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Foucault's Pendulum - Sixty Symbols
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- Опубликовано: 31 май 2010
- Foucault's Pendulum is a clever way of demonstrating the Earth's rotation - but it won't work at the equator! More physics at www.sixtysymbol...
With Roger Bowley
He is so engaged in his explanation about the mechanics of the pendulum, he forgets whish direction the Earth rotates , reminds me of my Professor. I love this channel.
Oh, he has a model @ 0:14 of rotating earth (mag levi) in the background to remind him :-)
@ 1:23 Ooops! where did it go?
He got it right, though.
@@ginnyjollykidd 4:39 Er, no. Watch again and visualize the sun rising in the east. His little globe would have to go the other way for that to happen.
I think you are both correct, the rotation of the pendulum depends on which hemisphere you are doing the experiment.
4:49 "And I can't remember which way it [the earth] rotates." The humility of a true scientist!
@Roman M. the whole point of the experiment is showing it DOES rotate lol. And it does. There are hundreds of these pendulums in museums, and it is just as he said.
@Roman M. deaf ears, and blind eyes, I see
@Roman M. true, you're the one calling people idiots first. Thanks for pointing it out.
"That was when I saw the Pendulum.
The sphere, hanging from a long wire set into the ceiling of the choir, swayed back and forth with isochronal majesty.
I knew -- but anyone could have sensed it in the magic of that serene breathing -- that the period was governed by the square root of the length of the wire and by pi, that number which, however irrational to sublunar minds, through a higher rationality binds the circumference and diameter of all possible circles. The time it took the sphere to swing from end to end was determined by an arcane conspiracy between the most timeless of measures: the singularity of the point of suspension, the duality of the plane's dimensions, the triadic beginning of pi, the secret quadratic nature of the root, and the unnumbered perfection of the circle itself."
Rest in peace Umberto Eco.
Heretics
okay I have an important question here. point at which the pendulum is connected ...is it not rotating along with the earth? did they use some kind of ball bearing or similar so that the plan of pendulum stays constant while the earth rotates? if the pendulum is connected to a ceiling of a building i expect pendulums plane to move along with the rarths rotation since the whole structure/building is moving as well. how did they make pendulum swing independently.
Love the Foucault pendulum and love the way this professor (most physicists) explain it with body movement. Going as far as showing their backside 01:17 and tickling the North Pole 04:50
Don't know why we do it, but probably is related to our enthousiasm of physics.
You may also notice the effect when watching timelaps movies of the interiour of large cathedrals with chandeliers hanging from long suspensions. Although the chandeliers (usually) don't swing you'll see them rotate around their axis until the counter torc of the suspension compensates for the Coriolis force and they jump back to their original orientation.
Love physics, and love this channel. Always entertaining and educational!
I’m going to build one of these in an old building. It will have a vertical shaft where the line attaches. Once per cycle it will oscillate up and down a small distance, giving it the energy to run continuously, without introducing any lateral error. Also a ball bearing where the line attaches.
Did you do it?
If the pendulum is attached to a foundation that's attached to the Earth. How is this experiment accurate considering the foundation is attached to the spinning Earth?
That's the point. If it is not attached than it wouldn't prove anything, would it?
isn't the support with which pendulum is connected rotating along with the earth? it's really astonishing to observe rotation of earth being in the same frame of reference with the earth itself. thanks to foucault
what kind of boggles my mind is that if the pendulum is not suspended in the air (say with a stationary balloon or something) wouldn't the structure its suspended on move with the earth as well cancelling out the effect. It obviously dosent, but.... why not
@Jeeve79 The pendulum is not affected by the rotation of the Earth. As shown in the video, the plane of the oscillation of the pendulum is constant and so the pendulum is moving in an inertial reference frame.
It's also an interesting novel by Umberto Eco.
That magnetic globe is the coolest lamp in the universe
I think I read Foucault had a magnet under the floor that kept his pendulum going.
I want that globe
Shahe Ansar have you found out the model or where to buy it? has some one? I want it too heh
@@CharlyGK7 did anyone find that globe?
Anyone?
Super1Champ The helicopter is still being affected by gravity. So it'll still move with the earth. Just because something is not physically touching the ground doesn't mean it's not affected by the earth's gravity.
Every physicist has their experiment that they get excited about when they hear about it. THIS IS MINE!
How simple an experiment can one person do to explain so much. Greatest showcase of science ever.
