What an incredible demonstration the sticks on the side of the board are! That turned this from a kids experiment into something that got my brazen adult mind racing. The sticks act like a floating o ring in a piston. To even consider that the explanation for such a classic experiment is wrong is the most impressive part.
Same thing happened here. This demonstration is super impressive even to adults. Completely mindblowing to imagine little pieces of wood on the sides not even on top of the board can make such a difference.
LOL, the boards don't hurt but a few years ago I was doing this and my aim was off, hit the desk instead which didn't break, my hand hurt for weeks afterwards
Thank you for doing this! The explanation of the force on the newspaper has bothered me since I was in middle school! The explanation of sealing the air from getting under the board makes so much more sense!
Nice video, I was totally along with you until the jump to using board pieces to seal the sides. Seeing that jump in logic to prove it really is just sealing air from getting underneath to make this work was so awesome!
You came up with really good variations to zero in on the most accurate explanation--really shows just how interesting scientific investigations can be!
Thank you so much for making these videos Bruce, I'm a huge fan. I love the way you methodically work through the holes in the theory. The final demonstration was fantastic and unexpected.
That makes me envision a terrific bar-bet (albeit a messy one)...4 unequal pieces of wood, you can only touch one piece at a time and only use one hand. The object is to break the board without any additional tools. Just found this channel through Nighthawk&Light and absolutely love it. I wish more teachers were like you kind Sir! Also, I’ve been trying to guess your State, and think it is either upstate NY, or MA.
I wasn't sure what was gonna happen with the side boards! it only had to come up such a tiny amount and air would be able to get in! very impressive demonstration!
Thank you, Sir. This is really it! It intuitively made sense to me, but you showed an ingenious way to prove it. Kudos! (And thanks for the link to this video.)
Before I get to the explanation, I think it's about creating slight vaccuums. The whole paper basically works as a loose suction cup, and because it's over a wide area, basically there's not a lot of room for air to come in underneath. With a wide board, getting it to move would require a lot more air for it to have the space to move in the direction it wants to (flipping upward as the other end is smashed down). A smaller boar would require less air/space in order to do that, so it much more quickly reaches the point where it has enough air to move around and thus tug the paper along with it in the process. Let's see if I'm even half right!
But if you push down on the end of the board slowly, it doesn't require 700+ pounds of force to tilt it. So it seems like there must be some additional explanation related to how fast the air pressure can equalize. E.g. at the instant the board starts to lift up (creating the vacuum underneath), there's only a very tiny opening that higher-pressure air can flow through. The board just can't absorb the full force of that blow in such a short amount of time, and the pressure can't equalize in time to let it pivot more freely to dissipate the force that way... Whereas if you tilt the board by applying force more slowly, there's plenty of time for air to rush in and fill the vacuum even with that very tiny initial opening.
Bruce! Great experiment and the explanation is much better then it was before. But I think that the viscosity of the air is playing a huge role in this experiment. Your side blocks do not allow the air to flow around the board freely, so you need to push all air up while hitting another side. This causes a huge resistance force. Happy Christmas!!!
get a 1 meter by 1 meter and 1cm thick mdf platte and drop it as leveled with the floor you can, can you explain the air bed or wtv happens that makes it fall softly at the last moment and make almost no noise?
I want to expand on this a little more. While it's true ambient air pressure is acting on the top surface and preventing air from getting under the board ultimately breaks it, I don't think this is the best way of explaining it. Generally speaking for most things ambient pressure is acting equally from all sides cancelling itself out. Likewise between most things there's always a tiny air gap or air pockets unless we're specifically speaking about precision ground gauge blocks sticking together. On that note, removing the air pockets with water and the added effect of surface tension might also break the board. Moreover making airtight seals usually requires rubber seals, generally speaking. So assuming there's a tiny air pocket below the board in all these cases as soon as the board moves at all the volume expands and the pressure has to drop. Because we're talking about such a tiny air gap the boards doesn't have to move very much for the pressure to drop a lot. In other words we form a vacuum (air pocket with below ambient pressure, not a perfect vacuum) below the board which you can clearly see at 04:15 where it sucks the plastic wrap into the vacuum. The way I would explain it is that there isn't a perfect seal nor is there a perfect vacuum - but in this fast phenomenon the air doesn't have enough time to leak and fill the vacuum until the board reaches the breaking point. The pressure difference acting upon the board is a more useful concept in physics. Technically there's an element of air resistance in the top side of the board too but that probably only raises the air pressure on that side just slightly above the ambient as the air doesn't have time to move.
