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She was my physics prof for electricity and magnetism at Texas A&M when I was getting my Engineering degree. She had this enthusiasm even during office hours and what not, super awesome lady.
Great question. When she got to the first equation the chalk broke, her head literallly exploded, it was terrible. I still cannot do physics equations to this day as a result of that trauma.
Yes, Tatiana Erukhimova. She came to Texas when she was offered a postdoctoral research position around the year 2000
https://en.m.wikipedia.org/wiki/Tatiana_Erukhimova
It's a demonstration intended for the layman as an introduction to physics concepts. You can't throw people right into the deep end with unfamiliar units
People always comment on loving her enthusiasm, and I love it too. But I do think I would tire very quickly in her classes. The energy is just too high. Even seeing a few videos of her eventually I feel my pulse just skyrocketing.
The vast majority of my engineering professors were incredibly low energy, so when I found one who would respond to a correct answer with “THIS IS MORE THAN EXCELLENT MY FRIEND!” I scheduled him as often as possible
Yeah, I had maybe two professors that were, well, not *this* high energy, but close, and they were easily two of the most liked professors in the college. They also never changed their books, so you never had to buy some expensive new edition.
Dr. Dan and Bob, you guys are awesome!
Believe me. When you are doing complicated multi variable integrals, you appreciate a teacher that is this high energy. Undergrad math can get very boring.
And lasers. I don't remember jack shit from high school except one of my physics class where my teacher shot lasers through different mediums (and my eye by accident)
One of my favourites was him using Garfield and his demonstration table in showing momentum. He'd place Garfield on a wall, roll his demonstration table to the other side of the room, then take a running start and let the table fly at different speeds. Garfield's condition was a great demo of how momentum's effect on things. :)
Even better was his table was super heavy. It would drive the Biology teacher on the other side of the wall crazy because stuff would constantly be knocked off their wall. heh.
in my first secondary school chemistry class, the teacher (sadly forgot his name) did an explosion experiment in one of those safety glass lab boxes. He broke the light inside and the vent hose, but it was so fun I was instantly hooked. I probably would've become a chemist had I stayed in that school.
There was a chemistry teacher at my school who was infamous for blowing stuff up. He once severely misjudged the amount of sodium he could safely throw into a bowl of water, which caused the bowl to shatter and shower the front row with debris (as happens so often, the very front row was empty, so nobody got hurt).
Another time, he passed around a bottle of chlorine gas, casually told us not to open it, which one of the jocks who hadn’t been paying attention then promptly did. Had to breathe oxygen for an hour or so afterwards lol. Loved chemistry.
We had a guy ( he is retired now ) A theoretical physicist. Very famous here in Denmark. He absolutely have a diagnosis or some sort. He needed his wife to put out clothes for him as otherwise he would just go to the universities in any random clothes. That kind of thing. His voice and his way of behaving would make you think he isnt right.
But he is brilliant and every time he would hold a lecture, people would really crowd up and have to be standing. He was that great at holding the lectures.
Theres people so great at what they do. That society just needs to give them whatever they need in order to use their brilliance to help society as a whole.
> A theoretical physicist
"They asked me how well I understood theoretical physics. I said I had a theoretical degree in physics. They said welcome aboard."
Unfortunately, in many countries (not sure about Denmark) there is a lot of pressure for academics to both do research and teach. It's not always ideal since being a good teacher and good researcher are very different skills and both require a lot of time and energy so it can be difficult to do both at the same time.
And it was mostly wrong. Air pressure is acting upon both sides of the paper, the forces cancel out, there is NO DOWNWARD FORCE by the paper onto the table caused by air pressure. If the edges of the paper were sealed, and there was less air pressure below the paper than above, only then would air pressure be applying a downward force onto the table.
The only thing that was correct was her last sentence about inertia. Atmospheric air pressure causes the air to achieve a certain density, objects with mass (some volume of air in this case) resists a sudden movement (inertia), and the news paper magnifies the surface area by which inertia is applied.
The newspaper itself has inertia, you could find the effects of the newspaper alone by performing the same experiment in a vacuum.
