Free Fall XY

Free Fall XY extends the Free Fall model of a ball bouncing on a table top to include motion in the x (horizontal) direction.  The model includes a trace that shows the ball's trajectory as well as a more sophisticated collision algorithm that takes into account the finite width of the table top.  Newton's second law F = ma  is a vector equation and  it must be satisfied in both the horizontal and vertical direction.

Fx = max
Fy = may .

Because the force in the x (horizontal) direction is zero, the associated acceleration ax is also zero and the velocity vx is constant.  As in the Free Fall model, an impulsive normal force acting perpendicular to the table top reverses the ball's velocity upon collision.  The table top corner is treated as a special case.  The impulsive force from a corner collision is applied along a line from the corner toward the ball center.