Foucault's Pendulum - Sixty Symbols

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.sixtysymbols.com/
With Roger Bowley

[@TheZooman22]

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.

[@charismatic1516]

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?

[@ginnyjollykidd]

He got it right, though.

[@1977ajax]

@@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.

[@theultimatereductionist7592]

4:49 "And I can't remember which way it [the earth] rotates." The humility of a true scientist!

[@MajWinters100]

@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.

[@MajWinters100]

@Roman M. deaf ears, and blind eyes, I see

[@MajWinters100]

@Roman M. true, you're the one calling people idiots first. Thanks for pointing it out.

[@arcticredranger105]

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?

[@alokj84]

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.

[@hikoseijuro7977]

"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.

[@UguysRnuts]

Heretics

[@southpaw8168]

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

[@twocyclediesel1280]

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.

[@simonneumayr6002]

Did you do it?

[@xbox360player88]

@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.

[@agerven]

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!

[@WolfenLove]

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!

[@markw6457]

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

[@metfan89]

wow, awesome video. got one at uni and very really understood what it was about... cheers

[@mat060]

Excellent explanation. Amazing experiment.

[@AzraelCC]

It's also an interesting novel by Umberto Eco.

[@BGenerous]

@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.

[@arandomchannel56]

Very well explained thank you i subscribed

[@300Z31]

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.

[@tunnis7us]

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.

[@km-sc4kz]

When the pendulum is at the equator, would it also be possible for the pendulum to slowly stop oscillating and then be sort of fixed hanging towards the west- because the earth is rotating towards the east Or would it just keep oscillating in the same plane (neglecting any sort of resistance).

[@525047]

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.

[@jamilinsaaf7374]

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

[@pnBonanza]

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...

[@puretroubleman]

@mvszao as far as I can tell it uses a 1 magnet in the stand, the top of the globe has some type of metal probably steel or iron and a electric force which i assume flips the fields so quickly that it repels and attracts so that it can not move.

[@lisawilliams7836]

What a lovely explanation 😊

[@911gpd]

That magnetic globe is the coolest lamp in the universe

[@P00P0STER0US]

I like simple experiments that reveal something we can't sense. Nice job :)

[@andirunner1]

Really enjoyed this clip. I am not at all mathematical but this made perfect sense to me. My son would really connect with this. Any tips on setting up a suitable experiment for a nine year old would be appreciated. Well done!

[@raykent3211]

Thinking back to prof B on a swing moving his weight up and down (nearer and further from the fulcrum), couldn' t you put a battery powered device on the big weight which moves a smaller weight in this way? Could keep going until the battery is flat. Not as elegant as the original, though.

[@IronAnimation]

My physics teacher linked our class here, it's a funny feeling to know your teachers like he same youtubers as you.

[@okuma0kuma]

@physicsbugga wind is a factor to include on this myth something of larger scale like a hurricane vortex do they form in different direction depending side of equator they begin ?

[@TristanMorrow]

So, how long does a pendulum take to loose all of it's energy? Is there an easy (or hard) way to calculate that? I imagine that a couple coefficients of fricative force apply, but please enlighten me.

[@Randomstuff77654]

This is some amazing quality content

[@somedude4122]

I want that globe

[@CharlyGK7]

Shahe Ansar have you found out the model or where to buy it? has some one? I want it too heh

[@YiannisANO1911]

@@CharlyGK7 did anyone find that globe?

[@GEAsolar]

Anyone?

[@DaSauceful]

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.

[@okuma0kuma]

@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

[@obsoleteButter]

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?

[@k39564]

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.

[@jdunk2145]

Would it be possible to cut down the friction of the air in a vacuum to keep the pendulum moving for a longer period of time?

[@turevus]

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?

[@utl94]

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.

[@Silk_WD]

@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.

[@johneonas6628]

Thank you for the video.

[@Legolaaa]

@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.

[@Jose-pq4ow]

We have a big one at the university of Salamanca in Spain

[@N3bu14Gr4y]

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.

[@ytashu33]

Awesome video. I was interested in the last point though (the relationship of the plane of oscillation with respect to Sun and distant stars etc). I watched that segment (towards the end) again and still am not sure what exactly is the conclusion. Is the plane actually constant with respect to the distant stars, or not?