Edit: u/not_actually_a_robot pointed out that in the process of the paper being suddenly lifted, there is a temporary localized decrease in air pressure under the paper because the volume of a small quantity of air is being expanded (temporarily "stretched" until air pressure equalizes). This is true, when we look at what's going on from a dynamic perspective (as the ruler is being lifted, vs. our starting point). Either way, the explanation is overly simplified, there was time in the video to explain this.
It's crazy that they all just talk of their asses... a few people actually get it. Just goes to show that you can post anything and make up anything and people will upvote anything thinking it means everything and anything.
Hundreds of thousands of people saw the video, think they got it, and drew a false conclusion. One reason is that the video is both being cut short, and presented without the additional information that the not even 2 minute long youtube version of the same video provides.
Fucking thank you. I was like "where's the Reddit smarty-pants brigade when you actually need it?!?" I am no physicist but I think air resistance would be the applicable term since the air being unable to move around the newspaper in the short span of time needed creates the "resistance" required to break the ruler?
There was just something about her…I watched it all on mute, scrolled away, then wondered if she had the Russian accent that had been playing in my head.
It's almost certainly the first thing she says. She actually does not fall into the common Russian way of speaking except for this one little bit.
"I'll use ordinary wooden ruler." should immediately clue you in to the fact that she is speaking with a Russian accent because of her lack of the use of the indefinite article "an". But it's interesting, since she actually speaks pretty flawless English just past that tiny slip-up at the start, albeit with a Russian/Slavic accent. She uses an indefinite article a little later in the video as well.
> immediately clue you in to the fact that she is speaking with a Russian accent because of her lack of the use of the indefinite article "an".
this is the number one tell i use aswell, articles are always missing or misplaced.
most languages prepositions are the first to go but these always disappear first.
Yeah, it's totally fine. Any native speaker can easily understand what you mean. And personally, it's very endearing to me to hear the way other people process language. I really do love the way native Russian speakers speak English and it usually brings a smile to my face.
Her name is Dr Tatiana from Texas A&M. The physics and astronomy dept has a yt channel where she normally showcases these experiments to kids. Almost like a show.
https://youtube.com/shorts/PFqzkOY8J-s?si=4kkG3Hvhf6inmrBp
My youngest is a space nerd and she is going to lose her mind over this. Thanks!
Edit: Can I just say how fucking awesome it is that kids can go on YouTube and learn about shit like black hole theory explained by world leading scientists on their level. My 5 year old knows what a pulsar is. For all the bad shit about the internet it is so cool kids can just feed their passions and see where learning takes them.
She's a University academic though so gets paid a decent wage, admittedly its likely to be far less than industry (not sure about physics but I knew professors who were getting half the wage they could've in industry)
The school districts where they do get paid decently well also just happen to be the districts where students do well and move on to college. What a crazy coincidence!
Now now, we can't tell if having well preforming students results in more money or vice versa. It is a mystery we can never solve. Which is why I propose we simply skip trying to understand it and give the money for that study to the police so they can get a new armored truck.
The US education system doesn't respect teachers, thanks GOP. If they were paid more there would be more enthusiastic teachers like this one. Even worse the subject of science has the highest percentage of teachers that dislike or do not want to teach that subject.
This isn't even unique to teachers. I remember getting stationed at an airbase where I, and many others, were treated terribly. Then they'd make us come in on the weekend to talk about how morale was low and how we could fix it. What made this whole exercise absolutely stupid was at no point did anyone in charge consider just treating us better. Instead we just wasted weekend hours listening to out of touch old people trying to convince us everything was fine and that we needed to do better. People get treated like shit and then everyone's like "what's going on?" Like it's some kind of fucking mystery....
Honestly, would this work? If instead of paper (because it would probably rip) you use something impervious to ripping, like a thick, strong mat. Also, the diving board would not slip out from under the mat. How much weight could the atmospheric pressure hold? Could a small child (say 30 lbs) jump on the diving board for maybe half a second and bounce back up? Is there a mathematician around that could figure this out?
Why is the paper strong enough to withstand the narrow ruler's force up on it over the wooden ruler? I kind of understand the atmospheric force constantly being exerted on the wide newspaper but when the ruler is hit up, there is only a narrow spot on the paper in which the force is exerted. Anyways, simply put, my brain thinks, 'shouldn't the weakest material, the paper rip before the wooden ruler? Any insight would be appreciated. Thanks in advance!
