250,000 DOMINOES! - The American Domino Record - Smarter Every Day 178 

It was so great to have you here at the Incredible Science Machine!! You brought so much energy to the team! Thanks for highlighting our event and doing this study - it was super fascinating to watch :) This is exactly what I would have predicted: the bottom of the domino slips backwards more on surfaces with less friction and the domino line topples faster. I did my AP physics project on a similar concept and found that a smaller spacing on sandpaper (frictional surface) was SLOWER than a large spacing on sandpaper. What's interesting is that my original hypothesis was the exact opposite. From experience, usually a larger spacing is slightly slower on a normal wooden floor, but I didn't account for the floor surface when I made my hypothesis. A slippery floor surface (and also domino material, hence the color to speed variation) such as glass makes the dominoes fall faster. You're right though that this is more complicated than we think, and having an unexplored area of domino physics is super exciting :) Can't wait to see what you discover in the next experiment! Also a suggestion for starting the dominoes... I feel like we need some sort of motorized toppler that very, very slowly moves forward hitting the center of the first domino near the top. If you use a small spacing, the first domino may just lean against the next domino and not topple right away, but this would allow the bare minimum force required to topple the line. You're also right that a longer line is necessary so that the speed of the dominoes can reach terminal velocity. I'm not 100% sure how many dominoes that is (this could also vary with spacing), but I'd recommend maybe 50 in the line to be safe. Thanks again for coming! And now to watch the behind the scenes :D

It is not too hard Mr. Smarter. Put like 1 meter of the domino train length outside the camera range and run some additional length of it in front of the camera. So dominos have time to do all acceleration and effect of you triggering it will be gone by the time the dominos reach in front of the camera, in steady state. Then you can consistently measure the speed of different material and colors.

Fire a .22 at a prince Rupert's drop and let the exploding fragment knock over the first dominos.

That “wait a second, we’re doing this wrong” moment-that is why we need to advocate for scientific experimentation. We need more people to look at the world and think “hmm, that’s odd.”

Trigger the initial domino by using a Newton's cradle, but just use one ball, at a consistent height. Modify cradle as needed. An even simpler way to say it: use a pendulum. Adjust the pendulum to just nick the top of the 1st domino. If you're really good: adjust the mass, and impact point of the pendulum to match the equilibrium state of falling dominoes, e.g. after 20 dominoes in your video. I'm sure this will get lost in the comments though.

10:26 - „There’s a lot more Greek letters in the math now!“ …what an accurate statement xD

I love how your daughter immediately goes back to standing on the left, and then on top of that, repeatedly sticks her tongue out at you. I love even more that you undoubtedly saw that and left it in while editing anyway. Had me laughing super hard.

Create a long string of dominoes and only measure the steady state ones at the end. That way they're triggered off a previous hit which is more like the real scenario (human trigger is the first hit but dominoes are the trigger for the next thousands of hits). I work in vibration analysis so you could approach the timing measurement with a microphone and catch the clicks of each hit and convert it into a frequency with great accuracy. An accelerometer on the table might pick it up too. And we use acquisition software from a company called LMS. It would give you actual data and numbers to go with your great footage.

A random, ghetto, off the top of my head idea is to eject an external cd drive, and have the tray hit the dominos. Might be a bit fast though, but it could be consistent.

The guy with the blue hair... Well that's ME! :D It was so awesome being part of the building team this year :) ♡

I want to eat the thumbnail for some reason...

Something you don't seem to be considering about those plastic dominoes is handling. The oil from your hands builds up over time the more they're handled/used. Maybe they should all be washed before a new round of tests and clean gloves used to handle them? Or, the difference the hand sweat makes could be so minimal as to not matter? But, if you set up pieces that have been used a multitude of times next to brand new first time used pieces, the newer ones would likely slip on the surface easier than the older ones. The tipping start: A swinging weight that hits the first domino the same way each time. Locked in place with a release that doesn't propel or hamper the weight. Hope this helps. Maybe you'll come up with something else from reading this. As always, have fun! It's science!

Small rebellion on your daughter's part at the beginning made me laugh out loud :p

Thanks for featuring my event in your video! It was awesome being part of this experiment!

It’s simple. It can be explained by the conservation of momentum. The reason why ‘slipping’ ‘increases the speed’ is because when it pivots on it’s centre of mass, there is a smaller moment of inertia, therefore it can rotate faster and displace the next domino quicker, even though the clear domino’s have a slightly higher mass. It’s like a figure skater spinning with her arms open vs arms closed. She can spin a lot faster with her arms closed because she has a smaller moment of inertia in that instance.

