All objects in a PhysicsBoard are handled by the physic-engine
Each physics-object can have the following properties:
object_name.physics.mass (int; 1) The mass of the token. Default: 1
object_name.physics.gravity (bool; true): Should the token follow the laws of physics?
object_name.physics.friction (int; 10): When surfaces are in contact to each other, the driction removes the kinetic energy.
object_name.physics.elasticity (int; 0.5): How much should other objects bounce off the token?