The Golf Ball Paradox
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- čas přidán 24. 05. 2024
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Sometimes a golf ball with pop back out of the hole. The physics behind it is quite surprising. Watch it happening in slow motion.
Here's a great analysis from Daniel Walsh: • Response to Golf Ball ...
Check out the Turntable Paradox video here: • The Turntable Paradox
Check out the Motion Amplification video here: • Reveal Invisible Motio...
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Here's a great initiative explanation from Daniel Walsh: czcams.com/video/4er2buINHF0/video.html
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The golf ball's dimples caused this effect
Could you not put a mirror at a 45° angle above the cylinder and pull the frame of the highspeed camera back to see both angles at the same time?
Would an amplification video of a bridge with heavy traffic rolling over it or a skyscraper building swaying in the wind be of interest?
Motion amplification under electron microscope. Could you see atoms vibrating?
would be fun to see what tree's or buildings look like in different levels of wind?
I have been conducting a version of this experiment for years, I can confirm that it’s impossible to get a golf ball to do anything you want it to do.
Truth!
Unless you are Tiger Woods? :D
slap a mask and digital covid certificate on it and it will do everything you want it to :D
Going for the high score instead of the low score, huh?
@@bogdy72000wtf?
Motion amplification on Musical instruments might be very interesting, to see the resonacne of the notes in the body of the instrument. to see what parts of a violin, piano or guitar move, also maybe for a flute or xylophone or something like a trumpet..
All parts of the instrument, not just the obvious parts. Maybe even the floor the piano sits on. Does a solid concrete floor change the sound a piano makes over a wooden floor?
Oh yes, I'd love to see a harp soundboard.
It was my first thought as soon as he said it👍
As a guitar player I say: guitar!!! Acoustic as well as solid body electric.
@@maxximumb Church organs! The cathedrals themselves help to create the classic organ sound. It would be so cool to see how a cathedral responds to organ playing!
Collab with @AskOlafTheViolinmaker, showing effects of soundpost placement would be fenomenal
There was a thing I saw where a camera focused on a bag of chips through a window could measure the vibrations that speech made on the bag in order to reconstruct voices inside the room the bag was in. I’d love to see that sort of thing amplified.
That's the idea behind laser microphones
@@oelboy it's why you aim a loud speaker at your window(s) to defeat laser microphones
@@greggv8or curtains
@@greggv8 I do that strictly for the tunes.
That has been in use for surveillance for about 50 years.
I work on violins and bows and I would love to see motion amplification of a violin back and compare it with different shaped violins, to see if you can tell them apart visually as well as aurally. Maybe you could also test bows by sending a pulse down one and watching it resonate. You could compare different wood types and structures as well as densities and thicknesses.
I play violin and would also love to see something like this or related
I had a similar thought- but with other instruments as well- how much does a guitar body vibrate, or a grand piano?
Was thinking about a very similar idea. Would be very interested to see how and where different brass instruments vibrate, and the more fine vibrations of a brass musicians embouchure!
If you use spheres coloured in yin-yang style (each hemisphere and its pole with contrasting colours), it may be possible to see if the axis of rotation stays consistent in the entire action on the slo-mo camera.
I was thinking the same thing
Or just draw a couple lines around the ball
Draw several points all around the ball, like face motion capture for movies is made
Yeah. Why didn't he just draw an equator around the ball.
@@TheEgg185 He's milking it for a second video.
YES I HAVE AN IDEA! The motion amplification camera video was one of the most interesting so far, and it really jogged my brain. I would love to see which parts of an acoustic guitar vibrate the most when played.
The entire body is a soundbox, but certain parts vibrate more than others, leading to differing ideas of how guitars should be braced internally to strike the balance between stability and resonance. In my experience with feeling the body while playing, the area around the bridge (understandably) feels like it resonates the most, whereas the areas surrounding the sound hole seem much less resonant.
The whole idea may require a somewhat elaborate setup to hold the guitar very stable, but I think it could be a fascinating video.
Great idea. Actually the parts that move most will change with different notes (fundamental frequencies) that are played. I would love to see this in action.
Or an electric guitar under amplification. We've already proven that tone is in the EQ and amplification stages but it would be cool to see.
I think the strings might vibrate the most, but I could be wrong.
@@chasm9557 Yes, but the strings make a very small part of the sound. The top of an acoustic guitar is designed to move air because of the movement of the strings.
I would love to see the inside of a grand piano filmed. Especially because due to resonance, when you hit one note, many other strings start vibrating without being touched depending on their resonant frequency. Very cool
Regarding your motion amplification camera: If you're still looking for ideas, I'd recommend small aircraft. I work at a flight school and it's always amazed me how the vibrations of the engine can ripple through the airframe and have an effect on parts which (to the human eye, at least) seem incredibly stable. It could useful to see the amplified difference between a "perfectly balanced" prop and one which is very nearly balanced.
Seconded
Very impressive analysis . It's great that you take the time and effort to understand something that very few would give a second thought and then make what you discover available to us . Congratulations !
For the motion amplification, I would be interested to see how houses and surrounding area reacts when a train passes by. Like what effect is the train have as it is rolling across the tracks. We just moved into a house with a set of train tracks behind us and when the train passes by it feels like the whole house shakes sometimes.
Yep, my parents house has tracks 20m behind it. When it passes by you can see water shaking in a glass.
It's called Living Next to an Effing Railway Line, what did you expect?
@@andrewemery4272bro the question is why it happens not if it happens.
So most architecture has a natural amount of 'sway' to it that (for the most part) will resist heavy vibrations by lightly rocking with the vibrations. They intentionally build skyscrapers with a certain amount of vertical flexibility to account for wind and earthquakes, and in earthquake prone areas they build most buildings to lightly rock when heavy vibrations are present. Both types of architecture use this natural principle found in almost all types of structures. Certain types of material are naturally more flexible, even if they are seemingly rigid structures. Metal is more flexible than wood, wood is more flexible than concrete and brick, and so on.
Essentially, when the train rolls through, it heavily vibrates the flexible metal tracks. Those vibrations spread through the ground and to the foundations of your home, and your home proceeds to lightly shake. It may seem like heavy shaking, but the structure as a whole is not moving that much, the flexibility of the structure makes it seem worse than it is, but also protects the home from falling to pieces.
