will a suspended magnet rotate 1/day?

[Sigene]

I heard something of a lodestone (magnetic rock) shaped in a sphere will rotate once per day…mimicking the earth.

So I have a disk magnet with a small nail attached that is magnetically suspended from a knife blade. Will this magnet rotate spontaneously?

I set it up an hour ago and it doesn’t seem to be moving…but I could be too early. I’m impatient.

If not; is there some other set up with a magnet that I can use to mark the passage of time.

(That pendulum thingy I see in the museums won’t work for me…I don’t have the space.)

[Shamozzle]

It’s position is static within the earth’s magnetic field, no?

[Joey_P]

It should rotate, if set up properly, I could see it rotating toward magnetic North (like a compass) but once it’s there, I don’t see why it would continue to rotate.
I think you’re might be mis-understanding why you think it might rotate once per day. For it to rotate once per day, you would have to find a way to get it to always point at the sun.

[DrFidelius]

Of course it rotates once a day. Unfortunately, everything around it is also rotating at the same rate, so you see no change in its orientation relative to your frame of reference.

Foucault’s Pendulum seems to rotate because it is swinging in a straigt line, while the Earth rotates underneath it.

[Sigene]

What is this guy talking about then (at 2:30)

- YouTube

Could James Burke be (gasp) wrong? If anything what he said is confusing.

[Chronos]

Foucault’s Pendulum seems to rotate because it is swinging in a straigt line, while the Earth rotates underneath it.

This is only the case at the poles. Anywhere else on Earth, it’s more complicated, and it will take longer than a day to make a full rotation relative to its mounting.

[TimeWinder]

@Sigene

What is this guy talking about then (at 2:30)

http://www.youtube.com/watch?v=wEqOnEOUlqs&feature=related

Could James Burke be (gasp) wrong? If anything what he said is confusing.

Good question: He certainly seems to be saying that his earth-equivalent magnet will turn once in a day; even moves his finger to show the path.

But notice that his magnet isn’t suspended like a compass needle hanging from a wire. Instead, he seems to have suspended the magnet through it’s poles: i.e. the magnetic axis is held in position (presumably not aligned with the earth’s magnetic poles), and the rest of the magnet is rotating around that.

Which is very nice and all…but I don’t know why it would do that, either. The magnet’s position isn’t changing with respect to the Earth’s magnetic field. I’d like to know what Mr. Connections means here, too – it was obviously just a throwaway line, but it doesn’t make sense to me, either.

[Squink]

Foucault Pendulums positioned at the North and South Pole would swing completely around in twenty-four hours, but clockwise for the north and counterclockwise for the south. On the equator, the pendulum simply swings back and forth like a grandfather clock. At 41.79 degrees latitude, Foucault’s equation accurately predicts that the museum’s pendulum swings clockwise 239.9 degrees in one day.

On the lower level of Chicago’s Museum of Science and Industry, next to the Brain Food Court, is a blue stairwell with a large pendulum suspended from its lofty ceiling.

[Sigene]

@TimeWinder

. Instead, he seems to have suspended the magnet through it’s poles: i.e. the magnetic axis is held in position (presumably not aligned with the earth’s magnetic poles), and the rest of the magnet is rotating around that.

This is how I have my magnet suspended. The poles are normal to the earths surface. It’s been over 6 hours now and no movement.

Dammit, it would have made a really cool clock.

Maybe if I spin it the poles will wobble (is it procession?) once per day.

[njtt]

Foucault’s pendulum has nothing to do with magnetism.

[Richard_Pearse]

A gyro will do the same sort of thing as the pendulum. Gyros are used in aircraft heading instruments. Is it possible that someone is getting confused between gyro stabilised heading and magnetic heading?

[si_blakely]

@TimeWinder

Good question: He certainly seems to be saying that his earth-equivalent magnet will turn once in a day; even moves his finger to show the path.

But notice that his magnet isn’t suspended like a compass needle hanging from a wire. Instead, he seems to have suspended the magnet through it’s poles: i.e. the magnetic axis is held in position (presumably not aligned with the earth’s magnetic poles), and the rest of the magnet is rotating around that.

Which is very nice and all…but I don’t know why it would do that, either. The magnet’s position isn’t changing with respect to the Earth’s magnetic field. I’d like to know what Mr. Connections means here, too – it was obviously just a throwaway line, but it doesn’t make sense to me, either.

It was fairly clear to me that James Burke was presenting William Gilbert’s view, without pointing out that it is experimentally false, and that Gilbert actually knew that it was false. From here

@Cambridge Scientific Minds pg 12

In Book VI Gilbert marshalled evidence that magnetism was the motive force of the Earth’s Copernican motions. He may have been inspired by the thirteenth-century writer Petrus Peregrinus, who claimed that a spherical magnet suspended from it’s pole rotated every twenty-four hours. Gilbert typically tested the claim and rejected it, at least for ordinary magnets. But for the ‘Prime Magnet’, i.e. the Earth, Gilbert asserted that its soul-like magnetic power did indeed imbue it with a fifth magnetic power, that of rotation.

Gilbert did a number of truly scientific experiments with magnets, and proposed information that explained how compasses worked (including magnetic variation/inclination, the magnetic nature of the earth and poles, and local variation in magnetic fields). However, he was not a true scientist and his experiments and results were coloured by his world view.

Si