thanks for your comments Mikko. It's been interesting doing this experiment over the years. A few other factors that I could mentioned, the inertia of the board itself or the air resistance, I was trying to keep it simple. To expend on the points you've mentioned, the quality of the wood and the table surface is a BIG factor. The boards need to be straight, any bows in the wood will allow more air under it and ruin the experiment.. The table that I am using is a science lab table but is not completely smooth allowing micro air pockets underneath it. My favorite surface has been a Formica table top that is extremely smooth, when I lay a 2nd board with a formica surface on it, it reduces those air pockets considerable and is much harder to move away from the surface quickly. Also found it was not a good to try this on a lightweight table as it will tilt upwards slightly on impact, much more so when paper is on top than without. I did mention that the 800 pounds of force is only with a good seal in passing should also have made this clearer. In trying to keep this simple, I didn't want to add water to the table, since it would then add the idea of adhesion to the explanation. However, hopefully I will come back to this again, with a few more variations and try to clarify the points a bit better.
Thanks for the insightful reply. I agree that for this experiment estimating the air resistance and inertia to be minuscule/negligible is correct and choosing to omit assessing them for the sake of simplicity is a valid choice. I just found this set of experiments thought provoking and certainly many different variations could come out of this. I'd be interesting to first measure the amount of force required to break the boards in the cinder block scenario 01:15 to establish a baseline and to 'break the board by with gravity'. (sure, it's a lever arm but that could be accounted for) The current experiment is kind of 'break the board with air pressure'. I hypothesize if you were to attach the board to a regular hinged door (that's seemingly free to move) you could break the board with air resistance by 'pushing against a column of air'. Really the variations and possibilities are endless. Looking forwards to a follow up, merry Christmas and a happy 2020, Bruce!
My chemistry teacher did this for us a few times. He used rulers though, so one time it came out and nearly got me because my seat was right in front of his table. I never really thought about it enough to realize the paper was just to keep the vacuum under the wood
Could you please elaborate on why the flimsiness of the newspaper matters? You mention that it is not a rigid body, but how does the rigidness of the body influence this phenomenon?
for the boards to break there has to be a imbalance of pressure on it, my theory is that the narrow boards allow air to get under them quicker / easier as they are hit. You can feel a big difference as you push down gently on a thin board versus wider one
Wow! Absolutely remarkable! When I was a boy my sister and I were diving off a large rock into the creek. Dad had us diving, hands at sides, head first through innertubes. Our older cousin who owned the campground, told us about another family camping and children diving off a big rock same as us. Their dad opened up a newspaper, laying it flat on the water. One child dove first, hands at sides, headfirst but, the newspaper was like concrete on the waters surface. The child, unable to break through the paper, immediately broke his neck.
Seems like surface tension, I bet it would work if you wet the bottom of the board as well. May even work upside down, if the surface tension was sufficient.
thanks John, interesting idea. The water would be added adhesion to it, that might do the trick. I also want to try it sideways with the small boards taped to a wall and the large one resting in-between
It would be nice to have a reliable machine used to apply a repeatable force to break the board to eliminate variables... a bungee cord maybe? Or a weight on a pendulum?
thanks Big Al, as I was making this, I was wondering how I could go large with a full size board I will need to come up with something other than hitting it with my hand
I like that you broke down the experiment to demonstrate what’s really going on. I feel like I was making my hypothesis along with you.
What an incredible demonstration the sticks on the side of the board are! That turned this from a kids experiment into something that got my brazen adult mind racing. The sticks act like a floating o ring in a piston. To even consider that the explanation for such a classic experiment is wrong is the most impressive part.