4:48 The direction the earth is rotating ... Yes, you can remember. The time zone of New York is about 6h behind London. Keeping that in mind, rotate into the direction where London goes first and New York is behind. Short .. to the east, where the sun comes up in the morning.
The fact that the pendulum's plane doesn't rotate on the equator and the fact that hurricanes don't form on the equator also seems to support this.
Thank you for making this understandable. I always have difficulty understanding what other people are saying, even if the concept is simple, but I was able to follow you the entire time. You have an excellent way with words!
"Excuse me Brady I am showing my backside"
XDDDDDDDDDDDDDDDDDDDDDDDDDDDDD
this is the kind of professor who made college one of the best experiences in my life
@eltotoX Because the stars experience such a small acceleration as they orbit the galaxy, using them as a reference is a very good approximation to an inertial reference frame (non-accelerating, non-rotating). The stars aren't special, they just make a useful reference. Hope that helps.
We have a big one at the university of Salamanca in Spain
I would have very much liked this man as my professor.
6:13 - I like the way he's standing
This is my favorite Professor by far. Always has a witty comment in explanations. Where is he? Hope hes well, would love to hear more from him.
In his own word, "cheeky". A very subtle suggestion that by introducing electromagnetism the museums may be, shall we say, enhancing the spectacle.
but does the roation or earth first rotate the string and then this string rotation is moved to the pendulum at the bottom and that is the whole causal link that changes the orientation of the pendulum ? nobody doesn't explain that if you have something on the string hanging then when you rotate the string it will rotate back to it's "zero" position.
Maybe the apparent motion of the swinging pendulum does not change, it stays the same, but the earth is moving under it, giving the impression that the pendulum is exhibiting precessinon.
Jack Gamboa That's what he's talking about
Maybe? Uh dude were you paying attention to the video or what? Haha
@okuma0kuma I don't think so, the effect of the Earth's rotation is very slight (360 degrees in 24 hours). The force of gravity of say the moon is much stronger I'd say - you get tides from that. I'm no expert, but I think that's what the scientists say on the subject. Oh and the centrifugal force produced by the Earth's rotation will also have a greater effect (conversely on the equator and 0 on the poles):
Location Latitude m/s2(gravity acceler.)
Equator 0° 9.7803
North Pole 90° N 9.8322
As much as I love the quantum mechanics/quantum field theory videos, I still find the classical mechanics videos just as interesting.
Yeeees! Viva, Sir Issac Newton!
The idea that there is a treaty prohibition against trivial and controlled use of flame in a scientific experiment on Antarctica is ridiculous. Any treaty provision against burning on Antarctica would apply to the chronic burning of waste, not prevention of the trivial and controlled use of flame in a scientific experiment. Individual stations on Antarctica would also have strict fire prevention rules, but these would not be codified by treaty; and again, these would not prevent the trivial and controlled use of flame in a scientific experiment.
So you're saying that this guy went all the way to Antarctica, spent all day trying to setup the pendulum then gave up in failure because he misinterpreted international treaty? From what I understand lighting a fire in Antarctica is extremely dangerous due to the high wind speeds, low humidity and vast distance from rescue and medical facilities. Also, there ARE treaties dictating fire use, bases have to be constructed in certain ways and certain distances from one another to prevent them setting each other on fire. In addition there are several facilities and instruments at the geographic south pole, several countries would be quite upset if you burned them all down doing an experiment.
dlwatib Antarctica is one interesting place, just as much for its international relations uniqueness as well as its physical details. :)
TheRhinehart86 LOL yeah, real dangerous to start a fire outside in a barren ice swept wasteland, devoid of any vegetation.
Yup. Water ice is notorious for its high flammability.
Never mind the gallons of petrol they burned just driving there.
Very true, however I said "you can't LIGHT a flame" not IGNITE. I believe that a hypergolic propellant engine would produce to much vibration interference on the pendulum and would also allow more gas into the vacuum making all our efforts moot.
I think what would work better would be a steel string with a small fuse wire connecting it to the pendulum. we then run an electric current, the fuse breaks and the pendulum swings.
so with a pendulum you can measure where north and south, east and west are, cool and also at which latitude you are
Now I believe when Leonard said "I can feel the earth moving!!"
But the support for the pendulum is also rotating....so its the relative rotation that the pendulul swing captures ? or please clarify even at the North and South Pole the Pendulum is attached to the earth and is not floating in space
And if you just think a little about it, you'd see you already answered your own question:
At equator it does not rotate, and at the poles it rotates in 24 hours:
Therefore if you see a rotation of 40 hours, you can work out your latitude.
