This applet features a theoretical Newton's cradle with five identical spheres free to move.
Drag the points below the spheres to determine the launch position of each sphere and then start the animation.
Comparison between a real Newton's cradle and its modeling in Geogebra
Presentation on how to model a simple Newton's Cradle (just one free sphere) in GeoGebra - the audio is in portuguese, but the video is subtitled