Same thing happened here. This demonstration is super impressive even to adults. Completely mindblowing to imagine little pieces of wood on the sides not even on top of the board can make such a difference.
You should teach teachers on how to teach...
Thank you, merry Christmas and a happy 2020, Bruce.
thank you Kabral
Bruce returns to school the next morning with his left hand bruised and in a cast!!!
Greatest teacher ever!!!
LOL, the boards don't hurt but a few years ago I was doing this and my aim was off, hit the desk instead which didn't break, my hand hurt for weeks afterwards
@@YeanyScience that's what I was afraid of while watching this video
I am almost 40 and I am still learning. Thank you!
I'm almost 50 and state the same. Life is a journey of endless learning.
People like Bruce are the true champions to explain the world around us.
Thank you for doing this! The explanation of the force on the newspaper has bothered me since I was in middle school! The explanation of sealing the air from getting under the board makes so much more sense!
Justin Poirier the one that always stumped me was 'lift' on an airfoil
You must have been one of the favorite teachers in school.
I have a friend who didn’t like him in school and I am rethinking that friendship.
He was.
@@profudg3612 That may be who gave the thumb-down for the video.
He was definitely one of the favorites! I remember useful things from his class, I can’t relate that to many other teachers.
Good processing on this one! :) The demonstration with wood strips was the "ah ha" / confirmation moment for me. Thanks for the video!
Nice video, I was totally along with you until the jump to using board pieces to seal the sides. Seeing that jump in logic to prove it really is just sealing air from getting underneath to make this work was so awesome!
You came up with really good variations to zero in on the most accurate explanation--really shows just how interesting scientific investigations can be!
This is my new favorite video you have posted! A surprising, but convincingly demonstrated explanation of the phenomenon. Thanks!
I love your chuckle. I show your videos to my children. Third generation taught by you. Love it!
Hi Jess, nice to hear from you. Hopefully you remember a couple of these demonstrations from 8th grade.
чудова демонстрація - дякую!
Thank you so much for making these videos Bruce, I'm a huge fan. I love the way you methodically work through the holes in the theory. The final demonstration was fantastic and unexpected.
The investigation and thought process was wonderful to see. Great video, as always
Great demonstration of scientific method Bruce. Thanks.
That makes me envision a terrific bar-bet (albeit a messy one)...4 unequal pieces of wood, you can only touch one piece at a time and only use one hand. The object is to break the board without any additional tools. Just found this channel through Nighthawk&Light and absolutely love it. I wish more teachers were like you kind Sir! Also, I’ve been trying to guess your State, and think it is either upstate NY, or MA.
I wasn't sure what was gonna happen with the side boards! it only had to come up such a tiny amount and air would be able to get in! very impressive demonstration!
Aww! I truly appreciate this video. It reminds me of an episode of "Mr. Wizard" that aired when I was a child. Oh nostalgia!
I couldn't help but let out an exclamation when you broke it with the small strips of wood! Incredible stuff
This was explained and demonstrated so well! Thanks for this video showing the physics behind the experiment.
Thank you, Sir. This is really it! It intuitively made sense to me, but you showed an ingenious way to prove it. Kudos! (And thanks for the link to this video.)
6:20 That’s the greatest idea. And the result is awesome too.
Holy Crap!! this is amazing! ya think u know science until u see this...thank u for this video. Happy holidays Bruce!
Brilliant as always Bruce. Thank you for your video
Very interesting that those small strips of wood would work. Great video
That's fantastic, Bruce 👍
Wow! Great video and great investigation/experimentation.
Great video! Very good presentation!
That final experiment blew my mind.
This is a brilliant update!
Love your work, Mr. Yeany. Keep it up :)
Hey Bruce, nice to see you! Greetings from Europe.
Thanks Christian, nice to hear from Europe
You are awesome, Bruce!!!!
Before I get to the explanation, I think it's about creating slight vaccuums. The whole paper basically works as a loose suction cup, and because it's over a wide area, basically there's not a lot of room for air to come in underneath.
