This Demonstration shows the linear collision of two disks, with varying masses, velocities and coefficients of elasticity. The velocity vectors of the disks A and B are shown before and after impact by red and green arrows, respectively. The velocity is positive when left to right. The velocity versus time plot includes a collision region that is modeled using the tanh function to simulate real experiments. In all cases, the total momentum of the two disks is conserved.

Try these possible variations: 1. elastic collision (conservation of energy also applies), 2. inelastic collision and 3. completely inelastic collision (disks stick together after collision). Try to predict how the plot of velocity versus time should look; use the "velocity plot" button to test your prediction and also show numerical values of the final velocities (mouseover the graph).