Ball A moves along +x and strikes Ball B inside a box. The balls keep bouncing off each other and off the walls, and every collision is recorded. Tilt the sides of the box to turn the rectangle into a trapezoid or a triangle. The first ball-ball collision is explained step by step below.
0% is a head-on hit. Positive aims A above B's centre, negative below.
0° is vertical. A positive angle tilts that side inward, a negative angle tilts it outward. Tilt both sides inward far enough and they meet: the top disappears and the box becomes a triangle.
Every collision is recorded, ball with ball and ball with wall. A ball-ball collision never changes the total momentum. A wall collision does, because the wall pushes on the ball. Kinetic energy is only lost in inelastic collisions.
| # | Time (s) | Collision | e | A after (vx, vy) | B after (vx, vy) | Angles | Total KE after (J) | KE lost (J) |
|---|
Direction is measured from the +x axis. +y is up the screen. A "?" means: predict it first, then press Start.
Model: smooth balls with no friction and no spin, so no push acts along the tangent. Stuck balls move together without turning.
Total momentum is the same in every row. Only the kinetic energy changes, and the perfectly inelastic case always loses the most. When this run is not inelastic, the inelastic row uses e = 0.50.