With a wide board, getting it to move would require a lot more air for it to have the space to move in the direction it wants to (flipping upward as the other end is smashed down). A smaller boar would require less air/space in order to do that, so it much more quickly reaches the point where it has enough air to move around and thus tug the paper along with it in the process.
Let's see if I'm even half right!
Awesome! I wonder what the result would be if you drill holes in that board.
But if you push down on the end of the board slowly, it doesn't require 700+ pounds of force to tilt it. So it seems like there must be some additional explanation related to how fast the air pressure can equalize. E.g. at the instant the board starts to lift up (creating the vacuum underneath), there's only a very tiny opening that higher-pressure air can flow through. The board just can't absorb the full force of that blow in such a short amount of time, and the pressure can't equalize in time to let it pivot more freely to dissipate the force that way...
Whereas if you tilt the board by applying force more slowly, there's plenty of time for air to rush in and fill the vacuum even with that very tiny initial opening.
Bruce! Great experiment and the explanation is much better then it was before. But I think that the viscosity of the air is playing a huge role in this experiment. Your side blocks do not allow the air to flow around the board freely, so you need to push all air up while hitting another side. This causes a huge resistance force. Happy Christmas!!!
thanks llya, there are probably other factors that also contribute such as inertia which I didn't mention. It's been a fun experiment
This was kind of my theory as well, i want to try it with water on the bottom surface, and nothing blocking the sides.
Amazing!! Nice experiment!
that is fascinating. By grace I need to show this to my nieces.
This Is STUNNING!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Happy Holidays Bruce!
Amazing! Kind regards from Austria👍
thanks, nice to hear from Austria
get a 1 meter by 1 meter and 1cm thick mdf platte and drop it as leveled with the floor you can, can you explain the air bed or wtv happens that makes it fall softly at the last moment and make almost no noise?
Great video Mr Bruce (Lee)
You are legend sir love your science.
I want to expand on this a little more. While it's true ambient air pressure is acting on the top surface and preventing air from getting under the board ultimately breaks it, I don't think this is the best way of explaining it.
Generally speaking for most things ambient pressure is acting equally from all sides cancelling itself out. Likewise between most things there's always a tiny air gap or air pockets unless we're specifically speaking about precision ground gauge blocks sticking together. On that note, removing the air pockets with water and the added effect of surface tension might also break the board. Moreover making airtight seals usually requires rubber seals, generally speaking.
So assuming there's a tiny air pocket below the board in all these cases as soon as the board moves at all the volume expands and the pressure has to drop. Because we're talking about such a tiny air gap the boards doesn't have to move very much for the pressure to drop a lot. In other words we form a vacuum (air pocket with below ambient pressure, not a perfect vacuum) below the board which you can clearly see at 04:15 where it sucks the plastic wrap into the vacuum.
The way I would explain it is that there isn't a perfect seal nor is there a perfect vacuum - but in this fast phenomenon the air doesn't have enough time to leak and fill the vacuum until the board reaches the breaking point. The pressure difference acting upon the board is a more useful concept in physics.
Technically there's an element of air resistance in the top side of the board too but that probably only raises the air pressure on that side just slightly above the ambient as the air doesn't have time to move.
thanks for your comments Mikko. It's been interesting doing this experiment over the years. A few other factors that I could mentioned, the inertia of the board itself or the air resistance, I was trying to keep it simple. To expend on the points you've mentioned, the quality of the wood and the table surface is a BIG factor. The boards need to be straight, any bows in the wood will allow more air under it and ruin the experiment.. The table that I am using is a science lab table but is not completely smooth allowing micro air pockets underneath it. My favorite surface has been a Formica table top that is extremely smooth, when I lay a 2nd board with a formica surface on it, it reduces those air pockets considerable and is much harder to move away from the surface quickly. Also found it was not a good to try this on a lightweight table as it will tilt upwards slightly on impact, much more so when paper is on top than without. I did mention that the 800 pounds of force is only with a good seal in passing should also have made this clearer. In trying to keep this simple, I didn't want to add water to the table, since it would then add the idea of adhesion to the explanation. However, hopefully I will come back to this again, with a few more variations and try to clarify the points a bit better.