Yeah that would be interesting! I used to live in a house with a railway line that went through a tunnel pretty much directly under it
One mirror over the top of the cylinder would give you two synchronized views.
Clever
Was just going to say that 😂
Or just film with two cameras that capture sound and clap to line them up
sound of each camera might be off by a different amount.@@just2607
@@just2607 Just? 🤨
This also works with individual collisions in a square tunnel, instead of rolling with continuous contact:
czcams.com/video/AfPhuwBItB4/video.html
The closest thing I can come up with to an intuitive analogy for what may be going on is from playing with marble mazes as a child. If you throw a ball bearing around a funnel in an elliptical orbit, you get the same pattern. The ball keeps missing the hole in the funnel and running back up the other side. This shape makes intuitive sense. Now all we have to do to make what the ball accomplishes in the cylinder intuitive, is to slowly augment the shape of the funnel until the funnel *is* a cylinder. Even with the cylinder, the ball is attempting, and is, following an elliptical orbit and "missing" the hole at the bottom of the funnel and running back up the other side. The fact that this works with the completely vertical sides of a cylinder rather than the more angular sides of a funnel, and the fact that it's more difficult to intuit and elliptical orbit inside a cylinder, is where the bizarre intuition break happens.
It would cool to draw dots on the squash ball (or the smaller ball) to be able to track more precisely the axis of rotation (kind of like you get on some pool balls to illustrate the effect of spin).
Yeah, I think that the action happens because it's a curved ball 'rolling' on a curved surface. With enough force applied to set the ball in a rolling motion, the curvature of the cylinder and the curvature of the ball makes it spin on a different axis, causing it to 'turn' while it rolls. This might be simple and i'm talking out loud, but that's the part i'm interested in
@@foreverspellmanI think you're on to something. That's why the flat surface attempt fell flat. 🙃 This should have been a main response.
Yes, I was wondering why he didn’t draw lines or dots on the balls to get a better “intuitive” grasp of what was going on as they spin around the cylinder.
@@4g0tten4 ' draw lines' Yep just saw this and the first thought on seeing it, small grooves with a bright color like 3 or 4 latitude lines would show what's going on much better. Especially the once in a while you got the lines basically in line with the roll direction of motion, you would easily see the steering that is going on besides just the rolling of the ball.
It's there a little bit in the video, some tracking with the squash ball logo. But of course it would be much better with full lines.
@@bromero88 I wonder if you had an much larger circumference cylinder, would this change? The larger the circle the more like a "flat" surface it should operate? Specifically the ratio of ball circumference to cylinder.
The motion amplification camera is the coolest thing i've heard of in such a long time.
to me it's super creepy for no discernable reason
I'm curious if it would show something with musical instruments, especially wind instruments like flutes and trumpets.
@@petervanderwaart1138 great idea!
@@petervanderwaart1138 will a camera meant to record vibrations be able to record instruments that work because of vibration? What do you think?
@@Dragoon710they're wondering what it would look like if the vibrations picked up by the camera are great enough, Sherlock
It would probably be easier to visualise what’s happening if you'd drawn three differently-coloured circles oriented peripendicularly to each other (like representing x, y, and z coordinate planes) on the ball. It would ease tracking rotation and direction in slow motion.
same thought, I think lines can also work
0:07: 🤔 The video discusses the phenomenon of a ball being thrown into a cylinder and coming back out again, exploring the concept of centrifugal force and gravity.
2:23: 🎥 The video discusses the ratio of turns between a ball and a cylinder and relates it to the turntable paradox.
4:55: 🔍 The video discusses the ratio between the wall thickness and the square root of a squash ball, as well as the ratio for a mouse ball, and suggests possible explanations for the differences.
7:32: 🎥 The video explains the intuitive explanation of the gyroscopic effect on a ball thrown in a cylinder.
9:56: 📚 The video discusses data brokers and how Incognido helps individuals protect their data.
Recap by Tammy AI
Thanks for saving time! Amazing summary tool with lovely time stamps!~ where u download this Tammy AI?
I'd like to see the motion amplification of an interior of a car, with the engine running. It would be especially interesting if there were some sort of buzzes or rattles in the dashboard. Hopefully the motion amplification could pinpoint where the noises were coming from, as it can be hard to locate with your ears.
Yes! I bet the rearview mirror goes bananas at certain rpms.
My RV gives me a headache on the road.
The body panels on a classic muscle car idling probably do lots of wiggling
I can't explain but I think that would be hilarious. Just seeing, like, the vroom, but visually.
Was going to comment this but thankfully, that work has been done already. Please use this camera on the interior of an ICE vehicle on startup, and maybe also while running. Thanks Steve!
For motion amplification you could show cars at a subwoofer competition. It’d be fun to see how the people inside look with it
oh yeah that'd be funny to watch car trunks wiggle at 40hz
Many car related things: body panel deformation; tyre deformation and rebound; dragsters; race cars and bikes.
Planes; suspensions; buildings flexing.
I had the same idea but with a rotatory subwoofer, wich can go down to 5Hz or even less. But that works best on a house i think.
PD: Also rotatory subwoofers have a lot mor dBs
At infrasonic frequencies they will generally produce much higher SPL that linear motor subwoofers. But at audible subsonic frequencies a traditional subwoofer will be superior for SPL and have much lower distortion. Modern competition winning builds for standard vehicles (not extreme vehicles) push over 160dB and on occasion even over 170dB which is physically unbearable for a human loll. Tap out territory is usually in the low 160s for most people. Extreme style vehicles get into the 180s but those can only a test tone to get those numbers.
A rotary subwoofer allows for extremely high SPL at low frequencies because they ingenuously and blatantly violate ‘excursion law.’ (Not sure what to dub it). But essentially with a normal linear motor driver, for every halving of the frequency, you need four times the excursion to maintain the same SPL (assuming there is no role play by the enclosure, infinite baffle). A rotary subwoofer completely gets around that by introducing a time constant, since the blades can continuously move air in either direction and reproduce DC. If you cut the frequency in half, then the fan just has twice the amount of time to move the air, thus no more excursion law. And at 0Hz, the fan can just move air continuously in one direction, being the equivalent of infinite excursion
That’d be awesome. Although some builds now are so ridiculous you wouldn't even need it 🤣🤣
For the motion amplification camera, I think it'd be interesting to see motion in various sports contexts. How does a bat, hockey stick, or racket vibrate through impact? How does impact affect the ball? How about the human body? How do our muscles vibrate when running, jumping, swinging, etc.? Hopefully the macro motion doesn't cause any issue capturing the micro motion in these cases.