Take a servo motor and a micro controller (like an Arduino) and fix the location of the servo motor. In most cases a servo motor comes with rotors you can put on top of the servo easily. You can modify the rotor to fit your needs, but it is not necessary in our setup.

0:14 savage kid

Trigger- Miniature linear actuator! consistent variable speed push :)

So cool! I've watched a lot of Flippy Cat's domino videos too!

As the trigger mechanism, if you place some sort of weight on a string creating a pendulum, with the axis directly above where you plan the first domino to be, you can raise the pendulum to a consistent height ensuring the potential energy going into the system is the same every time.

Use a pendulum held by an electromagnet released by termination of the power source. This should create consistent release every time.

0:14 ya got a little rebel there. haha

Hey Destin - a couple thoughts on your domino experiments: 1. I wouldn't worry about your initial tipping mechanism. As long as you have enough dominoes to get to steady-state, the initial push shouldn't change much. 2. If you don't worry about the initial push, the only thing you can't do is a "race" between two types of dominoes like you did in this video. But it was a little difficult to see. You can probably make up the difference in post by aligning two different runs top and bottom to get the same effect. 3. More slippery domino or surface means less friction, which should make the domino fall faster because the friction with the ground works against the direction of rotation, making them rotate and fall more slowly. 4. That being said, the dominoes with more friction should fall further forward for the same reason, allowing the grippy dominoes to be spaced even further apart, (slowing them down even more?). You saw the opposite in your tests so far, but that may have to do with how close the dominoes are spaced - if they are too close for this effect to matter, the more slippery dominoes may end up falling "further" because when the last one or two get "squished out" at the end of the drop, they can slide further before stopping. This may mean the speed difference between high and low friction also depends a lot on spacing. 5. I feel like heavier/lighter dominoes shouldn't play a huge roll. Think of the effect of dropping a heavy and light ball of the same size (Veritasium has some great videos on this). They end up falling at the same rate. But we're not dealing with spheres here, so it's possible rotational inertia has some different effects, and my instinct is way off. Great work!

use a servo (or similar) to push a pin or rod. that way the speed and force are consistent every time. also I think it would be interesting to use metal dominos to test the weight theory. then you could race the normal plastic dominos against the metal ones to get, a possibly, much clearer result. another thing that might be done is to have some metal ones with a matte finish and others with a polished finish. but the finishes may be taking it too far.. just the drastic weight difference will be enough to make it interesting.

Use a stepper motor to topple the dominoes the same way every time!

Hey Destin, I work at a cafe and have been wondering something for a long time. I've noticed that when I begin to steam milk or water for people's drinks, that the pitch starts off high, and then as the liquid gets warmer, the pitch drops; and as the boiling point approaches, the pitch almost disappears altogether. You can also hear this when you turn on the hot side of your bathtub faucet, the sound of the water will lower in pitch. I'm wondering if this is due to energy transfer, and as the boiling point approaches, the amount of energy able to be put into the system is reduced. I know as things get warmer the molecules get really excited and full of energy, but I'm wondering if this is the actual cause, or if I'm way off the mark. I know it's probably not anything to make a video about, but I do wonder if you ever noticed the pitch change as liquids warm up? And what is the cause? Keep making amazing and interesting videos! All the best to you and your lovely family, ~Pete

Hi! Thanks for the great video once again! As a solution for starting the domino fall, I thought about using a motor, maybe a stepping motor / servo motor that you can rotate really slow and just for one turn. Attach a wheel to it and and off center shaft that acts like a pushrod just like in a simple piston engine. You could easily adjust the height at which it pushes the dominos and also the distance how long it pushes the domino. It would always push the same speed/spot if you align it with the tool that you use to build the line of dominoes. I think that would be a good solution for getting reliable results in future experiments. Looking forward to see the video!

Destin a doorbell solenoid. It can be mounted at a set height, the stacking jig can be at a set distance, and so long as you have a consistent power supply it will exert the same amount of force everytime.

