Rigid Body Physics modeling deals with objects as solid, unchangeable sets of mass having a velocity that can be connected together via various joint types that allow one body's motion to affect another.
These examples support the X3D Rigid Body Physics component for simple kinematics, first implemented by Xj3D.
Warning: the Rigid Body Physics component in not widely supported and these examples are insufficiently tested. Further work is welcome.
Of related interest: Distributed Interactive Simulation (DIS) examples.
This viewpoint slideshow is online at https://www.web3d.org/x3d/content/examples/Basic/RigidBodyPhysics/viewpointSlideshow.html
Viewpoint image version history at https://sourceforge.net/p/x3d/code/HEAD/tree/www.web3d.org/x3d/content/examples/Basic/RigidBodyPhysics/_viewpoints