6:58 Wow! I didn't know that this RDI technology was a thing and it's fascinating. I'm so excited to watch your video on this topic that you mentioned. I love learning about something I've never considered before
You could film the top and side view at the same time by filming from the top and putting an angled mirror in frame next to the tube to give you the side view.
Kinda like the opposite of how they use a mirror to align two big cameras when they film 3D movies.
Or vice versa. film from the side with a mirror above for the top view. That way you don't have to get fancy with the camera mounting.
@@b.s.864 that’s probably easier… lol my brain just immediately jumps to the most complicated way to do things…
“I have a flat tire.. let’s push the car over by that huge tree, and then someone bring me 5 pulleys, a snatchblock, some industrial chain and dyneema rope. I’ll need nine strong men and a Girl Scout…”
“Or we can use the jack in the trunk…”
“Oh… right. Yeah… that works too.”
Haha
@@DanteYewToobWhich way is easier would be highly circumstantial. For instance the TV show Good Eats reportedly used the vertical camera option for many of it's cooking shots with a sliding mirror to switch to the host.
I guess the easiest way to figure out what happens should be painting the ball on equator and on poles, shouldn't it?
if the axis of rotation changes, poles and equator would change, plus lining it all up at the beginning would be a huge challenge. but marking the ball in some way should let us see the rotation
You would paint a red line across the equator, a blue line across the 0 and 180 degree longitude and a green line across the 90 and 270 degree longitude.
Just evenly cover the surface of the ball in dots then it shouldn’t really matter.
You could paint it like a soccer ball
@@NicoMelone painting it may not yield the same results since the paint material might not display the same properties as the original surface. A line would be a much better idea. I think pronounced dots would be an even better idea! 6 or 10 dots to mark points 90 degrees apart and let the fun begin!
Give me your ideas for motion amplification videos! Heat causes things to expand. Can your motion amplifier record the change in volume or dimension of an object that heats up. . . .by light hitting it? IR? by rapid changes in heat application? etc?
My first instinct was that the ball is essentially bouncing with extra steps. The centripetal force gives enough friction againt the wall that it is able to elasticly return the downward component of your initial throw. The gyroscope effect keeps the ball from just rolling down the wall by limiting its ability to spin in that direction.
For the Motion Amplification Cam, maybe a collab with Look Mum No Computer with the organ he repurposed at his place. There are some huge pipes that will oscilate when the air passes through them and you can fit dozens of these pipes in frame to see how the size affects the oscillations.
That would be cool
That's a good idea. Gun barrels are another possibility, it's one thing to know theoretically that tiny pressure bulges travel up from breach to muzzle but it would be fascinating to actually see it.
Playing a chord would be fantastic. You could see the pipes go in and out of phase with one another, or explore beats with two similarly tuned pipes.
This would be hugely awesome collab on all levels.
Steve Mould and Look Mum No Computer definitely needs to happen.
Put 3 stripes around the ball, 2 from top to bottom offset by 90 deg and a third around the “equator”. Each stripe has a different color. This will help show full motion range of the ball. You could also keep the strips solid color and instead color each of the 8 sections a different color. Then enlist the help of the slo mo guys to do a collaborative video about it.
Great idea
I love this!
"enlist the help of the slo mo guys" should be on the to-do list of every single CZcamsr, no matter what the video subject is.
Or use color, if the strips modify the rotation too much.
Suggestion for the motion amplification camera: The top of an acoustic steel string guitar. You should see the different modes of the guitar, changing by string and by note. The modes are very complex and would be really interesting to visualize.
If you pay really close attention to the high speed shots, you can visually *see* the axis of rotation changing on the balls by watching their surface texture's spin. You'll notice that the axis seems to "flip" at that midpoint in the osclilation. If you take that initialy intuitive explanation of the ball's axis of rotation remaining the same as it travels around the cylinder, you can very clearly see that happening in every shot (its easier for the hollow ball shots, since its surface texture is less homogenous and easier to discern). But at just about the end of that first go-around you can see the ball very quickly and very suddenly flip its axis of rotation the other way, thuse steering the direction in which it spins.
You can basically "trace" their movement along the cylinder and find that it very very closely mirrors that sort of up and down spinny rotation of a spun coin as it nears the end of its spin. The balls in this case are basically tracing the edge of that coin as it spins, first going in a Top-left/bottom-right diagonal and then a Top-right/bottom-left diagonal
Now you're making me think of Veritasium's video discussing the intermediate axis theorem. I know a sphere doesn't do that, but I'm pondering it.
When Steve unrolled the cylinder I see that as an incomplete model as the diameter of the ball relative to the cylinder affects how the contact patch moves (as does the surface squishiness). Imagine a rounded motorbike tyre steering with the castor angle.
Combining it with the coin rotation paradox and throw in this idea of gyroscopic axis preservation and I think he's come up with a pretty good way to visualise the concepts going on with this one.
Anyone want to model or try the same thing with non-spherical rolling objects?
I think a cool object for motion amplification video would be a string instrument like a violin or a cello (Maybe a double bass depending on the maximum frequency of the camera) would be cool - there's a lot of engineering of the shapes of these instruments to control the harmonics of the sound.
Also, you don't need 2 high speed cameras if you have a good mirror, that way you don't need to sync your camera streams
Edit: Typo
I’d love to see that! The physics of amplifying low frequencies geometrically is also a really interesting topic.
Yes please
I can't picture how to position a mirror to get a horizontal view and a top down view with a single camera, can you explain?
@@swirle13put it at a ~45° angle from the camera (a little shallower for fov reasons) above the cylinder. It makes more sense if you draw arrows from the camera to the cylinder, you'll see that you have the direct path from the camera to the cylinder to see the hoz and then the mirror will bounce the view directly down the middle of the cylinder for the vert
@@swirle13 Sure: assuming that your camera has an aspect ratio somewhat similar to 16:9, point the camera vertically down with the top down shot taking up the right hand of the frame.