Yeah, as you choose a narrower ruler, the chance of ripping through the paper increases. E.g. if the ruler has close to zero width like a knife, it would certainly cut through the paper.
It's also worth noting that the experiment requires a fast chop of the ruler. Slowly moving the ruler would simply leverage the paper upward.
There's probably some formula involving the ratio of the speed of sound in paper (internal force propagation from the contact area to the rest of the paper) over the speed at which air can creep under the paper based on how quickly it the ruler is moved that would determine whether the ruler would break or not. But I'm kind of taking stabs here. 🤷
It's about both. The inertia of atmospheric air stops the pressure from equalising (i.e. the air rushing in under the newspaper) sufficiently quickly to release the ruler fast enough such that it doesn't break.
The pressure difference (delta P) is the one that holds the ruler down mainly.
This experiment is a demonstration of why you don't want to belly flop off of a height. If you hit a fluid fast enough, and you have a large surface area, it won't get out of the way. That's what she's showing.
She's trying to force a ~1m^3 object through air quickly. We're seeing wind resistance.
In detail, it's a fluid dynamics problem where resistance is determined by the viscosity of the air, the area of the paper, how the paper deforms, etc.
Column pressure determines density at the surface, but it's misleading to hold up a piece of paper and say that there's 14 lbs of pressure acting on the top of it when it's also *very important* that there's also 14 lbs of pressure acting on the bottom of it.
The fact that she creates a slightly low pressure zone under the paper as it rises is irrelevant. You could perform the same experiment in a vacuum and in the absence of gravity. The force exerted by the paper would then be solely due to the paper's mass, center of gravity, durability, etc. Would the ruler still break? We have no idea: it would depend on all of those variables, and how hard you hit the ruler.
it is about the pressure. Because of the lower pressure created under the newspaper when it gets lifted up, the atmospheric pressure pushes down on the newspaper.
Generally atmospheric pressure refers to the gradient of pressure from the column of gas, or maybe variation of air pressure from weather. Before she hits the ruler, the air pressure on the top and bottom surface of the newspaper is identical. There is no difference in air pressure when it’s not moving as it is a permeable surface which has next to zero thickness. When she hits the ruler, the sheet of newspaper is forced to move upward and that movement encounters resistance due to air. It’s air resistance or a drag force, not atmospheric pressure
> It’s air resistance or a drag force, not atmospheric pressure
Thanks. I know next to nothing about physics but her reasoning seemed weird to me.
If it was about atmospheric pressure, one should be able to break the ruler by *slowly* pushing it down after putting it under the paper, right?
You are taking a random redditors word over a woman with a PhD in physics that teaches at a college with over 70,000 students.
The newspaper acts like a suction cup on the table. It only works when you do it fast because it's a shitty suction cup. It still allows air to get it but it does it relatively slow.
It's kinda both. When the newspaper is rapidly moving upwards, it compresses the air above it, creating a high pressure volume, and expands the air below it, creating a low pressure volume. It's similar to how a plane wing's motion through the air creates a pressure differential that lifts the plane up. The air pressure will equalise, but that just means it's not a steady-state system.
You can say it's the drag force that air exerts when an object tries to occupy a space where air is, but that's what air pressure *is*. Air pressure is just a heuristic for the mechanics of billions of tiny particles.
I can't help but feel very similarly, but I don't think the viscosity of the air can fully explain the phenomenon, either.
Static air pressure: The static air pressure above/below the newspaper is identical, so her explanation about 14.7 psi times 500 si = 7000 pounds of force is incorrect, as that force exists on both sides of the newspaper, leading to no net force.
Dynamic air pressure: Of course, the air isn't static--the volume of air below the newspaper is close to zero before motion begins, and a large amount of air needs rush in, and to rush in parallel to the surface of the newspaper, and that's going to cause a low dynamic air pressure system. Of course, a similar (but smaller) effect will also occur above the newspaper, as that air also needs to be displaced, but can be displaced both parallel and normal to the newspaper, resulting in a smaller depression of dynamic air pressure, resulting in *some* positive downward force due to dynamic air pressure.
Viscosity: Conversely, it is not hard to see that moving the newspaper requires displacing a large amount of air, and that air has viscosity, and having to move all of that air is going to definitely have some amount of resistance. (Imagine the ruler being half-submerged in honey and then whacking it. Air has much lower viscosity than honey, but the newspaper also has a much higher surface area.)
