A message about the Foucault pendulum. St. Isaac's Cathedral

Gorbatsevich S.A. Foucault pendulum. Historical, illustrative and demonstration material for the topic “Mechanical vibrations and waves” // Physics: problems of laying out. - 2010. - No. 1. - P. 58-61. - Author's version.

By special agreement with the editors of the FPV journal and the author

Foucault pendulum

A Foucault pendulum is a pendulum used to experimentally demonstrate the Earth's daily rotation.

Foucault, Jean Bernard Leon.

On January 3, 1851, Jean Bernard Leon Foucault conducted a successful experiment with a pendulum, which later received his name. The Paris Pantheon was chosen for the experiment; a pendulum thread 67 meters long could be strengthened there. A cast iron ball weighing 28 kilograms was attached to the end of a steel wire thread. Before launch, the ball was moved to the side and tied with a thin string encircling the ball along the equator. A round platform was made under the pendulum, along the edge of which a roll of sand was poured. One full swing of the pendulum lasted 16.4 seconds, and with each swing, the tip attached under the pendulum ball drew a new line in the sand, clearly showing the rotation of the platform beneath it, and, consequently, the entire Earth.

The experiment is based on the property of a pendulum to maintain its plane of oscillation regardless of the rotation of the support to which the pendulum is suspended. An observer rotating with the Earth sees a gradual change in the direction of the pendulum's swing relative to surrounding earthly objects.

When implementing an experiment with a Foucault pendulum in practice, it is important to eliminate the reasons that interfere with its free swing. For this purpose, they make it very long, with a heavy and symmetrical load at the end. The pendulum should have the same ability to swing in all directions and be well protected from the wind. The pendulum is mounted either on a cardan joint or on a horizontal ball bearing that rotates along with the swing plane of the pendulum. Starting the pendulum without a side push is of great importance for the results of the experiment. At the first public demonstration of Foucault’s experiment in the Pantheon, the pendulum was tied with twine precisely for this purpose. When the pendulum, after being tied, came to a state of complete rest, the rope was burned, and it began to move.

Since the pendulum in the Pantheon completed one complete swing in 16.4 s, it soon became clear that the plane of the pendulum was rotating clockwise relative to the floor. With each subsequent swing, the metal tip swept away sand approximately 3 mm from the previous place. In an hour, the swing plane rotated more than 11° clockwise, in about 32 hours it made a full revolution and returned to its previous position. This impressive display had the audience downright hysterical; it seemed to them that they could feel the rotation of the Earth under their feet.

To find out why a pendulum behaves this way, consider a ring of sand. The northern point of the ring is 3 m from the center, and given that the Pantheon is at 48°51" north latitude, this part of the ring is 2.3 m closer to the earth's axis than the center. Therefore, when the Earth rotates 360° during For 24 hours, the northern edge of the ring will move in a circle of smaller radius than the center, and will travel 14.42 m less in a day. Therefore, the difference in the speeds of these points is 1 cm/min. In the same way, the southern edge of the ring moves 14.42 m. per day, or 1 cm/min, faster than the center of the ring. Thanks to this speed difference, the line connecting the northern and southern points of the ring always remains directed from north to south.

At the earth's equator, the northern and southern ends of such a small space would be at the same distance from the earth's axis and, therefore, move at the same speed. Therefore, the surface of the Earth would not rotate around a vertical pillar standing at the equator, and the Foucault pendulum would swing along the same line. The rotation speed of the swing plane would be zero, and the time for a complete revolution would be infinitely long. If the pendulum were installed exactly on one of the geographic poles, it would turn out that the swing plane rotates exactly 15° every hour and makes a full rotation of 360° in 24 hours. (The surface of the Earth rotates 360° per day around the earth's axis) .

At all other latitudes, the Foucault effect manifests itself to varying degrees, with its effect becoming more pronounced as one approaches the poles.

Paris. Pantheon. Foucault pendulum

The longest thread - 98 meters - was at the Foucault pendulum, located in St. Isaac's Cathedral in St. Petersburg. The pendulum was removed in 1992 as it did not correspond to the purpose of the building.