If you position a mirror with its bottom edge touching the base of the cylinder you should have enough frame to get a somewhat reasonable shot of the side.
Would love to see motion amplification of a 3D printer, to be able to see the different vibrations that occur as it moves around. A comparison between a cheap and expensive printer would be cool too!
Cool idea! I'd love to see a comparison of the different stepper drivers (A4988, DRV8825, TMC2130, TMC2208, etc.) as well, but that seems more like a CNC Kitchen video than a Steve Mould one
@@hadinossanosam4459oh that's a great review strategy
The intuitive explanation seems easy to come by and you nailed it I think. Conservation of angular momentum where imparted momentum eventually matches velocity at the contact point then through friction becomes an acceleration force through conservation of angular momentum while simultaneously and continuously sustaining additional conversion of velocity to angular momentum to match surface contact velocities at the tangential contact point.
Musical instruments for the vibrato camera would be extremely cool, especially woodwind instruments where it's kindof unclear where the sound actually happens; for strings its the strings, for brass its the bells, for woodwinds it's generally the tone holes but it would be nice to see that visualized.
Motion Camera Idea: Oscillations of sky scrapers during wind storms. From external to internal support structure.
Usually papers don't have very intuitive math due to how many layers the information is on top of. What I think might be helpful is use the force diagram and simulate how it changes with each time frame. That might be a good place to start
I’ve demystified the math here:
czcams.com/video/4er2buINHF0/video.htmlsi=dPlL8yD0K1UL-7lI
Steve - huge fan of your videos. The discussion around intuition is great. If you stripe the ball with a few colors, it would be most helpful to see the how the axis of rotation is influenced by the wall and rolling.
Yes I want to see more with the motion amplification camera! I can think of so many industries and application where that could be extremely useful!
How about a motion amplification of a city skyline or a very tall building district during a wind storm? It would be neat to actually see a building with a tuned mass dampener next to one without!
Steve is the only person that can actually make me want to learn something I don’t need
sounds kinda similar to school, except there they make you not want to learn anything
ever played beerpong?
Oh wow, you my friend are in for a loooooooong weekend when you discover Wikipedia
@SteveMould, did you try applying the equations of orbital mechanics to it? Orbits are mathematically just sections of a cylinder. The motion of the ball looks a lot like a precessing orbital plane. The ball shooting out occurs when the trajectory matches e>1, which is what we use to slingshot spacecraft around planets.
Top notch work and easy to understand presentations.
I love following Steve on his journey from bewildering phenomenon to intuitive understanding.
Edit: Didn't realize he was going to mention it during the video. Just recognized it
I'm sat here trying to figure out why he still has the ball from an old mouse to hand?
Minute amplification ideas: Bathrooms - curious to see how well built a bathroom is - turn on the water and see if there are any movements in the shower/bath. Cars, the car itself and the engine compartment - how does a car vibrate? Nailing up a picture on the wall - sometimes when you nail up a picture, you might popout an old drywall nail; would be interesting to see what vibrations are caused when nailing on a wall. Similarly, jumping on a 2nd story house - the other day my daughter started jumping with joy and I could feel the house framing move as we were on the 2nd floor.
This reminds me of throwing a tennis ball against the rear of my childhood house, my father asked me to stop and showed me how the opposite end of the front of the house, wood siding nails were loosening.
The behavior reminds me of a ball rolling into and out of a bowl. If it retains enough momentum, it'll pop back out; if not, it stays in the bowl, just rolling back and forth like a pendulum. I think you already gave us an intuitive explanation - the forward momentum leads the ball into the cylinder, the gyroscopic effect wants to roll the ball back out, the frictional force direction keeps changing in relation to the gyroscopic direction, and the three start negotiating with one another. Given enough momentum and a friendly angle, the resulting path begins oscillating between downward and upward. Great video!
Medhi recently made a video with aluminum foil balls, where he could have used the RDI technology, to see the small movements of the balls. You two should make a follow up video together about the phenomenon! I would love to watch it happen!
I wonder if you could develop some little magnetic "kicker" to give a tiny bit of energy at the bottom of its oscillation, to keep it going indefinitely, similar to those kinetic magnetic desk toys. I would absolutely love to have something like that as a desk toy.
there's a seller
Could work with a lighter ball(table tennis ball?) and a fan. The fan makes a vortex so the ball keep spinning, airflow upwards cancels out gravity.
@@m8ejust gotta keep the momentum going so it keeps spinning as well
The big version shown in the video moves fast enough already. A desk toy sized one would move too fast to admire and wouldn't look *cool*
It might be possible if we put the motor inside the ball (similar to electronic bablade)and power it through induction.
The idea for motion amplification is "How a transformer emit a high-pitched sound?" (if it can register such high frequencies). It might be quite interesting because AFAIK it's because a transformer physically changes its shape due to the magnetostriction effect on the transformer's core.
50-60 hz base high frequency?
@@2adamast I had in mind the high pitch that sometimes comes from phone charger or other electronics (it usually operates on much higher frequencies). But you're right, it can also be a low hum when it's directly connected to the outlet.
I have a possible idea for your motion amplification camera. There are many educational videos on simple DC motors, where a loop of insulated wire is set in a magnetic field, held by paperclips at either end (which are taped to a battery) , and so a current is passed through the wire. Most of the videos state that you should sand off all of the insulation on one axle (end sticking out of the of insulated wire coil) and only sand off half of the insulation on the other wire, is an orientation 90 degrees to the coil plane so you've made an intermittent commutator. But in one video they sanded all of the insulation off of both wire ends. I tried both methods and they both work, but seemed different The completely sanded one didn't work sometimes, but seemed to have more force holding it still. Other times it spun around like the half-sanded one. I think the sanded wire through the loop in the paperclip stand might start to vibrate at a frequency sympathetic to the effective coil rotation.
one of the best channel on this platform, ever. Thank you again!
I think it would be helpful to track where the ball is in contact with the cylinder, and then draw/animate that path along the surface of the ball. It's not just rolling along a circular path along the circumference, and I think understanding that is important for an intuitive understanding. Also if you put markings on the ball so we can clearly see how it is actually oriented, that would help to understand/visualize what's goin on.