By the way, I see why the frictionless domino's fall faster. It's all about energy, and considering that it's a pivot; it to top portion is allowed to fall forwards and the bottom portion allowed to rise backwards at the same time(which is what ALL domino blocks want to do, regardless of friction), the energy will not be absorbed much at all until it hits the next block and transfers it's energy. But if we introduce friction on the bottom half of the domino, then the same motion will happen, but the upwards/backwards motion of the bottom part of the pivot (block) will be hampered by friction, which will absorb some of that energy, and actually counteract it, which means it takes the upper half of the pivot a little bit longer to hit the next block, as some of that forward momentum is gone. I wish I could draw a model, but that's at least part of what is happening.

use a small light pendulum and release it from the same point every time, using a marker, so that the bob hits the domino when at mean position.

This might be your best video yet ! Your "eureka" moment was awsome. In addition to the base friction though, something that I didn't see mentioned is that the friction of domino against domino is going to matter too. Rougher dominos will have more friction between them as they fall than slick dominos. This may also affect the base slipping. And for triggering I thought why not just use a small arm on a servo mounted in a fixed position relative to the first domino.

I'm excited about seeing the new logo!!!

Use a servo with a servo tester to trigger it. If you reset it, set it to the desired angle, and then power it, you should get the same speed everytime.

Do it with a servo and esc

Hi Destin, another great video - many thanks! Could I ask what sort of high speed camera you are using?

Awesome Videos as always. As a trigger mechanism I would recommend a high quality servo ( in order to provide the same force for all the tests) connected to an adruino.With this type of set up you can eliminate any torque "errors" because you hit the domino in the same spot.Also I would recommend the servo set up to be an alignment tool as well combined with the Domino set up tool. Thank you for the awesome Videos and keep up the good work :)

As far as a triggering method, a reliable one would be to have a pendulum-like trigger that can be set to a specific angle. (weight on a string pulled back to a 90-degree angle) Same fall distance, same force applied to the initial domino. Hopefully.

Anyone else notice his daughter in the background blatantly changing lanes? 0:17 Hilarious

This is just amazing. Thank your for this video:)

Destin: Stand on the right. Daughter:*decided to stand on the right and changes her mind*

I wouldn't personally make a special rig to push the Dominoes.The key point is to make the row longer enough, just so it is in steady state(since you pointed out initial acceleration increases).First you should determine the minimum domino number that cuts the mustard. Assuming heavier dominoes have more mass (and thus more energy storing potential), all you'll have to do is get the "transient domino length" for the heavier dominoes(steady-state length). And finally test all types with this length, and analyze just the steady state region.Since lower mass should mean less energy and consequently less "transient length", you should be covered.

To trigger it have a small ball on a slight ramp where you can put it at the top and let it hit the dominoes

"It's starts with one" (as the song says...) - first use only 1 domino brick, photograph it on different surfaces, getting hit at different heights, with different forces using a pendulum (as suggested by Miles Johnson). when you understand how 1 brick behave then you can move to more bricks at different spacing. I am enjoying your work so much - keep it up!!

Trigger method: Have a pendulum, bolted down to a stable surface, triggered by a quick release (potentially magnet) that is raised to a specific height. The height of the pendulum, and the mass of the pendulum would be the same, so it should exert a very similar force each time, with the only variable being air resistance changes, and position of first domino, which will be solved by next paragraph. Domino set-up: Use your measuring stick to mark specific lines on the surface, by which you will not only be able to place the dominoes in the exact same place for each fall, but be able to exactly measure the slippage amount. Camera set-up: The pendulum should trigger the initial block, and the camera focus should start at block 30, and from above, not the side. If you are indeed seeing that it takes 20+ dominoes to reach a stable fall speed. If the fall speed is consistent, then the rate of fall can be measured with differing systems. With the side camera set-up, you do not clearly get a view of the back row of dominoes, to compare velocities and times of impact.

Use a pendulum to trigger the dominoes, it should be the easiest way to get consistent force to trigger the fall. The more expensive way, but maybe a little bit more consistent would be stepper motors to push a slider I believe.

You can try using a pendulum to start the domino?