Thanks for the insightful reply.
I agree that for this experiment estimating the air resistance and inertia to be minuscule/negligible is correct and choosing to omit assessing them for the sake of simplicity is a valid choice.
I just found this set of experiments thought provoking and certainly many different variations could come out of this.
I'd be interesting to first measure the amount of force required to break the boards in the cinder block scenario 01:15 to establish a baseline and to 'break the board by with gravity'.
(sure, it's a lever arm but that could be accounted for)
The current experiment is kind of 'break the board with air pressure'.
I hypothesize if you were to attach the board to a regular hinged door (that's seemingly free to move) you could break the board with air resistance by 'pushing against a column of air'. Really the variations and possibilities are endless.
Looking forwards to a follow up, merry Christmas and a happy 2020, Bruce!
My chemistry teacher did this for us a few times. He used rulers though, so one time it came out and nearly got me because my seat was right in front of his table.
I never really thought about it enough to realize the paper was just to keep the vacuum under the wood
Could you please elaborate on why the flimsiness of the newspaper matters? You mention that it is not a rigid body, but how does the rigidness of the body influence this phenomenon?
Absolute amazing!
Learned something new here!
This is so amazing!
Why doesn't it work with the narrower board?
for the boards to break there has to be a imbalance of pressure on it, my theory is that the narrow boards allow air to get under them quicker / easier as they are hit. You can feel a big difference as you push down gently on a thin board versus wider one
Very nice 👍👌
I wasn't convinced until the wood strips.
Wow! Absolutely remarkable!
When I was a boy my sister and I were diving off a large rock into the creek. Dad had us diving, hands at sides, head first through innertubes. Our older cousin who owned the campground, told us about another family camping and children diving off a big rock same as us. Their dad opened up a newspaper, laying it flat on the water. One child dove first, hands at sides, headfirst but, the newspaper was like concrete on the waters surface. The child, unable to break through the paper, immediately broke his neck.
Bruce Leeny dropping karate chops like a magician in this episode!
I've noticed something similar when lifting cardboard / plywood boards resting on eachother. The lower boards lift eachother upwards.
same thing, good observation
That was fantastic.
That's amazing 😯
Love this! But also triggered some PTSD from growing up with nuns who hit you with their hands and rulers...
Fantastic!!
marvelous!
Hey, can you Make a video about tensegritys.
Seems like surface tension, I bet it would work if you wet the bottom of the board as well. May even work upside down, if the surface tension was sufficient.
thanks John, interesting idea. The water would be added adhesion to it, that might do the trick. I also want to try it sideways with the small boards taped to a wall and the large one resting in-between
Try the 1" strip with the pieces of wood blocking the edge pls
I did, I had one left and it works, unfortunately I didn't have the camera set right
@@YeanyScience did it react the same as when you had the paper on it or did work better? It was surprising how well the wood at the edges worked.
world class teacher
great video, I learned a lot from it and it was really surprising.
I bet karate tricks use this knowledge :P
I wish I could give two thumbs up.
It would be nice to have a reliable machine used to apply a repeatable force to break the board to eliminate variables... a bungee cord maybe? Or a weight on a pendulum?
thanks Big Al, as I was making this, I was wondering how I could go large with a full size board I will need to come up with something other than hitting it with my hand
A bowling ball on a guided drop chute. That’s the ticket if you’re scaling up! You would have to take the class outside for that one though.
Sick!
1:00
What a swag!!😎😎
I think this video is just a flex of what he can do with wood
I wish you were my science teacher.
thats my next party trick sorted
I thought the common explanation was correct. Great video
I just been trying this out with dried lasagna sheets ✌🏽
Everyone on Reddit should come here after three scratches of the head.
Wow, great myth busting Bruce!
🤯
Obviously it's because the newspaper is secretly as heavy as a brick!
First ask a question. Come up with hypothesis. Prove hypothesis with multiple experiments. Fab.
Kung fu master
Note to students: _Don't mess with Mr. Yeany!!!_
5 stars
Savage
hi mr bauer who is reading this in the future