Yepp
@@JokeswithMitochondria your username intrigued my curiosity so I went to your profile. Your entire channel is mood Imao
I'm curious about how that would trace in a hypothetical situation without gravity or friction. Would it make circuits around an ellipse? Would it gradually level out until it's moving around a circle? How does this behave if you isolate variables and change them one at a time?
I think from its perspective, the ball is simply traveling in a straight, 2 dimensional line.
Cutting the tube open to rectangular shape should help visualize this.
It doesn’t hit bottom part because the angle doesn’t allow it to, like shooting a cue ball through narrow space. It travels in a straight line as far as the angle allows, then it hits imaginary rectangle and bounce back.
A good start to this would be to simply draw some stripes on the ball. Some design that would allow you to 'see' the spin with a high speed camera.
3:34 Have you considered spraying a hollow ball with something like Testors Dulcoate? Magicians sometimes use it on playing cards to increase friction between two cards. Great video, as always.
Hey Steve... Even though I don't play squash myself, I understand there are different grades of balls for 'Speed' and those graded balls react differently during the game of squash, as in, as they warm up with the constant hitting of rackets and the wall, they change their perameters of bounce etc... So.. Would different temperatures of the squash ball make a difference in 'Slippage'/grip when performing these tests within the perspex tube and thus adjust the ratio of rotation vs raising & lowering in height? ie a warm/hot squash ball vs cold??? 🤔😏
😎🇬🇧
I can explain this rather easily, I think.
The key to understanding what is happening between the ball and cylinder is in analyzing the relative motion of the core of the ball vs. the outside of the ball vs. the cylinder wall.
Like a continuously-variable transmission, the pathway of contact determines the speed at which the ball rotates vs. the speed the center of the ball travels across the inside of the cylinder.
From the balls' frame of reference, its pathway through the cylinder is no different than it would be through a cone.
As the ball reaches a point in the pathway around the inside of the cylinder where it is spinning on a shorter line of longitude, the actual speed of the ball as it travels across the cylinder is at its lowest. Then as the inertia of the ball continues to push it around the cylinder, the longitude of the contact line on the ball grows larger, allowing more of the inertia stored up on the way down to be released into the cylinder wall, which in turn decreases the speed at which the ball is rotating while increasing the speed at which it is revolving around the center of an elliptic section of the cylinder. This increase in speed results in an increase in centrifugal force, which flings the ball *upward* because the downward direction was where it gathered the momentum.
I've heard that up to 80% of the noise a passenger jet makes while in flight is fuselage/wing vibrations. I imagine this would be a massive task to turn into a video, but I think it could be incredibly cool.
long cardboard box + 3D printed plane + EDF (or any other fan, but I like electronic ducted fans because they're absurdly powerful) 👀
I've never heard of a motion amplification camera but now I need one! I'd love to see musical instruments, such as guitar strings, drum heads, or even brass instruments!
a guitar string lit by a CRT TV can be quite a sight... strobe lights also do nicely and aren't difficult to achieve with LEDs
I've seen a few guitar string recordings by what I think were motion amplification cameras before. It was really cool.
I wrote basically an essay here just a second ago but I figured I would explain this more Layman's terms.
- Ignore gravity so you can see this change to the extreme
- ignore the gripping factor, this is taking into account sliding which ignores the force of friction.
- Now what you want to know is why it takes this trajectory, we will look at its angular momentum vector in order to see this clearly and make the trajectory horizontal.
Like this
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The area you see here is the trajectory (x axis) and angular momentum vector (y axis.) This vertical line basically just shows the angle that the ball is rotating (think of it as a pen and the ball is spinning around the pen with the pen being the center of the ball). For this angle to change, there needs to be a force which overrides the force holding it upright.
We said gravity = 0 before, now lets say the force of gravity increases based on earth. This means f=m*a , on earth (a) doesnt change. So you can only change mass. Considering this, the more mass the larger the force of gravity. Considering the ball is thrown at an angle, then your visual diagram would have a gravity force that is not in the opposite direction of the angular momentum direction, but at an angle like so
Like this
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Steve, I really really love your videos. It’s so interesting because you don’t just bore us with math and physics (although infinite those quite interesting), but you take us through your whole thought process and your initial ideas on how it might work. Keep it up!
He gives good explanations on the intuition behind it
id like to see a motion amplification video of a jackhammer, where something is actually intended to break, to see if it can predict where stuff breaks
Per your request, here is an attempt at a simple intuitive explanation of why the ball's vertical travel oscillates at a ratio lower than once for every circuit of the cylinder, the value obtained if the axis of rotation remains fixed.
(IDK whether a better explanation has already been posted.):
The ball initially enters the cylinder rolling at a downward angle. It has a downward velocity and its initial axis of rotation is at an angle to the vertical. Assume for the moment its axis of rotation stays fixed, and there is no slipping. A quarter of the way around the cylinder the ball's trajectory will be horizontal. Its downward velocity will have changed to zero.
One can think of the downward velocity change as resulting from a force applied perpendicular to the ball's trajectory and acting on a tangent to the ball's surface at the point where it contacts the cylinder. That force bends the ball's trajectory. But being tangent to the surface, it also affects the ball's axis of rotation. (The direction of axis change is per the gyroscope effect.) Because some of the force is spent changing the axis of rotation, less remains to bend the trajectory. So the trajectory changes more slowly than it would otherwise. When the trajectory changes more slowly, the oscillation ratio is lowered.
Hence the oscillation ratio is lower than the 1:1 obtained if the axis of rotation did not change.
I would love to see the high speed camera applied to both the ball and club of a golfing tee-off. Great video as always Steve!
This reminds me of what happens sometimes in basketball where the equator of basketball gets really low on the rim but then the ball pops out anyway. Once I saw the ball go around the rim about 3 times before falling out instead of going through the hole.
This might have more to do with the "applied" backspin from shooting the ball, but without a mechanism to launch the ball exactly the same into the cylinder each time there's going to be inadvertent spin added each time.
in terms of the motion amplification camera, i'd love to see ordinary everyday things that people might have at home using it, things like laptops, fans, printer, computer/tv speakers, faucet/tap, kitchen/bathroom pipes, washing machine, microwave, refrigerator, etc. Would be nice to know how much these types of things move over time, what parts may need replacing or something you think should move doesn't move at all
6:56 is going to revolutionary I'm a structual welder and I go to all types of different shutdown around the US for huge industrial power plants and of all the inspections we do like X-rays, we basically mainly check the areas where we know there is vibrations. I would love to see minute vibrations of how a welding machine like a Miller or Lincoln Electric or even a small horsepower engine. Large production factories mount those welding machine onto the structural supports and I've always wondered how much of a causation it has to the beams
Awesome video!
