This demonstration illustrates conservation of energy. The launcher stores potential energy, which is then converted to kinetic energy via the ball. The ball transfers this energy to the pendulum. By measuring the height reached by the pendulum, the potential energy can be calculated.
This demonstration illustrates how the ball has no “memory” of its initial direction of travel. We see the movement of the ball as it leaves the roller is perpendicular to the initial direction of travel.
This demonstration illustrates mechanical energy conservation in collisions. The number of balls that move is equal to the number of balls released, which shows the energy is conserved.