Yes, that's wrong. Centrifugal force is based on mass, not density. It is, actually. Correct! Which is why: 1) your theory doesn't work 2) why there is such a thing as a Clarke (geosynchronous) orbit Centrifugal force has nothing to do with "push." It has to do with "pull." An object will continue in a straight line if unconstrained. If you do constrain it (i.e. tie a string to it) it will still want to go in a straight line - but the string will apply a force that pulls it away from that straight line. Ideal Gas Law. Yes, without gravity the air around the planet would expand into space. (Indeed, would be thrown into space by the rotation of the Earth.) Through tension. Strictly speaking there is no such thing as centrifugal force. What people perceive as centrifugal force is the tension in the "string" that is continually deflecting the object from its desired path. In actuality if there was no gravity, the crust of the Earth would tend to continue to go in a straight line and go flying off into space, followed by most of the planet. The Earth has very little tensile strength. There won't be. About 17,600 MPH. Right, it provides a normal force only. Centrifugal force does not propagate through you. It merely reduces your weight. This does not come about because anything is pushing on you; this comes about because your body wants to continue in the same direction.