Try using mirrors if you're having single cam problems. Worked great for us!
Could you possibly use your motion amplification camera on a roadway bridge? Not sure what the lenses & technology allow, but it'd be cool to see a suspension bridge, or even just a standard concrete overpass flex as cars go over.
I was thinking this too! A bridge would be really cool to see
I'd be curious to see the difference in vibration management between older bridges and newer ones if it was possible. Maybe even more modern earthquake resistant bridges and structures.
Our CEO took this bridge video a few years ago! czcams.com/video/YLlwqJTWp5c/video.html Makes you think..
Doing it with people walking across smaller pedestrian bridges would be interesting to see as well.
Happens with basketball hoops as well, though I’m guessing spin and physical grip has more to do with it in that case.
Bingo
Also, the point of contact of the basketball on the rim is different than in the examples here. Flipping the point of reference, it's almost like the cylinder(rim) is spinning around the ball
Based on your explanation and the slow motion footage, the best way I think I could explain it is similar to your explanation. As you throw the ball into the cylinder, it'll instantly encounter friction against the wall of the cylinder and begin rolling in the direction you threw it. But then, due to the curvature of the cylinder, it'll "roll" (actually slipping) around to the other side, and with your same naive assumption that the axis of rotation stays the same, the ball's original rolling rotation will now be rolling against the direction of its movement and start rolling back up the cylinder.
One experiment that might be an extreme example of this is throwing a bouncy ball under a table. You might have done a video on this before, but if you throw a bouncy ball under a table, it'll hit the floor and begin spinning forward. Then as it bounces up, still spinning forward, it hits the underside of the table and instantly gets thrown back out from under the table in the direction you threw it because the forward spin hitting the table produces a backwards frictional force that causes it to bounce back. At least that's how I understand it and it seems like an extreme version of a cylinder. With the cylinder, you then have to account for the spin of the ball constantly trying to match the direction of the ball's tangential movement along the cylinder walls.
I hadn't actually thought about this, having only played a few rounds of mini-golf in my life, but it makes sense, within a certain range of parameters.
Without watching more than 5 seconds of the video, what is obvious is that you are getting rotational force input from two different fixed directions but you can only actually rotate in one direction, so since one of the forces is an exponentally decaying linear input and the other is an accelerating quadratic input, the rotation is unstable and must flip, and since flipping is symmetrical and cylindrical holes are symmetrical, there are necessarily cases where the ball just pops back out.
Neat!
I'd love to see the motion camera filming various types of bridges such as suspension bridges and cantilever bridges. There are three different bridge types where I live and I've noticed, during rush hour commute, that when I put my foot down (on my motorcycle) that the cantilever bridge I cross bounces imperceptibly.
... bounces perceptibly.
If imperceptible, you wouldn't be able to feel the vibrations when you put your foot down.
And yeah, I'd like to see bridges' vibration patterns too.
I second this notion
I first this notion.@@Jeep_God1998
*bounces imperceptibly to the naked eye@@GregConquest
huh, I've noticed that too. There's a road where I live where one direction of traffic crosses the river on a steel truss bridge, and the other direction crosses on a concrete slab bridge, and I can definitely feel movement if I stop on the steel one. It's a little alarming at times, especially since I know that bridge is pretty old.
We had a similar problem in our lab where we needed 2 slow motion cameras (we didn't) so we used a tilted mirror. It worked. Nice video
Here is how I think about it intuitively after reading those papers:
When the ball touches the cylinder the normal vector points out perpindicular to the cylindrical surface, through the ball on the other side.
---- This means that there is a uniform horizontal revolution on the ball that acts based on the intertia and good friction of the surface with the ball
---- ---- Similar to just a ball spinning in a wheel [shake the wheel to spin the ball around in a circular motion parallel to cylinder's perpindicular cross-section (a circle)]
There is another factor included with this ball that makes it different from the horizontal spinning ball: the vertical inertia
---- The vertical inertia component of the ball (parallel to the cylinder) forces a counteracting force called a euler force
---- ---- The same force you feel when an instantaneous rotational acceleration is applied (i.e. falling backwards while the carousel starts or the instantaneous rotational change of this ball)
---- ---- This depends on how far you are from the center of spin: the ball will spin more on the outside than the inside (closer to the center).
---- The cylinder contact with the ball makes the ball want to stop bc of overall inertia (this is where Euler's force comes in)
The Rotational pole the ball obtains changes over time because of the vertical force on the side of the cylinder
---- for anyone who is having trouble understanding this here is a video for the intuition behind the changing of the rotational pole: czcams.com/video/n5bKzBZ7XuM/video.html
---- ---- and to connect the dots the edge of the cylinder(vertical force) and euler's force counteracting acts as the forces described in the video which change the poles of the gyroscope
everything else you have said seems intuitively true the pole mostly maintains itself because the ball has an inertia for that spin that it obtained in the first place but the pole also changes over time and I think this is why...
I appreciated you looking over this topic it was very interesting. I'm glad there are more physics phenomina out there than I could imagine. If you see this, feel free to let me know what you think about this explanation... I might have done it poorly but hopefully it will give you some more ideas about how to think about it intuitively.
I'm subscribing for the motion amplification videos!
Hard drives vibrating can be a problem in server settings (hence the need for server grade hard drives). Could be interesting to see how much they actually vibrate :)
Would motion amplication show much much they vibrate? I thought it would just highlight the parts that are moving?
Put a mirror over the cylinder?
This way the camera sees both
That's a really good suggestion
@@SteveMouldor maybe under the cylinder standing on a transparent table. Less chance of breaking a mirror with a mouse ball ^^
Hah was typing up this same reply then thought "should just ctrl-F 'mirror' first" - turns out we Mould viewers are all similarly resourceful!
Hi, great viedeo as always!
For your camera: Some times, when I stand at a traffic light on my bicycle or even sitting in a car, and a truck drives by on the other lane, I think I can feel a faint shaking of the ground. (But I don't know if this is just the air pushed sideways by the truck instead.)
