You are so awesome I'm 58 and want to teach my Church youth about how God put the world together and every video you provide brilliantly shows this in ways that can be replicated by anyone with few resources. I applied you Sir!!! Standing Ovation from this guy :)
Brilliant man, to be able to come up with all these exhibitions to demonstrate what is normally unobserved by many people. This gentle man should have a science museum named after him, as as yet I have not known anyone who is as dedicated to make children and others aware of all the beautiful issues in our universe. Sir, my congratulations. This equipment also shows the effect and the difference between static and dynamic friction.
I know this was meant to just highlight some fun interactions, but this "angle of repose" is actually something I deal with DAILY at my job. Long story short, I work with an aggregate product that includes particles the size of dust all the way up to chunks a couple inches thick. If left too long, the product "sets up", meaning it actually locks together. When that happens a pile of it can actually create an angle of repose that's 90 degrees, literally a cliff. That can be a very bad thing. We have air cannon vibrators, air spears, and dynamic dumping points. Unfortunately some times that isn't even enough and we have to break out the explosives, all just to get some powdery gravel moving. I've spent the past few months trying to come up with novel new way to conquer these problems, but so far have had no luck whatsoever. I've tried to work with digital versions of the sand toy you showed, but unfortunately they don't allow for simulation of a product like mine. Any suggestions would be much appreciated. If I could find new ways of dealing with my product, I could save my company millions of dollars.
Why it sounds like you have a really cool job! This type of job never entered my mind. Or the problem your facing. I hope some brilliant person out there can help you find a solution!
I know your comment is over a year old but have you experimented with fluidisation to help solve your problem? ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-zjgURBIqJ6s.html
I dig your sand experiment. I had an idea, what if you were to make your holes through the bar intersected by an oversized hole that is perpendicular to the plastic faces, then you could insert dowels into the holes and drill holes through them, leaving a little nub sticking out through the face of the plastic that you could turn, creating something like a ball valve? That way you could open and close the holes without taking the thing apart.
You should put spring loaded pegs going out perpendicular that can be locked open when you want to open the holes. or a stopcock valve design that can be turned to open them.
Hello, Mr. Yeany. I was directed to your video while searching for a better understanding of what the engineering term 'Angle of Repose' means. At a young age, I discovered I had issues with understanding even basic algebra. I'm not proud of that, but I wish now that I'd had a teacher or tutor available who would've spent more time helping me, rather than immediately placing me in the slow math class each year. I managed to graduate university with the most basic math credits required, furthermore, I never enrolled in chemistry or physics or took a single course that required any mechanical aptitude. It was Wallace Stegner's "Angle Of Repose", of all things, that led me to you. I wanted to understand the meaning of the title. I'm a logophile and epistemic enthusiast. If science were a tree, I've only studied the limbs involving biology, anthropology, and medicine. I've never had the confidence to approach the many branches of chemistry and physics and quantum mechanics and thermodynamics and so on. All of those have remained in the dark, that part of my brain stubbornly quiet. Physics is a mystery to me; truly, all of the fields I just mentioned are on a sort of mystical level in my mind and I'm both fascinated and daunted. In any case, this is all to say that I enjoyed this video and I appreciate your straightforward style. Do you have any "beginner's physics for the mathematically stunted" videos available? I'd be keen on viewing them. I'd love for the veil in my brain to fall away, to have a light shine on at least some of what has always seemed off limits and unknowable. It's my belief that in learning some basic physics and the like, I'd better understand how many other things work. If that makes sense... Light bulb moments are divine. If you've made it this far, thank you.