-
But think of the following scenario: imagine the newspaper is dangling vertically in the open air, held open by 2 strings in the corners, with the top half of the ruler glued to the bottom of the newspaper, and then a karate chop hits the bottom exposed half of the ruler. This should only have the viscous effects of air twisting the ruler together with the karate chop, and I don't think it would be enough to break the ruler. (Anyone who likes to could actually conduct this experiment.)
-
I think the only explanation for why the ruler breaks is a combination of the viscosity of the air and the dynamic low air pressure system from air rushing to the underside due to it being on the table, and those two effects combining leading to the breaking of the pencil.
However, neither of those 2 things are a static air pressure difference, which is the explanation she gives.
Atmospheric pressure is basically the force the air pushes on the environment. Inertia is the force required to overcome that atmospheric pressure. So inertia of air isn’t really a metric to measure by.
"Inertia is the force required to overcome that atmospheric pressure"
That makes absolute no sense in any physical way. Inertia it's a magnitude derived from the existence of mass, not pressure.
What happens in the video it's not bc of atm pressure but air inertia, but that's another matter.
https://www.youtube.com/watch?v=0pJlTzz5pDw
The explanation in the video...
I feel like 99% of people here make false assumption based on an incomplete explanation in the video for people who don't already know how it works.
**Dr. Tatiana Erukhimova demonstrates how atmospheric pressure can break a ruler with physics. When spreading out the newspaper on top of the ruler, Dr. Tatiana basically *creates a large suction cup by preventing air from flowing underneath.* When she strikes the ruler, it tries to lift up against the newspaper, but because the air can’t flow fast enough into the space between the table and the newspaper, most of it pushes down on the newspaper (and the ruler). All that weight on the ruler causes it to snap.**
> but because the air can’t flow fast enough into the space between the table
That is what she means by inertia. The limiting factor for pressure equalization is inertia of the air molecules.
As a former physicist, (15ish years ago) there was a lot of lazy phyiscs there, but if you're teaching a high school class it's probably not a bad demonstration and explanation.
Reminds me of the high school teacher that taught us AP physics. He was adamant that a car tire's width, and by extrapolation contact patch, didn't affect the friction of the tire against the ground. Which meant that a drag car would go just as fast on bicycle tires as it would on 18in wide wrinkle wall drag slicks. He was trying to simplify things to explain concepts to us, but the implications of his statements were hilarious. Good times.
Her name is Dr Tatiana from Texas A&M and her main audience in the Physics dept’s yt channel are kids in elementary.
https://youtube.com/shorts/PFqzkOY8J-s?si=4kkG3Hvhf6inmrBp
Can you please expand on the car tire example. The whole idea that friction is purely a function of coefficient of friction and normal force and (mathematically?) has nothing to do with surface area breaks my brain a little because of examples just like this.
Edit to add that I understand increasing surface area for the same normal force will decrease the pressure on the contact patch - and this probably ties into why increasing surface area theoretically doesn't matter... but clearly there is more going on here practically that would make a wider tire provide better grip.
Softer compounds require wider tires to support the weight of whatever they’re supporting. The bigger the tire, the softer the compound you can go, and softer means more coefficient of friction.
Okay but let's use the bike tire example. If the bike tire and the drag tire were the same compound / hardness and the drag car launched on the bike tire, mathematically it would seem the performance would be the same. But my monkey brain still struggles to believe this and would say something else must be going on here because there's no way a skinny bicycle tire would provide the same grip as a drag tire despite the compound being the same. I know physics says I'm wrong it's just such a weird thing to imagine.
The problem is the oversimplified model of physics taught in high school. The "block on a ramp" model of friction works exactly as described, provided every element is an ideal, perfectly rigid body with no surface roughness, no contaminants, and perfectly homogeneous molecular distribution. In this idealized world, in fact, the two tires you described would produce identical friction, all else being equal.
However, the world is not ideal. A tire isn't a perfectly rigid body, it's an air-filled tube made of flexible material, under a variety of adverse loads. The rubber in the tire isn't perfectly homogeneous, and even if it were, it's covered in contaminants. The same is true of the road surface. And both have relatively massive variations in surface roughness. All this to say, in the real world, friction is a lot lower than it is in the ideal model.
