Bren, Bren, Bren... Your understanding of physics in this case is lacking. Sure, a drop of liquid placed on a spinning disc will move away from the axis of rotation due to centripetal force. But that is because the drop of liquid is rotating along with the disc. The stylus does not experience the same force as the drop of liquid because it is attached to the tone arm, which rotates (across a very limited operational arc at very miniscule speeds) on a completely separate axis. The thing that keeps a stylus tracking properly is gravity, which holds the needle in the groove -- a groove that, I repeat, from the POV of the needle is nothing but a line that happens to slowly shift from right to left over time.
Let me put it another way. If you spin a bike tire and place your finger lightly on the tire's sidewall as it spins, do you feel a force perpendicular to the axis of rotation? No, but this is exactly what you're suggesting happens to the stylus.
Last edited by pmbuko; 06/14/06 07:14 AM.
