Quiz Animation shows two particles undergoing a collision. The collision can be viewed in the center of mass reference frame or the laboratory frame. The initial velocity in the laboratory reference frame of the striking particle is adjustable. The impact parameter, the mass ratio and the coefficient of restitution can be adjusted using the appropriate sliders. The choice of the reference frame can be made from the drop down list of choices. The slider below the start button can be adjusted to run the animation frame by frame. The vector diagrams show the initial and final momentum vectors of the particles. The green vectors at the moment of contact indicate the direction of the forces acting on the individual particles.