[@SoundbytesMusic]

I would assume that earth rotation around the sun does not effect the pendulums plane of oscillation. Our daily rotation is a spin effect while the annual rotation is caused by gravity.

[@nofacee94]

@mrblisterfist counterclockwise is used for 2D but what's used for 3D? if the earth rotates counterclockwise from the north pole, it is the opposite direction from the south pole.

[@2041311]

6:13 - I like the way he's standing

[@yusukeshinyama]

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.

[@1xtra299]

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.

[@UguysRnuts]

In his own word, "cheeky". A very subtle suggestion that by introducing electromagnetism the museums may be, shall we say, enhancing the spectacle.

[@craig3.0]

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.

[@alcapwned86]

Do they have an episode that talks about the "natural" reference frame in which the CMB is (more or less) isotropic? Also proper distance vs. comoving distance. And the size of the universe (i.e. I know the observable universe is finite, but is the entire universe infinite? I mean, there can't be some wall somewhere, so if you were to travel in one direction forever you would never hit "the edge" of the universe, but is that due to expansion, or because the universe is truly infinite?)

[@CHistrue]

Do a video on the various periods of rotation of the Foucalt pendulum and relate it to conservation of angular momentum. It would be a great video!

[@kiranvijayan1289]

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?

[@comface]

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.

[@athiest100]

Loved it ...

[@DaSauceful]

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.

[@canvent]

Brilliant!

[@wowsa0]

@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.

[@roidroid]

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.

[@Renato404]

can you make it in a vaccum chamber? Remove the air resistance, will it make go for 24 hours?

[@RSP13]

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.

[@ferrumignis]

@@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.

[@tiredfingers99]

@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.

[@kght222]

@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.

[@DanielJPowell1]

Good explanation. :)

[@8DX]

@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

[@MrOldprof]

@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.

[@jugbrewer]

As much as I love the quantum mechanics/quantum field theory videos, I still find the classical mechanics videos just as interesting.

[@charismatic1516]

Yeeees! Viva, Sir Issac Newton!

[@McPrfctday]

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)

[@sachiperez]

Treaty states no fire in Antarctica? I couldn’t find anything on this; anybody have any info?

[@wokeupinapanic]

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.

[@DarrenHerbertII]

Hello Professor! I love your video's so much, thank you endlessly for sharing your knowledge! I'm hoping to come study at your university soon after doing an access course at college this year. I did a years foundation course for engineering at London South Bank University but didn't finish for health reasons.My question is about the Precession of Earth as discovered by Hipparchus in 130BC and the alignment of Polaris as a marker for our rotational axis.. Apparently this cycle is renewed every 26,000 years. Does this tie into our Julian calendar or even the fact that we measure time from 0AD? Christianity seems to cloud my sensible reasoning, although I do not deny that such events did indeed happen.. To some extent!Thank you very much,Darren Herbert, aspiring student! :)

[@srfriggen]

this professor is so awesome.

[@rkalle66]

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.

[@tyroneslothdrop9155]

This was infinitely better than Sci Show's explanation.

[@EmdrGreg]

So if you set a good pendulum system into motion with great care and no jostling, the pendulum will not make those patterns you see in people's sand pendulums? Those oscillating patterns happen only because the pendulum is started off with some 'non-planar' or irregular motion to start with? Is that basically correct? I'm very curious about this; it's very interesting.

[@leonpolya9184]

Foucault's pendulum that resides at the Science Museum, London had quite a profound effect on me when I was reading pure & applied mathematics at Greenwich. To see a demonstration of FCP you must have a heavy weight suspended from a very long taut wire released at an angle of about 30 deg. The linear inertia of the swinging pendulum (fixed relative to the stars) must be great enough to overcome the rotational inertia force acting on the pendulum of a rotating earth which though small is apparent and will take a small weighted pendulum on a short wire around with it.

[@EmdrGreg]

I see! That's mind-blowing. Thank you, leon.

[@philinator94]

@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 ;)

[@nolongerlong]

@zanderzander05 Amazon sell them - just search for globes and they have a few magnetically suspended ones.

[@jlsmith4054]

Then influenced by centrifugal forces? If so, how does this differ from gravity?

[@yetanotherjohn]

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.

