Elastic Collisions of Two Spheres

In an elastic collision, both momentum and kinetic energy are conserved. This Demonstration models collisions between two hard spheres of equal density. You can vary the relative mass and the impact parameter , the distance of closest approach of the centers if the spheres are undeflected. For a head-on collision, . You can observe the collision in slow motion in either the laboratory or the center-of-mass frame of reference. The spheres leave dotted contrails to help you trace their trajectories.


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Snapshot 1: The simplest case is a head-on collision between identical spheres: they simply exchange velocities.
Snapshot 2: The trajectories of two identical spheres in any angular collision are exactly perpendicular.
Snapshot 3: A lighter sphere gets the worst of a collision.
Snapshot 4: Here is the same collision viewed in center-of mass frame.
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