If I had 3 measurements, I could work out the equation.
I've just searched through the full text of the antarctic treaty and I can't find any reference to the prohibition of open flames.
I have read Allan Baker's website about the experience/experiment and he does indeed state that it is against the treaty.
Anyone have anymore information about this? Seems strange to forbid the use of fire in this manner when the second article of the treaty supports 'freedom of scientific investigation'.
That is all.
My physics teacher linked our class here, it's a funny feeling to know your teachers like he same youtubers as you.
For the direction of the tangential velocity you can use a right-hand-grip-rule... if you imagine your thumb is in the same direction as the vector of the connection of the geografical southpole to the geografical northpole your fingers show in the same direction as the tangential velocity of the earth...
@oisiaa This is Roger Bowley, the professor who does not know which way the world spins. So I screwed up --- it's hard to get everything right when improvising for the camera.
Keywords: "THE TRICK IS..."
can you make it in a vaccum chamber? Remove the air resistance, will it make go for 24 hours?
You probably would also have to mitigate the fact that the wire presents a small torsional resistance. If the planet twists the wire, the wire will twist the ball and everything will be kept together. You could put a magnetic joint on top, though.
@@RSP13 Also hysteretic losses in the wire. Should be possible though, but would need a large vacuum chamber and it's one of those pointless experiments that only flat earthers demand, and they still wouldn't be satisfied with the outcome.
Take something with some length and a bit of weight on the end, maybe like a teabag, or tea infuser, or maybe a pair of headphones with some extra weight at the end or something, and hold your hand out with the end of the string being held by it. Lift the weighted end so it is taught and at an angle where it will swing for a while. Let it go. Walk in a circle, with the focal point of the pendulum as close to the middle as possible.
It swings back and forth in the same plane the whole time.
No, When you turn off an a electromagnet the ball will still remain magnetized for a short time and unevenly release from the magnet. sort of like a "stickiness". this would interfere with the initial swing of the ball.
@dmh497 you do realise that this effect has nothing to do with the earth's movement through space? it concerns the earth's rotation, with a movement that the experiment is tethered to by being on the ground. it would be most noticable on the planatary axis, where centrifical force is at its strongest, although it would be noted on the equator if you started the pendulem from north to south.
In the video there was no mention of the pivot being free to rotate. I'm not sure if it makes a difference in a real situation but wouldn't the pivot rotate with the Earth if it was fixed, in turn making the string rotate. Wouldn't that cause the plane of oscillation to rotate too?
Yes. I would think. Wouldn’t The experiment might be more accurate is they place some sort of bearing at the opposite end of the string. This way the string is not bound to rotate with the earth.
I still remember when I first saw this thing vividly in London Scientific museum. I was shocked. We now could think of many crazy ways of demonstrating the Earth's rotation, but who can imagine someone did this long before space age, in such an elegant way? If I saw this when I was much younger and somehow understood it, I would have become a scientist.
Easy. Set up the pendulum in a vacuum and measure its height above the floor when you let it go. Assuming the string weighs nothing, that tells you the amount of energy in the system (gravitational potential energy). Now let it swing, say, 1000 times and measure the maximum height again. The difference in height tells you the amount of energy lost. A more sophisticated analysis would take into account the weight of the string and maybe even its curvature.
If you would put the pendulum in a void it would increase the period in which observation could be done.
This sounds strange. Respectfully, just thinking aloud. It decays, suggests a motor, discussing experiments in locations that are forbidden to go. But there’s something interesting here I wanna explore! Thank you for the video
@carlsontechnology I would say it depends on the toilet not on which hemisphere it's located. A toilet wouldn't swirl at all if it wasn't designed to.
@ereg1300 for 2 reasons:
(1) you can't create a perfect vacuum
(2) there is still friction in the string of the pendulum, that would - even in a perfect vacuum - eventually couse the pendulum to stop
so a motor is the best solution to this problem ;)
We should add that at South Pole, the idea the pendulum is moving in the opposite direction when compared to the northern hemisphere, is only a matter of orientation. The earth rotates the same way at both poles - face North and the pendulum swings like it does up north.
The pendulum precesses clockwise in northern hemisphere and counter clockwise in southern hemisphere.
Also it precesses as a function of its latitude.
24 hours for 360 degreees of precession at both poles, and zero at the equator.
