This Demonstration illustrates direct linear impact of two disks and the relationship between their masses, velocities, and the coefficient of elasticity. The velocity vectors of disks A and B are shown before and after impact by red and green vectors, respectively. Interesting variations to try are (1) A and B with the same mass and equal (but opposite) velocities, (2) disk B with zero initial velocity, and (3) coefficient of elasticity equal to 0.