Foucault pendulum string medium

[adam.kumayl]

This question is literally driving me crazy. How does the String or rope or whatever is used in a Foucault pendulum not twist with the rotation of the Earth (because the rope is attached to bases that are attached to the ground).

Actually if the bases are attached to the ground, that should be the ENTIRE thing is rotating so how are we able to see the effect?

please if you're going to explain it dumb it down to the most reduced form of an explanation visually because this problem is on my nerves. Thank you in advance!

 

[A.T.]

This question is literally driving me crazy. How does the String or rope or whatever is used in a Foucault pendulum not twist with the rotation of the Earth (because the rope is attached to bases that are attached to the ground).

What should prevent it from untwisting? With rigid Foucault pendulums you obviously need a bearing in the attachment, that gives the vertical axis free.

 

[adam.kumayl]

I'm sorry I'm not quite clear on the things you described. If it twists it should mess up the motion of the swing, we know that it DOESNt twist..Why doesn't the rope twist?

 

[Cleonis]

This question is literally driving me crazy. How does the String or rope or whatever is used in a Foucault pendulum not twist with the rotation of the Earth

To think about that case start with a simplified setup, then add features back to it.

In this case start with a pendulum at one of the Earth's poles, say, the South pole. Also consider first a non-swinging pendulum.

So you have that pendulum bob, suspended above the south pole. That pendulum bob is co-rotating with the Earth. The wire of the non-swinging pendulum will not twist/untwist because the bob is rotating around its own axis, co-rotating with the Earth.

Next step: such a pendulum on any latitude. Let's call that a 'latitudinal pendulum'. Such a pendulum is circumnavigating the Earth. The thing is: just as the polar pendulum bob is rotating on it's own axis, the latitudinal pendulum is rotating on it's own axis. So just as the polar pendulum bob will not twist the wire the latitudinal pendulum will not twist the wire.

Adding swing makes no difference either, not to the polar pendulum and not to the latitudinal pendulum.
(As many have pointed out in earlier threads: on a scientific station located right at the south pole, in the winter of 2001, three guys have actually rigged a foucault setup, in a high staircase. Allan Baker recounts it was tough going; that staircase was unheated.)

 

[PJC01]

I can understand your frustration with this concept. The key to understanding how the string or rope in a Foucault pendulum does not twist with the Earth's rotation lies in the principle of inertia.

Inertia is the tendency of an object to resist changes in its motion. In the case of the Foucault pendulum, the rope is attached to a base that is anchored to the ground. This means that the base and the ground are essentially acting as one solid object.

Now, imagine the pendulum is set into motion. As it swings back and forth, it maintains its direction and plane of motion due to inertia. This means that the pendulum will continue to swing in the same direction even as the Earth rotates beneath it.

Think of it like this - imagine you are on a moving train and you throw a ball straight up in the air. From your perspective, the ball goes straight up and down. But from an outsider's perspective, the ball actually travels in a curved path due to the train's motion. This is similar to what is happening with the Foucault pendulum.

As for why we can still see the effect of the pendulum, it is because the Earth's rotation is very slow compared to the pendulum's swing. This allows the pendulum to complete multiple swings before the Earth rotates enough to significantly affect its motion.

I hope this explanation helps to alleviate your frustration and make the concept clearer. Remember, the key is to think about inertia and how the pendulum's motion is independent of the Earth's rotation.