public float getFriction() {
        return rBody.getFriction();
    }
Set the local gravity of this PhysicsRigidBody<br>
Set this after adding the node to the PhysicsSpace,
the PhysicsSpace assigns its current gravity to the physics node when it's added.
@param gravity the gravity vector to set
jme3-jbullet/src/main/java/com/jme3/bullet/objects/PhysicsRigidBody.java