As for the speed in dependence of the friction coefficient: 1.) first ensure, that you change only the friction coefficient, and not the harness/sofness of the material. For example: Filth as a soft material will expand unter the toppling domino, applying more upward force to the lifting end of the domino, than a hard surface would do, that does not expand. 2.) What you effectively create with falling dominoes is a rotational-transitional wave. Its speed is would be defined by something that represents mass of the elements and something that represents coupling stiffness. a) Higher mass of the dominoes would slow down the wave speed (effect on the translational wave) b) Higher moment of inertia of the dominoes would slow down the wave speed (effect on the rotational part) Here the friction comes into play. A domino on high friction surface is pivoting around a point on the surface and therefore has a higher moment of inertia than a domino pivoting around its center of gravity (Parallel axis theorem). c) the coupling is highly nonlinear and can only roughly be compared to linear wave. A large spacing could be interpreted as "soft coupling" and therefore would lead to a slow wave. I guess spacings closed to the maximum possible spacing would be slower than medium spacings. On the other hand, a zero spacing would create an insane fast speed. The last domino would move instantaneously with the first one, but this would not be a chain reaction. 3.) For the spacing and speed we need to understand the effects that influence the wave speed, I would guess (in order of appearance): a) starting speed of the domino, given by pulse transfer from its predecessor b) reduction of speed by friction with its predecessor c) reduction of speed by lifting the domino slightly when pivoting around its front corner d) increasing rotational speed by gravity during falling e) overlayed decrease of horizontal speed as function of the cosine of the falling angle f) fraction of pulse that is transferred to the next one as function of its angle - lower horizontal pulse with larger falling angle - contact point hight defines how much of the puls is transferred as translational and as rotational pulse g) part of the overall length, that is covered by spaces and part, that is covered by domioes (which internally have an comparable infinite wave speed). The shorter the spacing, the shorter the effective "falling distance", and the lager the part with infinite speed. This could lead to totally different behaviours: * zero spacing: = zero falling distance, last domino drops instantly with the first one * very small spacing: triggered with minimum pulse, the first domino could already take (theoretically) an infinite time to just reach its highest point and remain on its (instable) equilibrium. This does not happen in praxis, but it shows, that there exist short spacings with pretty much zero speed. We even could think of a slightly larger spacing, where we just slightly overshoot this equilibrium and get just as much energy from the falling domino as to trigger the next one with the same minimum pulse. This would give a closed to zero speed chain. * increasing spacing would likely increase speed for a while to a maximumg * further increase of spacing would decrease speed, till we again reach a point, where the trigger puls is just enough to slightly overshoot the equilibrium, again a "closed to zero speed" chain.

Hi Destin big fan of SmarterEveryDay here. I have a hunch of using a graph of Coefficient of Friction vs. Time to prove if friction truly is helping to speed up the topple or slow it down. Also try triggering the fall in different areas of the dominoes e.g. In the CG, In the Upper surface, and etc. Thanks for the cool knowledge every video. :D Kudos!

you should use a pendulum and pull it back the same amount every time to start the dominoes

Smarter every..........midnight

Hi! Loved the video, and enjoyed wracking my brain around creating an experiment to get representative results. First, the question that originated the experiment will help to simplify some things. Since you are looking to see what factors impact steady state domino fall velocity, you should ignore data from however many dominoes it takes to reach steady state (in the video you said roughly 20) and the last few dominoes (since they don't fall on other dominoes in the same way the last 2-5 fall further and will skew your results). This first change helps your triggering issue because there should be convergence to a single steady state velocity when triggered at any speed below the steady state velocity, although if it still bothers you, you can achieve better precision with a pendulum with fixed starting height and mass. The second change is to alter only one parameter at a time to get the effect of that single parameter on velocity using a truth-table to construct your test cases (I assume you are already doing this, but didn't mention it in the video, so I thought I would add it). Lastly, I think it would add interest to mark out the center of gravity (on the side of each domino) so we can track the movement of the center as well as that of the leading edge (maybe easier to do that with a pen and jig rather than in video post-processing). Thanks!

Hi Destin, a couple of things: To consistently start the dominos, glue a small ball bearing to a thread to make a pendulum. Make a rig to suspend the pendulum above the first domino at a consistent height, with an electromagnet holding it back a fixed distance (and height) from the domino. The fixed height gives it a fixed impulse when you turn off the electromagnet and let the pendulum swing. Secondly, a domino on a sticky surface will rotate about (close to) the leading corner rather than the centre of mass, so it has a much greater moment of inertia and so takes longer to rotationally accelerate.

Try audio recording the fall of the domino's. But the visual spectrum on computer and you will be able to analyze the wave form to get the Beats Per Minute on a pre set amount of domino's per foot. That's how us DJ'S get the speed of a song, but we follow the bass line because it's constant.

How much energy was stored in all those dominos? I really can't estimate that, but it should be calculateable!

"there's a lot more greek letters in the math now"

I really enjoyed the educational bit at the end with the high speed camera. Nice job.

