How Does The Ruler Trick Work?

hey everyone today i'm going to be showing you how the ruler trick works so i have a regular ruler here laying off the edge of my table you can see it's barely balancing here if i drop this bouncy ball on it you can see it easily falls off now i'm going to do the same thing but i'm just going to set a piece of paper over it i can even throw it pretty hard [Music] it literally doesn't go anywhere but just take the paper off it's gone so how is it doing this well first let's check if it's just the weight of the paper on it balancing it so let's crumble up the paper put it on the back let's try the same thing whoa nope so it's definitely not the way to the paper in fact i can probably even put a pretty significant weight on it [Music] even a roll of duct tape couldn't hold it down so if it's not the weight of the paper how does setting a piece of paper on it keep the ruler on the table well we can get a little bit of a hint when i look at the stack of papers here i have about five papers here and some duct tape let's try to pick up the top paper just like this i can't it literally just ripped let's try just one on the table more duct tape i literally can't pick it up if i do it slow i can to give us another hand let's try it on this perforated strainer here this is just some stainless steel that has a bunch of little holes through it let's try to pick up the piece of paper now easy now let's do our same experiment again so without the paper flies right off then with the paper still flies off so in this case it still flew off with the paper on it but it was a little bit slower because as the paper was coming up it has some air resistance to it and so it slows it down but it still came off the table so we know that when you try to remove the paper fast from the table it wants to stick to it and we know also that if you put some perforations under some little holes that lit in the air under it it also comes up off the table just fine so this can help us understand that it's the air pressure that's playing a role in this so when you lay a piece of paper like this on the table there's barely any air trapped underneath it but when you try to pick it up from the center like this you're increasing the volume of the air underneath you're trying to pick it up but because there's no good air channels around the edges you can't suck in any air to increase that volume and so what it does is it lowers the pressure you're increasing the volume without increasing the air inside there so the pressure goes down so that means that the pressure is lower underneath the paper and so the atmospheric pressure pushes down on it and holds it in place so basically what you're doing is creating a paper suction cup but because it's paper it doesn't hold very long and if you just do it slowly you can pick it up just fine because it gives it enough time for the air to flow in but if you do it fast then there's not enough time for the air to flow in so it can't get in there fast enough to increase the pressure so the outside pressure holds it in place you can get this to work really well if you just take a silicone mat and get a handle in the center and then try to pick it up just stuck there you can see it takes a considerable amount of force it can even almost lift up the table with it the reason i can't lift this up is because the air pressure is holding it down as soon as i try to increase the pressure in there the pressure all around under the mat becomes less than atmospheric pressure and so that just holds it in place so how do we test this for sure well it seems like all of my experiments end up this way but we need to try it in the vacuum chamber so i just have a block here and then i just have a smaller ruler that i'm going to put on the edge here then put a piece of paper over it like this then i have a steel bearing that i'm going to be dropping with a magnet so i'm going to try it once in atmospheric pressure and then once at vacuum and see if there's any difference okay first we'll do it in air three two one stays up just fine now we'll suck out the air and do it in vacuum okay now we're at a pretty good vacuum in there minus one atmospheres let's see what happens now three two one easily pops off of there look at that so with no atmosphere in there to hold the paper down the roller just pops right off so this is a pretty definitive test to show that it is atmospheric pressure that's holding the paper on there and before we end i'd like to thank endl for sponsoring this video if you ever have a hard time concentrating or falling asleep or you need help relaxing you should try endl endl is an environment-based non-profit app that takes everything we know about sound and combines it with cutting-edge technology the result is real-time personalized soundscapes designed to help you relax focus and sleep endl is informed by science created by science and backed by science this app is really cool it uses circadian rhythms your 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experiences and thanks again to endl for sponsoring this video and thanks for watching another episode of the action lab i hope you enjoyed it if you did don't forget to subscribe if you haven't subscribed to my channel yet and you can also hit the bell so that you are notified when i release my latest videos and thanks for watching and i'll see you next time

Channel: The Action Lab

Views: 1,776,427

Keywords: ruler, ball, trick, the action lab, vacuum chamber, ruler trick

Id: VI8C52ueO6c

Length: 6min 58sec (418 seconds)

Published: Wed Feb 23 2022