[@kknd-krossfire1114]

Jack Gamboa That's what he's talking about

[@ct8618]

Maybe? Uh dude were you paying attention to the video or what? Haha

[@Mcgrandma]

Would this explanation be the same example for the coriolis effect at the equator? They give a demonstration there of water in their pan circling in one direction, then take a few steps to see it circle in the other direction trying to prove that the equatorial line separates the two spins.

[@pantaristeski3534]

that is for the tourists only, can't feel the differences for couple of meters.

[@Mcgrandma]

It's wild that the earth can rotate water into a circle, yet large planes can fly around a rotating earth and not land sooner because the earth moved under them. Our hair should be flying with the rotation especially at the equator going about 1,000 miles an hour.

[@Mcgrandma]

Well, we've always been taught the earth rotates with us. Don't believe everything you've been told. Think for yourself. True, if you're in a car, plane or train, you can't tell how fast you are moving. But the earth is not inside an object. It has air above it. Let me guess, the atmosphere holds it in like velcro. Maybe "space ships" pop through it when they go beyond it like the ISS that has no gravity. We're hurling 1,000 mph + 67,000 mph + 500,000 mph + 670,000,000 mph and don't even feel a slight breeze on our faces. No motion whatsoever? I have trouble believing that.

[@pantaristeski3534]

Marcia lele don't listen they told you think with your own head. First, earth is not inside something but earth doesn't feel anything, you feel and you are inside the earths atmosphere. And yes air is stickied by gravity as Velcro . Now wen you are in plain moving with 900 km/h what is amount of speed you feel? None, zero ! Even pilots don't feel the speed without an instrument. Do you know the concept of multiplication whit zero ? Suppose you do, then if earth is moving thousands time faster then plane you feel speed zero * thousand * million * billion = ZERO !!! That is all, you can't feel speed humans don't have sensors for speed, we only have accelerometer :) an can feel acceleration.

[@TheWorldgonecrazy]

Try landing a plane with a 1000mph + your air speed ...you get the wrong direction you're going to crash. But lucky the Earth is stationary as seen as felt as is!

[@unrealeck]

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.

[@duman-sv3ms]

if you can no longer question what you have learned, how would you describe this being?

[@bmo5082]

I would have very much liked this man as my professor.

[@soulvibe2007]

@Kargoneth nice idea :)

[@dlwatib]

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.

[@TheRhinehart86]

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.

[@sinephase]

dlwatib Antarctica is one interesting place, just as much for its international relations uniqueness as well as its physical details. :)

[@rcook2608]

TheRhinehart86 LOL yeah, real dangerous to start a fire outside in a barren ice swept wasteland, devoid of any vegetation.

[@pansepot1490]

Yup. Water ice is notorious for its high flammability.

[@massimookissed1023]

Never mind the gallons of petrol they burned just driving there.

[@perrymalcolm3802]

I think I read Foucault had a magnet under the floor that kept his pendulum going.

[@aliensoup2420]

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?

[@sissyfus6181]

You answered yourself in the last part of your comment. At least as "frictionless" as can be.

[@rangedfighter]

so with a pendulum you can measure where north and south, east and west are, cool and also at which latitude you are

[@chrisofnottingham]

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.

[@AlSavant]

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.

[@Christophe_L]

Could you please explain inertial reference frames please? I mean I understand what an inertial frame of reference is but... why the distant stars? Why is the pendulum stationary with respect to them and not to something else? I have been thinking about this for ages and can't come to a reasonable conclusion. It's as though these stars were special, but I suppose even if you went really close to one of them you would still think about other stars as being distant. It would make a good video!

[@EclecticSceptic]

So interesting!

[@hansajaherath7159]

"Excuse me Brady I am showing my backside" XDDDDDDDDDDDDDDDDDDDDDDDDDDDDD

[@Kevin-sy8uf]

this is the kind of professor who made college one of the best experiences in my life

[@MeriaDuck]

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

[@Tossphate]

@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.

[@Nilguiri]

@wesmatron Do you think the Allais effect is a myth? It certainly seems ridiculous, but has it been definitively ruled out?

[@yondaime500]

@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.

[@silentelysium]

Whoooaaa, that's a very cool globe! Where can I get one?

[@Ciumpalacu]

Thank you sir

[@oisiaa]

@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.

[@RMoribayashi]

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.

[@ravi95730]

What if you make the Pendulum swing in the North South plane at the equator?