two missing
sides. Along these sides we have one small paddle each which moves around
in its missing rectangle. There is no gravity in the simulation. Yet there
has to be some sort of air around to enable the Magnus-Effect (if I have
understood that correctly).

I hope someone can explain one of my questions, since I am not a physicist.
I hope you are able to understand what I mean, since English is not my
native language. Please do correct me if I have used non-physical
expressions, as I don't know any English physics.

Thanks in advance and greetings from Germany,

Jonas

--
Jonas Huckestein

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