Geo Rotation

[Erica]

I saw a great video on YouTube on magnetic levitation.

 

 

The spinner remains suspended in the air above the magnet.

 

If the earth is rotating at 460 m/s why doesn't the spinner fall to the ground? Surely the magnet would move away due to the rotation of the earth, thus the spinner would eventually fall.

 

As far as I can tell there is only gravity and the magnetic force acting on the spinner no lateral forces.

[swansont]

Everything is moving, though, so that motion can be ignored in most cases. If the system is inertial to a very good approximation, it's just like being at rest.

 

For the motion to matter, you would have to be looking at something that depends on the fact that the earth is rotating, such as a Foucault pendulum.

[Erica]

Everything is moving, though, so that motion can be ignored in most cases. If the system is inertial to a very good approximation, it's just like being at rest.

 

How long would it take for it to lose the inertial momentum? Or drop to a sufficient level such that the speed of the earth is greater?

 

I'm out of my depth here.

[swansont]

How long would it take for it to lose the inertial momentum? Or drop to a sufficient level such that the speed of the earth is greater?

 

I'm out of my depth here.

 

If the object were free to move, then being a distance d above the surface means it moves an additional pi*d*cos(latitude) per day. IOW, for 2 cm height, at the equator, it would lag by 6.3 cm per day (7.3 x 10^-7 m/s) if they started at the same speed. But it's moving that much faster to begin with, so there would end up being no lag at all.