Dear crowded crow, I made it the whole way. the only videos that I have are the ones that I have posted on youtube If you are looking for courses without the serious math requirements I might suggest Paul Hewett's conceptual physics. He has textbooks and videos available. Seems like there are others on youtube that are quite good. I'll take a look and see what I might suggest
You could improve the wooden "toy" by make holes from one side throw where the vertical holes are, and put sticks in it. If you pull one stick out a bit (not the whole stick, because sand gets out), than the sand can run down, if you push the stick back, sand cant run down in that hole. So you dont need to take the toy apart for switching holes. :) Or you can make a wide hole through the whole toy where there is a vertical hole and make a wide stick with a hole in the middle and put that through the whole toy. If it has little sticks attached the two hanging out part, than it can not fall out from the toy but you still can push or pull the stick and the sand only runs when the holes get together inside the toy. Hope you can understand :) I love your videos and ideas. I wish we could have teachers here in Hungary like you :)
You can use screws instead of sticks. Its easier to pull out (screw out) without the risk it falls out from the toy. This type: www.clasohlson.com/medias/sys_master/8872506589214.jpg
Hi Dani, I'm glad you like them and it's great to hear from someone from Hungary. I've tried a few other ideas on how to make it easier to change the holes, but they either got stuck or would leak the sand out. I have one more that I am making but it is in larger plastic jars with the lids. These make it a lot easier to change around than the wood frame
stickmandaninacan Indeed. Waiting for some surprising revelation, or strange effect, or genetal law of physics, or interesting insight, or whatever, and... nothing. Just sand that does what it always does: piling up. Hm. I feel a little bit duped.
The speed of falling particles (or falling height) changes the angle. Not just speed, the diameter (or length) of the base and roughness of base plate also changes the angle of the heap. For more info please check: Miura, K., Maeda, K., and Toki, S., 1997, “Method of Measurement for the Angle of Repose of Sands”.
Next, demonstrate rolling separation in an uneven mixed material with different densities and grits... Use coloured material to demonstrate the separation!
Hello Mr Yeany, as always you’re sharing some great science ideas. We actually had some sand "Flip Over Toys' here in India a kind of key rings that when turned has some msg word like 'Hi' or 'I Love You'. Pretty interesting was in those days when simple toys were actually based on simple mechanics of nature handmade by local craftsmen and your video reminds that. Thanks for the Homemade Science.
Hello Jigyasa Foundation, good to hear you find some of my videos interesting. It has always been my goal to try and get students interested in viewing science with real objects rather than reading about them or computer simulations. I'm not sure I understand about your toys that flip over but I like the idea. Thanks for the note, it's nice to hear from friends in India. Bruce
+Bruce Yeany (Yeany Science) Sir, the toy used to be just a small round transparent box where the sand just falls (when you turn it over) through some Alphabet Stencil type cut (rather than a hole) that finally make the msg clear like Hi or Hello after some sand had fallen through the stencil and the rest just settles around beautifully . Anyway Sir, we’ve got an idea to make one and show it you from our Jigyasa workshop (where we usually make mechanical puzzles). We’ll share a video soon for you & the students. Warm Regards, Jigyasa
i would like more in depth explanations with a theoretical background (like a formula for the angle of repose) when i saw your stringshooter i also wondered what dictates the speed of the propagating waves when touching it very nice videos nontheless :)
Sorry, these pieces were attempts to get kids interested, since I teach middle school we don't get into either of the concepts in the depth that you desire, however, you are right I should have given more here
Great visualizations -- thanks for the video. I just learned of the angle of repose from the "After the Hunt: More Secrets of Egypt" episode of Travel Channel's "Expedition Unknown", where Josh Gates talks about how the Egyptians building the later pyramids (e.g. the Great Pyramid of Giza) to a compatible angle of repose is why they've lasted so long intact, while earlier pyramids whose angles were too steep did not. (Josh was trying to convince his ever-superstitious cameraman Evan that the pyramids have lasted so long because of good engineering, not due to being built by aliens!)
Bruce Yeany guess it has something to Do with the new recommendations algorithm or so. I see your videos showing as recommendedsince a few days and all I have seen are very good. Keep up the good work sir.
this guy/channel is friggin so cool....I wish I had a teacher like this just one year in jr high or high school...for some reason the way he does his explaining actually gets me thinking and asking questions instead of numb brain bored to death, not caring and falling asleep. great Chan man! keep up the AWESOME work! WAY WAY way better than crazy Russian thief hacker vids
I wonder if this is the angle of the pyramids ? I do know they wanted to build them at a much steeper angle then they were able to do so . If my memory is correct it was 72 degrees .
Yes, I actually misunderstood him when he talked about blocking the holes and thought he was saying he had little wood blocks to stick in from the side to open or close the holes, so I was quite surprised when he started taking the whole thing apart.
