Foucault pendulum string medium

In summary, the Foucault pendulum does not twist because the wire is not attached to the Earth's rotation. Instead, the wire is attached to a stationary base, which allows it to remain stationary while the Earth rotates around it.
  • #1
adam.kumayl
6
0
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!
 
Physics news on Phys.org
  • #2
adam.kumayl said:
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.
 
  • Like
Likes FPdmsssdeun
  • #3
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?
 
  • #4
adam.kumayl said:
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.)
 
Last edited:
  • Like
Likes FPdmsssdeun
  • #5


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.
 

What is a Foucault Pendulum?

A Foucault pendulum is a device used to demonstrate the rotation of the Earth. It consists of a long, heavy pendulum suspended from a ceiling that swings back and forth in a fixed plane. As the Earth rotates underneath it, the pendulum appears to rotate in a clockwise or counterclockwise direction, depending on the latitude of the pendulum.

How does a Foucault Pendulum work?

The rotation of the Earth causes the plane of the pendulum's swing to rotate, due to the Coriolis effect. This effect is a result of the Earth's rotation and the pendulum's inertia, causing the pendulum to appear to change direction over time. The rotation of the pendulum is directly related to the latitude of the pendulum's location, with no rotation occurring at the equator and the maximum rotation occurring at the poles.

What is the string medium of a Foucault Pendulum?

The "string medium" of a Foucault Pendulum refers to the material used to suspend the pendulum from the ceiling. This can be any type of string or wire, as long as it is strong enough to support the weight of the pendulum. Some common materials used are nylon, steel, or even piano wire.

Can a Foucault Pendulum be affected by external forces?

Yes, there are several external factors that can affect the motion of a Foucault Pendulum. These include air resistance, vibrations, and changes in temperature or humidity. These external forces can cause the pendulum to deviate from its expected path and may need to be accounted for in experiments or demonstrations.

What is the practical application of a Foucault Pendulum?

While the primary purpose of a Foucault Pendulum is to demonstrate the Earth's rotation, it also has practical applications in scientific research. For example, it can be used to study the effects of the Earth's rotation on large objects or to determine the latitude of a location. It is also used in some navigational devices, such as gyrocompasses, which rely on the Earth's rotation to function.

Similar threads

Replies
10
Views
898
Replies
13
Views
6K
  • Introductory Physics Homework Help
Replies
9
Views
636
  • Mechanics
Replies
10
Views
2K
Replies
5
Views
2K
Replies
2
Views
3K
Replies
15
Views
2K
Replies
12
Views
3K
Replies
49
Views
2K
Replies
2
Views
5K
Back
Top