Would it be possible to film a road with this move-amplifing camera and see the ground shacke because of the traffic?
If you ever need 2 high speed cameras you can always use a mirror ;) saves me loads of money.
Motion amplification idea: Saxophone. I play bari sax, and I can feel the instrument vibrating differently as I change the notes, especially in the lower register. I assume there are nodes along the brass. I would love to see that!
Oh of course, any instrument would be really cool to see!
As the ball moves across the surface of the cylinder, the part(chord) of the ball that contacts the wall changes. This changes the relative direction of rotation, pulling the ball in a new direction.
If it were rolling inside a hollow sphere, the ball would settle into a more or less stable “orbit” until parasitic forces decay the motion, but on a cylinder it is less stable because of the variable curvature of the ‘orbit.’ This also accounts for the more aggressive procession.
la bola la puedes fabricar usando cualquier bola hueca y la cubres con una capa de un producto poliuretano de nombre sikaflex....lo dejas secar y luego la pules redonda...es fuerte para pulir pero se puede..
You can make the ball using any hollow ball and cover it with a layer of a polyurethane product called sikaflex... you let it dry and then polish it round... it is strong for pulish but it can be done...
it will be cool to observe the oscillations of grandstands at a football (UK term) match.
Having a visual of the dynamic loading will be interesting to see
Using Motion Amplification in a stadium is a great idea! So much movement to see!
I feel like with a specifically marked ball and a fast enough camera you'd be able to plot the exact movement of the ball itself and extrapolate from that. Get Gav and Dan in here
For the motion amplification, a really good use would be cardiac physiology. Highlight things like the subtle motion of the cardiac apex under the chest wall or even better, the dreaded waves of the carotid pulse.
Another fantastic idea. As a retired physician I could see both general interest and a potential clinical application!
This is my first visit to this channel. Am I the only one who's totally enamored with his background composition and colors when he's in frame?
That motion amplification camera is so cool, never thought of one being a thing, but sounds super useful!
I would be curious to see the affects of sound waves (Or different frequencies) has on objects. Maybe to demonstate a resonant frequency?
That's a super neat idea! Would be very interested in that, myself.
Hi Steve ! IDEA I would love to see : motion amplification of the modes of vibration of a guitar top, a little bit like Chladni patterns. And then try other kinds of instruments to see how they behave differently.
Sound boards and drum skins would be cool. Especially in reference to the notes being played.
I was thinking looking at what happens at the nut and bridge/saddles perhaps on electric guitars and see what the vibrational relations between the body and strings is.
It's kind of like when you bounce a basketball forward with a reverse spin on it and get it to bounce back into your hands. The forward momentum of the ball is shifted by the grip of the ball on the surface caused by its rotation.
When you launch this ball down into the cylinder, it picks up additional lateral spin more horizontal than the axis it had been rotating across (i.e., the angle of entry) because of the centrifugal motion of the ball around the cylinder. In other words, the ball wants to escape the rotation and is forced straight out in a horizontal direction by the centrifugal force, causing it to make contact with a different (higher) place on the surface and then to roll along that higher plane. As that horizontal spin works on the ball to translate into lateral motion because of friction, the ball's course is altered with its new spin. These two forces, the spin momentum and the revolving momentum, work in tandem to shift the direction of the ball's motion. At either end of the oscillation, the angle has become flat and the spin is sufficient to divert the ball's course. Of course, nothing different is happening at these points at the extremes of the oscillation. The ball was always shifting course as soon as friction on the cylindrical surface caused its momentum to translate into a slight direction change toward horizontal.
At the midpoint, when the ball's rotation is in direct line with the angle of travel, it is traveling at at angle to the curved surface, destined for the cylinder to once again bend its path to the horizontal.
To illustrate this, I believe a tetherball's path around a pole would become more horizontal as it wraps the pole: the tighter the turn, the more contained the momentum, the more relative force converted into lateral motion.
I think I have an intuitive way of understanding this. As you already mentioned, mathematicaly, this could go on forever if not for loss of energy through air friction, etc. Lets imagine we would try to introduce energy by moving the cylinder in a circular motion, just like we all did as kids :) As you might now from experience, if we move the cylinder really hard/fast, the ball will go very fast in(to) a path of the smallest possible circumference (perfect circle, instead of an oval) within the tube and move on this line until we stop moving the cylinder.
As you said, gravity does not have an impact as we can turn the cylinder in any direction without the ball changing its path, given we manage to keep the perfekt rotational movement of the cylinder.
This means that the ball is always being "pulled" on this line/path of least resistance. The harder we move the cylinder the harder the ball is pulled onto this line.
So when you throw the ball into the cylinder, the ball immediatley starts being pulled towards this line by its centripital force. Looking at the thumbnail of this video, the ball at the lowest point at the path represents the moment when the ball is in fact on this line. However, as it still carries momentum from the acceleration towords this line it overshoots it with a certain excess of force now opposite to the initial direction. Therefore the ball moves beyond the line and doing so the centripital force now works against the current direction, which results in a gradual change of direction.
At the midpoint/crossing of the overallpath the ball now has a new optimal line within the cylinder, opposite to the below one with the same distance to the crossing in the middle, as the movement direction of the ball is inverted. Now the same happens again just mirrored. After this the cycle repeats.
If we would be able to move the cylinder in this circular way and therby apply just the perfect amount of energy, we could keep this going on forever. If we rotate to hard, the ball starts moving in a perfect circle. Too little and it drops.
Even though I did not include any other phenomena which happen at the same time like the rotation around its axis, I hope this makes somewhat sense😅
For the camera motion amplification, id suggest filming the processes of cnc or manual machinery. Theres alot of complications when it comes to cutting metal.
Maybe do a collaboration with a machine shop and see how much the tooling or metal flexes during a milling operation.
@@maxximumb Exactly what I was thinking! If the camera was developed for industrial applications in mind, it would be mesmerizing to see the subtle flexes and chatter!
All of your topics are always fascinating! Your demonstrations are great, and your presentation style is always engaging! Bravo!