For your experimental setup, you could use a spring or a pendulum to set it off with a reproducible force. Using a computerized motor would work too, but it feels less like old-school physics experiments if it doesn't have a spring or pendulum! Also I have a theory as to why the slippage goes faster; I'm thinking in the limit where you have a frictionless surface and only rotation. Essentially your lever arm is shorter so you'll have less resistance to turning for a given input force. It'll have a higher rotational velocity and hit the next domino faster.

So it's fair to say that we should expect at least one more video on the physics of dominoes.

You can get a consistent trigger by setting up a simple pendulum that you always release from the same point. To assess the speed of a chain tipping about the bottom leading edge, make a jig that constrains the dominoes for sliding backwards. Please check the variations of the different types of dominoes too. What is the statistical variation in mass, geometry, friction coefficient? Thanks for a great channel!

Just came here from an American Physical Society article link on domino friction research, even though I was here 4 years ago. Congratulations on the citation/credit from this important academically respected institution! Well deserved; you do some of the best science on RU-vid, and your enthusiasm for it is infectious.

For consistency, I would initiate the domino chain using a steel ball on a string (pendulum) held at a point of positive potential energy (does not have to be high, just consistent) with an electro magnet. By disconnecting power to the electromagnet, the ball will be released with the same kinetic energy each time (consistency of pendulum periods). Hit me up, lets make some stuff !!!

A domino that slips rotates about its center of gravity as opposed to rotating about its edge. The moment of inertia about the center of gravity is smaller than that about its edge (see parallel axis theorem). Therefore a slipping domino will have a faster angular velocity than a pivoting domino. However, a slipping domino's reach is half that of a pivoting domino. As a result, the maximum reach for a slipping domino (approximately half of its height), would require 90 degrees of rotation, compared to 30 degrees for a pivoting domino. Since the distance function is sinusoidal (reducing horizontal velocity of contact edge as the angle increases), we can expect that pivoting dominos will perform better relative to slipping dominos with larger distances between dominos. We can see that the stack of fallen dominoes reinforces the falling domino and can assume that potential energy is not lost in a slipping domino compared to a pivoting domino. Mass shouldn't effect speed in a vacuum. Hypothesis: -slipping domino will be faster than a pivoting domino when spaced close together -pivoting domino will be faster than a slipping domino when spaced far apart -mass will have a negligible effect on velocity once the falling dominos have reached steady state

Destin, thank you for the video...made me flex my brain again. Bud...I would start by isolating variables. Construct a setup where the dominos are fixed at the leading edge (a hinge if you will) That way you'll have isolated to sliding factor. Make enough of them to achieve a steady rate of fall. You should be able to increase/decrease the mass of each individual domino to observe different response of the system. Comparing the results of the constrained system with the a free system should give you an understanding of what effects what. Looking forward to it!! Alex

The reason why slipping is faster (Physicist here) I'm going to try to articulate this as best I can. First, a falling structure's center of mass accelerates at g, this means the upper part of the structure will accelerate faster than g and the lower part will accelerate slower than g. Second, we don't care how long it takes for the domino to hit the rest floor, we care how long it takes for the domino to hit the next domino. So, a horizontal motion is more important than a vertical motion. So the slipping will cause the vertical motion to slow down, but the horizontal motion to speed up because the axis of rotation moves closer to the center of mass. Because the experiment is done in quantity, you don't need to understand the single domino, because each single domino will be slightly different. You should try to statistically understand the group of dominoes. So you can approximate and average the point of rotation which will be somewhere between the center of mass and the bottom tip. The more friction, the closer the rotation will be to the ground. When dominoes reach a steady state, they will have an initial angular momentum because of the initial impact and follow the following force diagram: docs.google.com/drawings/d/e/2PACX-1vSIyIdoI7PuXH7tXx_6yJKgbQ7FuJSe1RwWdZPci9bQL4IA423uNoSjjOQrPYzJJclWnfd-I_y_VcBI/pub?w=960&h=720

* laughs in Domino Day *

Use a stepper motor with a linear actuator. You'll get precise motion characteristics top start your tip. Also, you might consider measuring the frictional constants of your surfaces so you can evaluate that variable.

