I found this tip in http://unity3d.com/support/documentation/Manual/Physics.html But I would like to know why? What sort of problems can this create?
asked May 04 '11 at 09:59 AM
A rigidbody component controls the GameObject it's attached to. The velocity get's calculated in worldspace. If you parent a rigidbody to another, the child will get additional "forces" (actually the gameobject will move along with the parent, so no real forces) that will make the child do crazy things. A rigidbody represents one single physic object. Parent-child relationship doesn't work here. If you want two rigidbodies to be bound together, use joints.
answered May 04 '11 at 11:55 AM