Now in the North-West of Russia there is only one Foucault pendulum - in the St. Petersburg Planetarium. The length of its thread is small - about 8 meters, but this does not reduce the degree of clarity. This Planetarium exhibit is of constant interest to visitors of all ages.

The Foucault Pendulum, currently housed in the visitors' lobby of the United Nations General Assembly Building in New York, is a gift from the Government of the Netherlands.

This pendulum is a 200-pound gold-plated ball, 12 inches in diameter, partially filled with copper and suspended from a stainless steel wire from the ceiling above the ceremonial staircase, 75 feet from the floor. The upper end of the wire is secured with a universal joint, which allows the pendulum to swing freely in any vertical plane. Each time the ball oscillates, it passes over a raised metal ring containing an electromagnet, causing an electric current to be induced in the copper inside the ball. This interaction provides the necessary energy to overcome friction and air resistance and ensures that the pendulum swings evenly.

In September 2004, at the Belarusian State Pedagogical University named after Tank, the opening of a unique structure for the science and culture of our country took place - the Foucault pendulum. The celebration was attended by Metropolitan Philaret of Minsk and Slutsk, Patriarchal Exarch of All Belarus, university teachers, physicists, and students.

The Foucault pendulum is a tetrahedral glass pyramid 7.5 meters high, inside of which a ball weighing 27 kilograms is suspended on a steel wire. The special magnet that sets the pendulum in motion was made in Kaluga. The full amplitude of vibration is 2.5 meters.

An observer located on the Earth and rotating with it will notice that the plane of swing of the pendulum slowly turns relative to the Earth in the direction opposite to the rotation of our planet. At the latitude of Minsk, during a sidereal day, the pendulum describes an arc of 290 degrees, that is, it moves by 12 degrees per hour (at the poles, the swing plane of the pendulum makes a full revolution every day). The Foucault pendulum at the Minsk Pedagogical University is the first in our country and the third in the CIS (there are also such structures in the planetariums of St. Petersburg and Smolensk). There are about twenty such devices in the world, including in the USA, France, Romania, Australia, and Kuwait.

Is it possible to make such a structure on your own, using simple, accessible props, in a small laboratory or at home?

Foucault pendulum models

I offer two options: mechanical and electromechanical models of the Foucault pendulum.

Mechanical model

To demonstrate the experience, the following materials are required:

cork – 1 pc.;
pin – 2 pcs.;
fork – 3 pcs.;
plate – 1 pc.;
cargo (apple or potato) – 1 pc.;
thread;
salt.

Manufacturing:

use a cork and forks to build a pyramid;
Using thread and pins, secure the weight to the bottom of the cork;
place the pyramid on a plate, while the bottom pin should not touch the bottom;
Sprinkle salt along the edge of the bottom of the plate in a mound-shaped circle.

FOUCAULT PENDULUM, a device that clearly demonstrates the rotation of the Earth. Its invention is attributed to J. Foucault (1819–1868). At first, the experiment was carried out in a narrow circle, but L. Bonaparte (who later became Napoleon III, the French emperor) was so interested that he invited Foucault to repeat it publicly on a grand scale under the dome of the Pantheon in Paris. This public demonstration, organized in 1851, is commonly called the Foucault experiment.

Under the dome of the building, Foucault suspended a metal ball weighing 28 kg on a steel wire 67 m long. Unlike a clock pendulum, which can only swing in one plane, the Foucault pendulum had the upper end of the wire fixed in such a way that it could swing equally freely in all directions. A circular fence with a radius of 6 m was made under the pendulum with the center directly under the suspension point. Sand was poured onto the fence so that with each swing, a metal tip attached under the pendulum ball could sweep it away in its path. To ensure the launch of the pendulum without a side push, it was taken to the side and tied with a rope. After the pendulum, after being tied, came to a state of complete rest, the rope was burned and the pendulum began to move.