It looks like the ball is traveling on a wave wrapped around the cylinder. And the ball changes directions due to a combination of a peak in relative g force, and curvature that then with friction carries the ball up. The curvature seems to be acting like a catalyst by causing the ball to slow is decent into the cylinder by changing the g force and gently moving its angular momentum up, and then in tandem with appropriate friction, speed, and ball squishyness (which probably helps with friction), the ball starts to stick its way up the cylinder to complete the wave with whatever energy it has left. (Basically the curving cylinder seems to be changing the acceleration down by slowing it, but also the curving increases friction by g force, but then the speed is at its peak at the bottem of the wave and with all this extra friction/grip/GeForce, speed and a decreasing acceleration down into the cylinder, AND the cylinder still being cylindrical the speed with all the other stuff mention it's able to climb out/up. I'd imagine it's how when race cars turn they can turn easier when the track turns/banks inside the curve, it let's them hit faster speeds at sharper angles.
Hey! A billard-cue hitting the cueball looks awesome in slowmo.
Also a pickup on an vinyl LP is pretty cool!
I would love to see the motion amplification pointed at some electronics or a PC's internals. Something we think of as being completely still when in operation. Would be amazing to see if there was some vibrations.
You would only see motion in a few components, mainly Relays, Hard drives, and things that are designed to move. Everything else is just chemistry, electricity messing with the conductivity of silicon to move other electricity around (these are called Solid State components, because they are completely solid. There are exactly zero moving parts.). Hard drives have magnetic disks inside that spin really fast and store the data, relays are mechanical switches that click on or off based on electricity, and you know what a motor does. That doesn't mean that like the wind or the desk wouldn't be moving though.
@@serphorus Ever hear of coil whine? How about transformers humming when under load? Listen to a microwave oven while it's running. That hum you will hear comes from the transformer that provides the high voltage to the magnetron. Sometimes things that aren't "designed to move" as you say, do in fact move a little bit.
As always, I enjoy seeing your videos and detailed explanations. Thanks for that!
Regarding the fact that you have only one high-speed camera, using mirrors you can create a "split screen" which will allow you to see both the side view and the top view in the same frame.
Absolutely the amplification of vibration videos sound super interesting.
its easy to think a constant force means constant rate of precession, but not so, it has to accelerate, in steady state yes a constant force means constant precession to maintain conservation of angular momentum, but when it is changing its a bit different, that is where the delay in the non slip case comes from i think. when you arrive at the bottom you have the maximum rate of precession steering upward but 0 rate of change in the rate of precession plus the change in rate of precession from gravity it the rate of change of precession from gravity is always just depending on the angle between the vertical and the direction of motion inside the cylinder, its maximal when the ball rolls fast and the angle is flat and parallel with the circular direction, but at some speed and downward trajectory the delayed rate of precession when you reach parallel trajectory tangent with the circular horizontal direction it is smaller than the upward steering change in precession causing a decrease in the steephood of the trajectory eventually leading to the ball going up again. roughly speaking. i think the intuitive hurdle is basically too get this idea of a torque on a gyro leading to a specific rate of precession out of your head and relearn what happens to a gyro when a torque is applied. you can solve it exactly for the case with no gravity and then think of the height as a change between different solutions to the no external force problem. so as you go down in the potential its a continous transformation into instantanious parts of different non external force solutions. not very intuetive perhaps but its real and true. then the moment of inerta and the hight determines the speed at soem height, and the speed gives you a trajectory for an orbit without any force correpsonding to a small change, like gravity only acted for a breif moment and changed one no external force solution into another non external force solution with the same angles and speed at that point to as you go down it corresponds to the same angle solutions with more velocity and angular momentum correpsonding to different derrivatives, and so you can derrive a change in the changes and get ready to do some crazy maths lol :P. sorry for typos or mistakes.
Awesome video! I love how you depicted the mental progression towards a hand wavey model (and I totally buy the hand wavey model you came up with!) gotta send this to my mom who golfs a lot…
To augment the hand-wavy model, you can consider how the axis of rotation will pivot as a result of the friction force from the wall. You can see animations and an explanation of this here: czcams.com/video/4er2buINHF0/video.htmlsi=dPlL8yD0K1UL-7lI
On the matter of viewing the setup from two different angles simultaneously, you could probably pull this off using mirrors to reflect the two perspectives into the field-of-view of a single high speed camera. I haven't taken the time to figure out the specifics (something like the mirror arrangement used by Newtonian telescopes perhaps? Maybe incorporating a second arrangement of mirrors like a periscope to first shift the light's path to the side so that you needn't reflect through the cylinder itself?), but it ought to be possible.
Once you commented on the density of the inner sphere of the mouse ball, I couldn't stay focused as my mind instantly began shooting out ideas.
I began thinking about huge acrylic cylinders with beach-ball sized foam filled balls with an ultra-dense material like tungsten forming a very tightly condensed inner sphere.
Or once the mathematical formulas have been worked out, putting the material of a neutron star as an inner sphere into the gravity well shaped cylinder... Damn, you really might be onto something here. Sadly, both my understanding of physics and math suck so badly I couldn't assist in either way, except providing strange ideas once it was conveyed to me in an interesting but simple enough way.
I'm not sure if this is a valid comparison, but the first thing that came to my mind was a car on a banked curve: if the car goes around the banked curved too quickly it moves outward (away from the center of the circle) and if too slowly it moves inward (towards the center of the circle). Since the ball is constricted by the cylinder's walls, the only way to go "away" is to go up the cylinder's wall and "towards" would be down the cylinder's wall.
When the ball is first thrown into the cylinder, it's moving too quickly and even though it's thrown downward, it'll start to rise up due to the extra speed. As it does this, it will slow down causing it to move back down. I think this makes the bank angle of the track equivalent to the angle you throw the ball into cylinder (not sure though).
This theory does not explain the sqrt(7/2) phenomenon (though it might if analyzed more mathematically incorporating the moment of inertia).
There is a critical speed for the car on the banked hill problem that doesn't require any friction to complete the turn. If this theory is right, there should be an analogous situation for the ball in the cylinder: turn the cylinder horizontally and if you throw the ball at just the right speed for a given angle, it should show minimal to zero deviation horizontally and more or less stay inside the cylinder. I think.
You always impress me with your desire/ability to explain things intuitively. I am a firm believer in understanding things like how you explained this effect in this video. Great work!
I think most people have what I've called pseudo learning. Just because they can parrot some mathematical formula, they think they understand the topic.