Hi everyone, I am making a project involving shooting a tennis-sized ball by means of an automated mechanism. I have two horizontal wheels which are at the same height from the ground, and are spinning in opposite directions via motors. There is a space between them, a bit smaller than the ball which is to be pushed through them. The mechanism works like this: the wheels are spinning at a very high speed (around 3000RPM), and when the ball is pushed between them, it will be squeezed and will shoot out at high speed. Now here's the problem: I need to choose the material of the wheels and the width of the shafts spinning them so as to minimize the amount of lateral displacement caused when the ball is squeezed through so the mechanism doesn't fall apart. The ball is quite hard (in fact, it is a cricket ball). In order to do so, I will need to know the force exerted by the ball on the wheels when they attempt to squeeze it, and will then make sure the materials are chosen to withstand this force. Can anyone give me a push in the right direction regarding the calculations involved? I need to work out the aforementioned force. I know it is not a simple calculation by any means, so any hints will be appreciated.