A pendulum of this length makes one complete swing in 16.4 s, and it soon became clear that the swing plane of the pendulum rotates clockwise relative to the floor. With each subsequent swing, the metal tip swept away sand approximately 3 mm from the previous place. In an hour, the swing plane rotated by more than 11°, and in about 32 hours it made a full revolution and returned to its previous position. This impressive display had the audience downright hysterical; it seemed to them that they could feel the rotation of the Earth under their feet.

To find out why a pendulum behaves this way, consider a ring of sand. The northern point of the ring is 3 m from the center, and given that the Pantheon is located at 48°51º north latitude, this part of the ring is 2.3 m closer to the earth's axis than the center. Therefore, when the Earth rotates 360° within 24 hours, the northern edge of the ring will move in a circle of smaller radius than the center, and will travel 14.42 m less per day. Therefore, the difference in speed between these points is 1 cm/min. Likewise, the southern edge of the ring moves 14.42 m per day, or 1 cm/min, faster than the center of the ring. Thanks to this speed difference, the line connecting the northern and southern points of the ring always remains directed from north to south.

: under the dome of the Pantheon, he suspended a metal ball weighing 28 kg with a point attached to it on a steel wire 67 m long, the pendulum mount allowed it to oscillate freely in all directions, a circular fence with a diameter of 6 meters was made under the attachment point, sand was poured along the edge of the fence path in such a way that the pendulum, in its movement, can draw marks in the sand when crossing it. To avoid a side push when starting the pendulum, it was taken to the side and tied with a rope, after which the rope was burned.

The period of oscillation of the pendulum with such a suspension length was 16.4 seconds, with each oscillation the deviation from the previous intersection of the sand path was ~3 mm, in an hour the plane of oscillation of the pendulum rotated more than 11° clockwise, that is, in about 32 hours it completed a full revolution and returned to its previous position.

Physics of experiment

In St. Isaac's Cathedral in Leningrad, Foucault's pendulum was launched on the night of April 11-12, 1931. Then it was called the triumph of science over religion. However, church representatives noted that this experience in no way refutes the dogma of the existence of God. The curator of the exhibition at St. Isaac's Cathedral, Sergei Okunev, commented on this:

Notes

Wikimedia Foundation. 2010.

See what “Foucault Pendulum” is in other dictionaries:

A FOUCAULT PENDULUM, a heavy metal spherical (or disk-shaped) object suspended from a long thin wire, was first used by Jean FOUCAULT to demonstrate the rotation of the Earth. Since the Earth rotates around its axis, the plane... ...

A model of a Foucault pendulum located in the southern hemisphere of the Earth. A Foucault pendulum is a pendulum used to experimentally demonstrate the daily rotation of the Earth. Contents 1 Foucault's experiment ... Wikipedia

A device that clearly demonstrates the rotation of the Earth. Its invention is attributed to J. Foucault (1819 1868). At first, the experiment was carried out in a narrow circle, but L. Bonaparte (who later became Napoleon III, the French emperor) became so interested that he... ... Collier's Encyclopedia

Foucault pendulum- Fuko švytuoklė statusas T sritis fizika atitikmenys: engl. Foucault pendulum vok. Foucaultsches Pendel, n rus. Foucault pendulum, m pranc. pendule de Foucault, m … Fizikos terminų žodynas

Foucault Pendulum: A Foucault pendulum is a pendulum used to experimentally demonstrate the daily rotation of the Earth. Foucault's Pendulum is the second novel by Umberto Eco (1988) ... Wikipedia

For the mathematical pendulum, see Foucault pendulum. Foucault's pendulum Il pendolo di Foucault ... Wikipedia

PENDULUM, any body suspended at any point so that it oscillates, describing an arc of a circle. A simple, or mathematical, pendulum consists of a small, heavy load suspended on a thread or on a light, rigid rod.… … Scientific and technical encyclopedic dictionary

FOUCAULT PENDULUM
a device that clearly demonstrates the rotation of the Earth. Its invention is attributed to J. Foucault (1819-1868). At first, the experiment was carried out in a narrow circle, but L. Bonaparte (who later became Napoleon III, the French emperor) was so interested that he invited Foucault to repeat it publicly on a grand scale under the dome of the Pantheon in Paris. This public demonstration, organized in 1851, is commonly called the Foucault experiment.