When you are in the South Pole, every direction you face is North.
@@sissyfus6181 no it doesn’t, that is a fairy tail just like Coriolis effect.
@@tannerotis So when you did a Foucault's pendulum what were your results?
the one at work (radboud university of nijmegen) is driven by a clever magnet setup and during the day you can see the effect which is very cool indeed
Very cool. There is one of these at the Maryland Science Center. I remember it as a child...now I want to go back and see it again, understanding what it actually is.
@Kargoneth Try to imagine it with Vector Forces, If at the poles the Force acts directly perpendicular on the pendulum making it rotate, and at the equator it acts parallel to the pendulum motion, in between both of them, the force should be on an angle which still causes it to rotate around.
looking down at earth from the north pole the earth is rotating counter-clockwise and looking down at earth from the south pole the earth is rotating clockwise
The earth does not spin.
@@desmega7693 LOL
desMEGA YOUR ARE A BRAINLESS MORON
Check out the globe behind him though.
@@desmega7693 Sorry, but Earth is not like your neurons.
I can visualise why it works at the Poles and not at the Equator but for all the middle latitudes all I can do is a mathematical interpolation. I've never really managed a proper mental image of what is happening.
In a similar but different kind of way, this reminds me of the Coriolis effect.
if they made the pendulum outof a denser material (ie: depleted uranium), it would have less air-drag and would swing for longer.
Is it possible to design a more aerodynamic pendulum? perhaps a disc instead of a sphere.
@rjhrjh3 Toilets are designed with the intention of water too rotate, not just enter straight down into the center of the bowl. The nozzles are angled.
Treaty states no fire in Antarctica? I couldn’t find anything on this; anybody have any info?
It really does sound like one of the more clever Troll Physics ideas.
This was infinitely better than Sci Show's explanation.
Here is my example:
If you rotate a mug of tea fairly slowly, the top of the tea in the mug stays still while the mug rotates.
I've just seen this pendulum being demonstrated by James Burke (connections 3). I totally remember learning about it at school but I'd forgotten that the point of it is that that the pendulum is independent to the rotation of the Earth. Amazing! (when I forget which way the Earth rotates I simply remember that the sun rises in the east... so the Earth rotates towards the east... the other way to this video:D)
I really could listen to Professor Bowley speak all day long.
if you can no longer question what you have learned, how would you describe this being?
Philadelphia's Franklin Institute Science Museum put their Foucault Pendulum in the basemen of a large staircase so visitors pass it several times during a visit. There were plaques set up at each floor to explain it. When I worked there 35 years ago I would start the day setting up the brass pins around the base and start the pendulum swinging. They've since remodelled it. The pins are in a much smaller circle and there's some sort of moving globe in the centre. It spoils the simplicity of it.
If the pendulum was suspended from a track and the track was parallel to the equator, and the pendulum was swung perpendicular to the equator, would the pivot point of the pendulum move along the track? Meaning the earth would move independant of the mass of the pendulum? Since the pendulums mass is moving faster in an oblique direction. Of course you know which direction the earth rotates, the sun rises in the east and sets in the west. Its this perpendicular movement which changes the angle
If the suspension point of the pendulum is fixed, doesn't it acquire a torque as the Earth rotates, or is it the torque that causes the pendulum to change the direction of its swing? What if it was suspended on a frictionless, torqueless mount?
You answered yourself in the last part of your comment.
At least as "frictionless" as can be.
To unrealeck's comment (Assuming the comment he was replying to was about a helicopter moving across the surface of the earth as it rotates:) Actually the helicopter isn't moving because of the gravity. Gravity is only its attraction to the earth, not the holding of its position relative. The helicopter would indeed move with the earth, however that's because it was already moving with it. The earth was spinning and, as such, since the helicopter was on the surface of the earth, so was the helicopter. Since nothing slows it down when it leaves the surface of the earth, the helicopter will keep moving with it.
For example, if you're on a train and you toss a ball upwards, ignoring possible wind, the ball will keep moving with you. It holds that relative velocity. Same for a helicopter getting off the surface of the earth.
"It goes around the opposite way in the Southern Hemisphere compaired to the Normal Hemisphere." I had to play that back several times to make sure that's what he said.
He's a hemisphere-supremist 🤣😆💯
They have a big one at the San Diego Natural History Museum.
wow, awesome video. got one at uni and very really understood what it was about... cheers
@dmh497 This experiment is concerned with rotation, i.e. change of direction- not simply speed, as you have referenced. As it takes 200 million years to orbit the milky way. You will not see the effect of galactic rotation on the pendulum.
