Grab RigidBodyPhysics from the downloads section.
RigidBodyPhysics is an implementation of the Rigid body physics component of the X3D specification. It includes nodes for creating scenes in which geometries acts like rigid bodies. That is objects which are solid, unchangeable sets of mass with velocity.
This is a bug fix release to address issues with compiling with gcc 3.1.1 and on 64 bits system. There are also some minor bug fixes included in the release. The release is binary compatible with RigidBodyPhysics 1.0.0.
RigidBodyPhysics uses a separate engine for calculating interaction between bodies. The physics engines to choose from are ODE, PhysX and Bullet. Full support is however only implemented for ODE in this version of RigidBodyPhysics.
For more information check out the RigidBodyPhysics entry in the H3D wiki at http://www.h3dapi.org/modules/mediawiki/index.php/RigidBodyPhysics.