When it slips back the domino is rotating somewhere in the middle of the domino instead of at the base. That will cause it to rotate/topple faster since the more mass is closer to the point of rotation, like figure skaters spinning faster when tucking in their limbs. So, less friction causes the far end of the domino is brought closer to the point of the rotation resulting in faster spin of the domino creating a faster topple rate. That is my guess. Can't wait to see the results of your next test. Awesome channel

This brings me back to my advanced dynamic systems course in college. I knew I kept that textbook for a good reason! I'm thinking the variables you'd want to consider would include: -Friction of the domino on the surface -Friction between dominoes when they hit -Mass of the domino -Spacing (which really determines where the domino gets hit with a lateral force, which would determine the moment applied, which would determine how fast it rotates, which would determine the momentum going into the next domino) -Where the first domino gets hit -How much force the first domino gets hit with (probably not as important once you get to a steady state, but would it affect the steady state you get to?) Looking forward to all the Greek letters!

(3 ideas) Here’s the ideas for pushing them: 1: Use a solenoid, with a constant voltage from a power supply (so it’s exactly the same), to trigger the falling Mount the solenoid to the surface an mark a distance from it so the hit is at the same velocity each time 2: Now a solenoid may be too fast, so you could try some sort of small pneumatic piston Maybe even a lego technic one With a set pressure to go in each time Set it up the same as the solenoid 3: Again even that maybe too fast Or difficult Another way is to put a little paddle on a DC motor and put a constant voltage into it to push it I say this because it’d be the slowest way And if you want it even slower, you could put a gear train on it (Mounted the same as the first two; at a constant distance from the first domino to take that out of the equation) And all this takes out the human error Hope this helps!!!

Newton's cradle; try to keep the potential energy of the first ball equal, maybe set an electric magnet on a rod and let and turn it on to hang the first ball and off to release the ball. And try to keep the cradle just high enough to touch the dominos and not annihilate the whole setup

Can you use a stepper motor to trigger for consistency?

LOVED this video. Please do it again with a new set up.

I contributed in choosing that thumbnail 👊🏻

250,000? Just today they're doing 250,000? Us Dutchies did Domino Day back in the day. In we got over 4 million domino's to topple. 4 *million* .

Hi Julien, fascinating (I'm a physicist too, as well as a fan of Hevesh#5). Lili does know something to get a reproducible start of the toppling. In some of her videos she has a little motor, rotating a vertical axis on which a small lever of wood is mounted. That topples the first domino in a reproducible manner. Would love to see some more results of this investigation, as well as a comparison with the sonimods, a Lili invention, where the dominoes topple backwards while still giving a forward domino effect. Thanks for this video, in which two of my favorite youtubers combine their presentation and skills. Really cool!

Great video! I learned that the speed in which the dominos slip depends on the friction of the dominos and the surface.

You can use a mini electric motor for a more consistent push, and you can also bind a small plank to it so it could push multiple rows. And for the acceleration problem you can lay down a longer path of dominoes then just focus the end of your trail with the high speed camera. As for how you could tackle Tribology, usually physical systems behave in a characteristic fashion, so it might be possible to still be able to simplify the explanation of the dominant forces in play and explain to us how it all works together. Who knows, you might figure out something that domino builders will have to take into account in the future for things like timing very long trails. Because there might actually be a way to make a 1 in [number] correction to the difference in dominoes in use. (ex. having two long branches where one uses 500 more acrylic dominoes that need to come together at the end) As a side note i wonder how the max speed behaves in different friction surfaces, and what exactly happens if you move from one surface to another

Mind blown, they slip not just pivot.

Does the vertical height that you tap the first domino affect the acceleration of the first 20 dominoes?

Best way to start would be using another domino in a preceding cascade leading up to the starting point. As long as the "starter" sequence of dominos shared the same surface/friction/color/spacing/count, you could change any variables after that point. Measure start time from first contact with the non-starter sequence. Love your channel!

Trigger it with a DVD player tray That’s what I did for a school project when we needed to push a toast from a table and tried to find what causes it to fall on the butter side

When the domino goes from rotating at a point near it's Centre of Gravity (CoG) to a pin joint at the base, the lever arm becomes the distance from the pin joint to the centre of force (the preceding domino's inertia), so you would get a higher velocity at the top of the domino as the distance over which the force is acting has almost doubled. I assume that the heavier domino's would have a greater inertia and therefore a higher velocity? You'd have to devise a method of calculating frictional forces (between dominoes, dominoes and floor etc) to work out whether you'd actually go faster with lighter or heavier dominoes (only way colour could have different speeds in eu is different weights between colours).

