Two spheres a and b of masses m1 and m2 respectively collide
- Two spheres a and b of masses m1 and m2 respectively collide a is at rest
- Two spheres a and b of masses m1 and m2 respectively collide a is at rest initially
- Two similar spheres each of mass m and travelling with speed v
- Two similar spheres each of mass m and travelling with speed v are moving towards each other