a 3-dimensional "coriolis" effect (banging into the side of the hole that is ipsilateral to the direction of your rotational momentum) is something I did not think of, thank you for mentioning that, I would think it can be avoided if the hole passes directly through the axis of rotation, but just the same, we can imagine an ideal planet that does not rotate or have air around it.You're right. Taking in to account velocity, and cancelling out the Coriolis Effect, which would keep you from arriving to the center of earth in the first place, you'd keep shooting from one end of the tunnel to the other end. If earth was hollow, or you arrived at the center with zero velocity, you'd float.