I wonder if the tape/hole system could be replaced with some sort of thumb-screws that allow you to open/close the holes without taking the whole deal apart. (Or perhaps a set of masks with holes that slides into a groove?) That would speed demonstrations up.
Rather than unscrewing the whole panel, you could use screws as blocks for the holes. (Similar to a pin valve) that gives the benefit of adding a 3D visual confirmation of which holes are open or not... Though I do find it interesting the relation between the curve of probability and the angle of repose...
you're right it is a pain, I was thinking of trying small pegs at each hole that have holes in them, turn them to either let the sand through or to block it.
I was thinking you'd be better off using a rubber door seal between the perspex and frame, just use a good few butterfly clips or clamps to hold it together, much easier to open. Or if you can put a smaller piece of wood through the central piece then you could drill holes in a fashion that moving the smaller piece would open and close certain holes so you'd never have to to open it up.
Bruce Yeany I imagine if you placed the holes between your screws but also made holes going through one side that intersect with the holes for the sand, you could just place dowels in the holes you wish to block, and remove them from the ones you want the sand to go through. No opening needed!
Thanks Bruce, I love this video. I'm thinking about recreating some of your demonstration devices for a kids' science club, and experimenting with different materials (eg flour, salt, cumin seeds etc) to see whether we observe any variation in thee angle of repose. I'm guessing that more angular particles should exhibit more friction, so have a steeper stable angle, and that lighter materials should have greater friction to weight ratio which might also make a difference. Have you tried aby different materials? if you could suggest any common ones that exhibit noticeable differences in the angles I'd be grateful.
you should make a piece of wood with holes that can slide in the middle of the box so all you have to do is move the small stick of wood back and forth to change the number of holes
interesting presentation. does viscosity change the results, (ie, coat the particles with a lubricant) or temperature, barometric pressure, size of particles, latitude of the physical location where the experiment was conducted, ( i do like your work, never stop being you.)
Hi Molly, some factor will affect it more than others, type of particle, size, density, powder, if it is damp or not all change it, the temperature or barometric pressure probably not so much
What exactly is it that determines the angle of repose? Is it a function of G? Would it be steeper on a lower G world like Mars and higher on a higher G planet?
An example of real life disaster related to this is Aberfan in Wales I about 1966, when a coal slag heap from the mines collapsed onto the village school.
your experiment seams like it wants to create an Equialateral Triangle.sand seams like their could be variables on grains falling left of right. rocks be uniquely shaped. i wonder if steel BB's would produce an Acute Angle or something more flat. i enjoy your channel thanks
I guess whether the sand goes left or right might be an example of chaos theory. The angles formed are also going to be dependent on the amount of friction between the particles, the more friction the higher you could stack it and the steeper the angle. Without enough friction between them, I would think the BBs wouldn't pretty much flatten out. I haven't played around with any other materials other than the sand. thanks.
Yes, speed (falling height) changes the angle. Not just speed, the diameter (or length) of the base and roughness of base plate also changes the angle of the heap. For more info please check: Miura, K., Maeda, K., and Toki, S., 1997, “Method of Measurement for the Angle of Repose of Sands”.
Damian Rozycki I looked into it, the Giza Pyramid is at 51 degrees from bottom to top. I bet if it started to crumble, though, the heap would be at 30 degrees.
yes, the size of the particles density, and shape of the particles all make a difference, if you do a search for repose angles, you can find a list of the angle for several types of materials
Hi realcygnus, the guitar music is taken from a file on my Mac computer, it is an apple file that can be imported into videos. They don't give a listing who is actually playing it
This video has a lot of focus on the concept of critical angle and the observation of such, but you almost only describe why materials have a critical angle in the description and don't go into depth about that. That's a shame. Also as previous commenters said, the undoing of those screws is quite a hassle. What you could do is make the divider have a hollow section through which you can move a slider. This slider could have holes at specific points to coincide with holes on the divider, making it so that you can choose the amount of holes by moving the slider.
Why not just put screws in the middle piece where the holes are and then you just have to back out the screws to open the hole instead of taking the whole thing apart.
HI John, this is my first design for this, yes, it can be improved but for now it is fortunate that I have several students that enjoy using the electric screwdriver and changing it around