4:35 I want thi- no I NEED THIS!
Very well explained thank you i subscribed
This demo should have been built on a turntable rotating once in roughly the time taken to swing down. It would require a lot less explanation that way.
@dmh497 Well, light itself takes a few minutes to get here from the Sun at 180,000 miles per second, so the Earth has to go kinda fast to travel all the way around the Sun in one year. We don't notice it because we're going at the same speed, and so we were even before we were born. Like when you're in a plane and once it takes off you don't even feel like you're moving.
I like simple experiments that reveal something we can't sense. Nice job :)
lol i love this guy
the damn thing
@MrOldprof My deepest apologies sir. I seriously respect your knowledge and absolutely love watching you on Sixty Symbols. It was my error to point out such a simple mistake that anyone could make.
Has anyone thought to set up a foucault pendulum in a vacuum?
That is raw how that earth model was rotating at 4:38. IN THIN AIR!!!
The big church in our city also has this demonstration. Pretty cool actually.
I found no reference in the treaty of Antarctic about the usage of flames, and I must admit it sounds preposterous given the fact that the same treaty recognizes the use of the Antarctic as a place for scientific experimentation (which involves the use of fire in numerous ways). Can the uploader please provide links with evidence to suggest this? Because if it is an anecdote, I believe it should be mentioned. Many people take things said in this channel for granted.
But sir the ceiling that the pendulum is connected to
Is a part of the earth itself.
When the ceiling rotates the pendulum will rotate with it too.
How you say it's not rotating.
"I can't remember which way it [the Earth] rotates"
Pretty hilarious said by a man like him :P
Hey, my college has a huge version of one of these installed our library. Come to think of it, I have no idea if it was put in by the physics department or the psychology department, because only a very small percentage of students (now including myself) know what it is, which makes for a great opportunity to watch confused freshmen question their sanity when they emerge after a long study session to find that the pendulum is moving in a direction completely different from when they came in.
@8DX As well as obvious gravity but wind / pressure is a factor on the pool of water surface weather it is high or low i think it is part of coriolis effect isnt it !
quaternion
Excellent explanation. Amazing experiment.
This is some amazing quality content
I'm pretty sure the earth rotates the other way
it does..........and he's a scientist ? ppppffffhhhhhttttt WETF
Chris Jones
You are correct
He pointed out he might be wrong
The earth does not rotate, it is immovable.
Pretty sure the earth doesn't even rotate. LOL!
Then influenced by centrifugal forces? If so, how does this differ from gravity?
@tvalerianopereira Try it yourself with your own pendulum. Get a heavy weight and set it in motion, then manually twist the apparatus round 360 degrees yourself and watch what happens. I don't think the plane that the pendulum moves in should or will change, and it's the same when the earth rotates.
So is it really only air friction that stops the pendulum in time? Are there other effects at a smaller scale that dumps energy out of the system (friction at the point where string is attached to the system for example?)- my point is, what if you did that experiment in a relatively vacuumed chamber? Modern vacuum chambers go down to ~1e-8 bar perhaps?
Most of the energy actually doesn't is the cause of air friction but instead the loss is due to friction at the contact surface where the pendulum is fastened to the ceiling (or wherever it hangs) as you mentioned. A bad anchor takes quite a lot of the energy of the pendulum.
Actually, the earth isn't moving slowly under your feet. At the latitude of the UK, the rotational speed is about 600mph.
Yes. You'd have to set up a pendulum at a pole. And let say you sit on the pendulum. If you start with the sun un front of you, one season later the sun would be on you left, then behind you, and so on. It would take 1 year for you to see the sun goes around you. Of course, since the Earth's axis is tilted, you'd have 6 months of night, while the sun shine on the opposite pole. And you'd see the Moon revolve around you in about 27 days too.
when the earth rotates, does air rotate with it? I have seen little toys and such (kind of like the globe in the video) that can levitate, if someone was to up a mark on the levitating toy, after 24 hours would the mark be pointing in a different direction?
yes and there would be less friction, (none from air) so it would work better.
You've never heard of an electric stove, have you? There's also things like chemical reactions, or insulation to keep things like biological heat from escaping, or maybe even using special types of lenses designed to take sunlight and focus that into a beam like a magnifying glass... Plenty of ways to generate heat without using open flame.