Under the dome of the building, Foucault suspended a metal ball weighing 28 kg on a steel wire 67 m long. Unlike a clock pendulum, which can only swing in one plane, the Foucault pendulum had the upper end of the wire fixed in such a way that it could swing equally freely in all directions. A circular fence with a radius of 6 m was made under the pendulum with the center directly under the suspension point. Sand was poured onto the fence so that with each swing, a metal tip attached under the pendulum ball could sweep it away in its path. To ensure the launch of the pendulum without a side push, it was taken to the side and tied with a rope. After the pendulum, after being tied, came to a state of complete rest, the rope was burned and the pendulum began to move. A pendulum of this length makes one complete swing in 16.4 s, and it soon became clear that the plane of swing of the pendulum rotates clockwise relative to the floor. With each subsequent swing, the metal tip swept away sand approximately 3 mm from the previous place. In an hour, the swing plane rotated by more than 11°, and in about 32 hours it made a full revolution and returned to its previous position. This impressive display had the audience downright hysterical; it seemed to them that they could feel the rotation of the Earth under their feet. To find out why a pendulum behaves this way, consider a ring of sand. The northern point of the ring is 3 m from the center, and given that the Pantheon is at 48°51" north latitude, this part of the ring is 2.3 m closer to the earth's axis than the center. Therefore, when the Earth rotates 360° during For 24 hours, the northern edge of the ring will move in a circle of smaller radius than the center, and in a day it will travel 14.42 m less. Therefore, the difference in the speeds of these points is 1 cm/min. In the same way, the southern edge of the ring moves by 14.42 m. per day, or 1 cm/min, faster than the center of the ring. Thanks to this speed difference, the line connecting the northern and southern points of the ring always remains directed from north to south.

Collier's Encyclopedia. - Open Society. 2000 .

See what “FOUCAULT PENDULUM” is in other dictionaries:

For Umberto Eco's novel, see Foucault's Pendulum (novel). Model of a Foucault pendulum located in the southern hemisphere of the Earth. The trajectory of movement shown in the animation corresponds to the case when the pendulum is set in motion by a short push from ... ... Wikipedia

Foucault Pendulum: A Foucault pendulum is a pendulum used to experimentally demonstrate the daily rotation of the Earth. Foucault's Pendulum is the second novel by Umberto Eco (1988) ... Wikipedia

For the mathematical pendulum, see Foucault pendulum. Foucault's pendulum Il pendolo di Foucault ... Wikipedia

PENDULUM, pendulum, man. 1. A swinging heavy body on a rod attached at its upper end to a fixed point. Clock with a pendulum. Foucault pendulum. Physical pendulum (material, substantial, as opposed to mathematical; see below; physical). ||… … Ushakov's Explanatory Dictionary

- (Foucault) Jean Bernard Leon (1819 68), French physician and physicist, inventor of the GYROSCOPE. Using a pendulum (FOUCAULT PENDULUM) he proved that the Earth rotates around its axis. He developed a method for measuring the absolute speed of light and in 1850, measuring it... Scientific and technical encyclopedic dictionary

Kozhevnikov Evgeniy

The purpose of this work is to systematize the collected information and create a desktop demonstration installation of the Foucault pendulum.

Download:

Preview:

Regional competition for young researchers “Step into the future”

Topic: “Foucault Pendulum”

Completed:

Kozhevnikov Evgeniy Alexandrovich

9 "B" class MBOU "Secondary School No. 6"

Supervisor:

Davydova Irina Nikolaevna

Physics teacher MBOU "Secondary School No. 6"

Kolchugino

2012

Introduction 3

1.1. History of the creation of the Foucault pendulum 3

1.2. Foucault experiment 5

1.2.1. Experience Demonstration 5

1.2.2. Principle of operation of the pendulum 6

1.3. Biography of J.B.L. Foucault 6

1.4. Functioning Foucault pendulums 7

1.4.1. Operating pendulums in Russia and CIS countries 7

1.4.2. Operating pendulums in other countries 9

1.5. Interesting facts 11

2. Practical part 11

2.1. Pendulum models that you can make yourself 11

2.2. Pendulum model submitted to competition 13

Conclusion 14

References 15

Introduction

I learned about the existence of the Foucault pendulum from a 9th grade physics course (topic “Oscillations and Waves”). And then I watched the TV show “Galileo”, in which I saw a model of a pendulum made by the craftsmen of the program. And I decided to see if I could make such a working model myself. To do this, I collected and studied information from various sources: books, media, the Internet. The material was so interesting that I decided to systematize it and make a model myself.