I can't wait to see the next video- also I suggest making a small contraption to push the dominoes at a specific point every time

i miss domino day one the TV

Let's all appreciate that Domino Day will stay as the Nr.1 in Dominos With over 4'000'000 Domino Stones it holds the World Record in the Netherlands

There are two main variables when trying to initiate the dominos, and you will need to keep both consistent in order to trigger properly: The velocity, and more importantly, the location where the force makes contact with the domino. If you had dominos with different densities and you strike them at the same location, you can expect different results. A pendulum striking the top corner can work on same size dominos. You can also use a pneumatic air tool (regulated) to blow a shot of compressed air directed at the top corner of the domino. You can create a domino-sized magnet as the lead domino, and drop another bar magnet from a string a consistent distance away from the top half of the domino magnet to create a consistent repelling force. Similar to the above, you could use an electromagnet on a push switch to initiate the fall on the first domino.

Hi Destin. I am Cornel (a mom and engineer) from South Africa and love your videos. I was wondering if the poke the domino stick would not work better if you use a pendulum with a set starting point or a piston type starter for a more consistent movement. Thank you that we can get smarter everyday

To keep the domino starts consistent use a pendulum to trigger it. Let it swing from the same spot every time (maybe use a latch to release it) and set up the dominoes in the same position relative to pendulum every time. This was just the first thing that came to mind when thinking of a solution 👍🏻love your vids btw :·)

The more mass, the more potential energy when standing, the more kinetic energy when falling. But, on the other hand. The more mass, the more force it takes to accelerate. I can't decide which of these factors is more important, or if they equal out.

My suggestion on your setup would be to have a runup line of dominos that remain the same so that your inconsistency in the way you trigger the line has a chance to be removed by the time your test dominos are triggered. You could further remove that inconsistency by making your trigger at the beginning of that runup be more mechanical like a falling weight or solenoid or something like that. BTW Destin, I love your channel. Your excitement for the act of discovery is infectious. Thanks.

Very cool as usual. Love looking up the scriptures associated with each video.

I like how they went from really serious before the event, to super happy right after. It shows how much passion they have for what they do, and that's really dope.

what are the requirements for the records? I know here in the Netherlands we have a record of around 4.5M I guess we just have way to much time on our hands... For the suggestions I would say put a big row of dominoes before the ones you are measuring and let it either end abruptly (if this helps with calculations) or put more dominoes at the end so the last one you measure falls on (and has friction with, or resistance from) the next dominoes. A long start might eliminate the factor of the topple speed of the first domino. But to topple the first one you could use a mounted 'spring device' just like a (clicking) ballpoint pen. But it would be better to use a motor with an 'arm' turning very slowly. Either get the arm into the same position each time before turning it on, or let it turn so slow you could move the motor in (and come to a halt again) before it topples the first one. p.s. Some fun suggestions that might not be very accurate. 1) Let the line start in front of the camera, let it loop around and end behind the dominoes that have already fallen. 2) Test friction between dominoes by placing them together as close as possible. 3) What happens if you tape dominoes together in pairs? And could you simulate the "double domino effect" with it? or would that make it a "double double-domino effect"? ha-ha... 4) Dominoes under water!? If they don't float of course. I can go on for ages but I should better stop, before no one in their right mind will ever read all of it!

I was about to comment on the inconsistent starting mechanism when you brought it up yourself. Great video Destin.

bought a casper this summer. used your code.

i believe if you have a long enough chain of dominos the initial conditions shouldnt matter. you can use the data from time when things are in dynamic equillibrium. when you see constant velocity. than next step could be to see the acceleration for each material and boundry condition by using the pendulum method or a ball and ramp method.

Can't you use like a little swing as a trigger? Putt a small stop on the swing so you cant pull it back all the way. Then every time you do start the test you pull it back to the stop. This will give you the same distance every time which results in the same speed for the swing. Making the swing hit the domino the same way every time, just keep in mind the first domino in every test need to be the same exact distance from the swing.

Really enjoyed this, particularly the analysis at the end. I want to see the rebuilt rig! Solenoid or servo to trigger the fall? Servo might allow you to control the actuation speed better.

Always nice when someone does the experiment and not just the theory and maths. Could use a pendulum to knock first one down. A curve seems to slow it so it might regulate the motion before the camera straight section.

*Trigger* : I think a *solenoid* would be best. You can use the signal, used to trigger the solenoid, to trigger the camera. That way you can *compare Time* more easily.