I was recently reading about artificial gravity and generating it in space, especially by centripetal force using Stanford Tori and Bernal sphere (only Wikipedia and these to articles, but if anyone has any more resources, I would be glad to read them, I couldn't find anything else in my search). If an electrical engine would be in a rod (well, the shape, not actually a rod) and would rotate the tori around the rod (the 0G and 1G parts of the space shuttle), since the rod has smaller mass, what would happen? Would the rod spin counter-clockwise, the tori clockwise, or both in different senses of rotation? Is this any different from how they would behave on earth (under gravity). And would it change the situation, if the initial push was generated by thrusters on the circumference of the torus/sphere ?