The purpose of this work is to systematize the collected information and create a desktop demonstration installation of the pendulum. In the work, I presented material about the history of the creation of the pendulum, its first demonstration, the principle of operation, about various types of pendulum models created around the world, and I offer for the jury’s consideration a model of the pendulum made by myself.

I presented my work at a physics lesson in front of my classmates and at the school scientific and practical conference “Roads of Discovery” and was awarded a certificate for winning the “Applied Physics” category.

1.1 History of the creation of the Foucault pendulum

It turns out that not only Galileo loved to watch the swinging of the lamps in the cathedral. He passed this passion on to his student Vincenzo Viviani. In 1660, unlike Galileo, he drew attention to another feature of the oscillations of a pendulum on a long thread.

It turns out that the plane of their swing is constantly deviating, and always in the same direction - clockwise, if you look at the pendulum from top to bottom. And in 1664, a scientist from the city of Padua, Giovanni Poleni, connected this deviation with the rotation of the Earth - they say, the Earth rotates, but the plane of oscillation of the pendulum remains the same. So this is observed by people standing on Earth as a deviation of the swing plane of a pendulum.

But it turns out that this property of the pendulum was also known to the ubiquitous ancients. Indeed, the new is the well-forgotten old. This is what the Roman scientist Pliny the Elder, who lived in the 1st century, wrote about this in his “Natural History”. n. e.: “It is possible to arrange a compass without a magnet. To do this, you need to take a pendulum and make it swing in a certain direction. When the ship turns, the pendulum will maintain the direction given to it in its swings” (Fig. 1).

Rice. 1. Compass of Pliny the Elder on the ship Fig. 2. A rod clamped in a rotating

Patrone, does not change the plane of oscillation

It must be said that something in Pliny’s advice is questionable. First, Pliny could not have known about the compass; in Europe they learned about it much later, or at least they gave it that name. So much of what is attributed to Pliny could well have been contributed by the translator of his works from Latin in the 18th century. Secondly, it is impossible for the pendulum not to change the plane of its oscillations for so long; its suspension cannot be made ideal, and the air around it will cause interference. And thirdly, the rotation of the Earth will itself “deflect” the plane of oscillation of the pendulum, so that the ship “goes” in a circle. But one way or another, Pliny noticed that the pendulum retains the plane of its swing. And this property was brilliantly used by the French scientist Jean Bernard Leon Foucault (1819-1868), creating his famous pendulums. Since childhood, Foucault did not like to study; knowledge was difficult for him. But he had golden hands - he made toys, instruments, built a steam engine himself, and worked well on a lathe.

Foucault once noticed that if you clamp a long elastic steel rod in a machine chuck and make it vibrate (Fig. 2), the plane of oscillation will not change even with rapid rotation of the chuck. Having become interested in this phenomenon, Foucault first began to observe the behavior of the same rod in a rotating cartridge, and then, for convenience, decided to replace it with a pendulum.

Foucault conducted his first experiments with the pendulum in the cellar of his house in Paris. He attached a two-meter long hardened steel wire to the top of the cellar vault and suspended a five-kilogram brass ball from it. Taking the ball to the side, fixing it with a thread near one of the walls, Foucault burned the thread, giving the pendulum the opportunity to swing freely. And within half an hour he witnessed the rotation of the Earth.

This happened on January 8, 1851. And a few days later, Foucault repeated his experience at the Paris Observatory at the request of its director, the famous French scientist Arago. This time the length of the wire was already 11 m. And the deviation of the swing plane of the pendulum was even more noticeable.

