Suppose you have two balls where the first ball of mass M collides with the second ball of mass m and the second ball then collides with a wall and bounces back to hit the first ball. Collisions are assumed to be perfectly elastic. If the balls are of equal mass, then there are 3 collisions (two with each other plus one with the wall). If the mass of the first ball is 100 times the mass of the second ball, then there are 31 collisions. If you then make the mass of the first ball 100 times bigger than that, then you get 314 collisions. A Russian mathematician by the name of Gregory Galparin figured this out. The next figure is actually 3141 (digits of Pi!). This is a quick program to show the case where the mass of the first ball is 100 times the mass of the second. The physics formula to derive the motion uses only the coservation of momentum law and the conservation of energy law. Various exisiting I looked at various exisiting Scratch collison programs to get an idea of how to write a collision program and then tried my hand at this problem. The program needs some revision to handle the case where M=10000 and m=1 (314 collisions). Many people find it very interesting that Pi shows up in this way.
