Bouncing Mass-Spring System

This Demonstration shows the movements of two identical point masses (shown in red and blue). They are connected by a spring and under the simultaneous influence of gravity (resulting in a downward force), a soft rubber-like wall at the bottom (resulting in an upward force near the bottom), and air friction, as well as internal spring friction. The initial positions of the two points can be varied by clicking and dragging the red and blue crosses, × and ×.