Collisions with different masses
Get a new sphere that has a different mass from the two you used earlier.
Collide the new sphere with one of the spheres you used earlier. Again, try at least four different methods of collision, which may include the following:
Set the lighter sphere in place, and roll the heavier sphere toward it.
Set the heavier sphere in place, and roll the lighter sphere toward it.
Roll both spheres toward each other with the same initial speed.