Foucault's experience was talked about everywhere. Everyone wanted to see the rotation of the Earth with their own eyes. It got to the point that the President of France, Prince Louis Napoleon, decided to stage this experiment on a truly gigantic scale in order to demonstrate it publicly. Foucault was given the building of the Parisian Pantheon with a dome height of 83 m.

1.2. Foucault's experience

1.2.1. Demonstration of experience

The first public demonstration was carried out by Jean Foucault in 1851 in the Paris Pantheon (Fig. 3): under the dome of the Pantheon, he suspended a metal ball weighing 28 kg with a tip attached to it on a steel wire 67 m long; the pendulum mount allowed it to oscillate freely in all directions. directions, a circular fence with a diameter of 6 meters was made under the attachment point, a sand path was poured along the edge of the fence so that the pendulum, in its movement, could draw marks in the sand when crossing it. To avoid a side push when starting the pendulum, it was taken to the side and tied with a rope, after which the rope was burned.

1.2.2. The principle of operation of a pendulum

The principle of operation of the Foucault pendulum is that for each oscillation it deviates about a given trajectory due to the rotation of the Earth around its axis; this effect is most noticeable at the poles of the planet and is not noticeable at all at the equator. The larger the pendulum, the more noticeable the deflection effect. If a working pendulum, or rather the frame, begins to rotate, then the pendulum maintains its position, the same happens with the Earth, it rotates under the pendulum and it seems that the pendulum changes the direction of its oscillations, but in fact the pendulum simply maintains its position, and the Earth rotates. Since the pendulum is not rigidly connected to its frame, the frame rotates with the ground, and the pendulum maintains its position.

1.3. Biography of J.B.L. Foucault

FOUCAULT Jean Bernard Leon (1819-1868), French physicist, famous for his experiments in optics and mechanics. Born September 18, 1819 in Paris. He received his primary education at home. At the insistence of his father, he studied medicine, but became interested in experimental physics. From 1845 - scientific columnist for the newspaper "Journal of Discussions" ("Journal des Dbats"), from 1855 - employee of the Paris Observatory, from 1862 - member of the Bureau of Longitudes. Basic research relates to optics, mechanics, electromagnetism. Together with A. Fizeau, he conducted a number of optical studies, the most famous of which was the observation of the interference of light with a large path difference. In 1849-1850 he measured the speed of light in air and water using a rapidly rotating mirror. These comparative measurements finally confirmed the wave nature of light. In 1851, using a pendulum (Foucault pendulum), he demonstrated the rotation of the Earth around its axis. In 1852 he invented the gyroscope, now widely used in technology and navigation. In 1855 he discovered the heating of conductive material by eddy induction currents (Foucault currents) and proposed a way to reduce them. He developed a precision method for making mirrors for large reflectors and proposed using lighter and cheaper glass mirrors coated with a silver film instead of metal ones. Foucault's other inventions included an automatic light regulator for an arc lamp, a photometer, and a polarizing prism suitable for use in the UV region. Foucault was a member of the Royal Society of London, the Berlin Academy of Sciences; For scientific achievements he was awarded the Copley Medal.

1.4. Functioning Foucault pendulums

1.4.1. Operating pendulums in Russia and CIS countries

On February 24, 2011, the pendulum model appeared inKyiv. It is installed in (Fig. 4). The bronze ball weighs 43 kilograms, and the length of the thread is 22 meters. The Kiev Foucault pendulum is considered the largest in the CIS and one of the largest in Europe.

Opened on June 12, 2011Moscow Planetarium , where an operating Foucault pendulum with a thread length of 16 meters and a ball mass of 50 kilograms is installed (Fig. 5).

Opened on February 8, 2012Novosibirsk Astrophysical Complex , which includes a Foucault tower with a pendulum whose thread is 15 meters long.

A functioning Foucault pendulum with a thread length of 20 meters is available inSiberian Federal University (Krasnoyarsk ).

A working Foucault pendulum, weighing 12 kilograms and a thread length of 8.5 meters, is available in the Volgograd Planetarium.

A functioning Foucault pendulum is currently in the St. Petersburg Planetarium. The length of its thread is 8 meters.