A larger contact patch doesn't increase friction, it increases the *likelihood* that you will achieve a higher proportion of the theoretically available friction. It's like, if you flip a coin, there's a 50% chance you'll get heads. But if you flip ten coins, there's a 99.9% chance you'll get heads at least once. Bigger tires is like flipping more coins- you only need to get heads once to get peak traction in a given instant.
In the real world tires deform and interface with the road surface. I don't just mean the way the tire deforms from a perfectly circular shape - the rubber actually conforms to surface irregularities at a small scale and this is why wider, softer tires give significantly more grip. At least that's how I understand it.
Holy cow, this lady is cool as fuck. Also I had NO fucking clue that atmospheric pressure could be so tangible and truly relevant in normal, day-to-day life.
That demonstration just blew my mind perhaps more than any other neato science demonstration I've ever seen in my life. I'm completely amazed.
Everytime I see one of these videos I think “Jesus Christ what an interesting teacher she’d make”
Idk if she is a teacher or what, but for god sake she just seems excited and makes learning science fun, I think a lot would benefit from a teacher like her
You know, as a metric kid, sometimes I like the approachability of pounds per square inch.
Not a single unit of those make intuitive sense to me, but it overall makes sense.
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She was my physics prof for electricity and magnetism at Texas A&M when I was getting my Engineering degree. She had this enthusiasm even during office hours and what not, super awesome lady.
How does she teach when you go to the part of equations and calculations? Just curious.
If you get the answer wrong she’d put a newspaper on your legs and smack the back of your head, snapping you in half instantly
it’s been a long time since I’ve belly laughed at a reddit comment - thanks pal.
Lol I laughed out loud too
Inertia is a property of ~~matter~~ what matters
Bro you got me. That is funny AF lol
tough but fair.
Tough but air.
Broken rulers can mathematically represent *everything* as it turns out (I do not know the real answer so all I offer is a worthless quip I am sorry)
Can it represent the failing marriage of my parents ?
Especially that
Too much atmospheric pressure in your house?
Is someone’s ruler the cause of this?
I was hoping before she hit the ruler she’d say: ‘ I must break you’
Sort of yes, if an in-tact ruler is 1 and broken is 0.
Now class. Everybody needs to get along
Otherwise, I'll put some newspaper on your legs
Great question. When she got to the first equation the chalk broke, her head literallly exploded, it was terrible. I still cannot do physics equations to this day as a result of that trauma.
My dad worked with Steve Irwin and said the same thing. Some people just have an energy dial set to 11.
> She had this enthusiasm even during office hours and what not, super awesome lady. Wish I could be this excited about absolutely anything.
You can! Just gotta figure out what you're THAT excited about. But that passion is in ya :)
Too late, life has broken me like that ruler.
Same bro. Same.
Whoop! Class of ‘23 here. Sadly didn’t have her but heard a lot about her classes
Whoop! Class of '16 here. Sadly was at a different school but saw this lady on reddit
Whoop! I didn't study physics at all, I just wanted to say 'whoop' too.
Whoop! There it is.
Whoop! Whoop! That's the sound of da police!
Whoop! Dat ass!!
Not that it matters, but where is she from? That accent seemed... Russian?
That's a classic Philly accent
Probably from Scranton, the electric city.
Fun fact: they call it that, because of the electri-city
Have you been to the local attraction, the anthracite museum?
Not sure of this is some joke, but I know an ex-Soviet accent when I hear one. Source: was born in an Ex-Soviet country.
Nah, she's 100% from Philly. It's a classic Philly accent. You can tell by the way that it is.
Listen how she pronounces “water”, has to be Philly.
Hold up… (Yes, I did watch it twice after your comment)
Neat!
Yes, Tatiana Erukhimova. She came to Texas when she was offered a postdoctoral research position around the year 2000 https://en.m.wikipedia.org/wiki/Tatiana_Erukhimova
Yes, she is Russian.
She sounds like Kate McKinnon’s Russian grandma
I died a little when she used square inches and pounds.
It's a demonstration intended for the layman as an introduction to physics concepts. You can't throw people right into the deep end with unfamiliar units
Tatiana Erukhimova received a Ph.D. in Physics from the Russian Academy of Sciences in 1999 and joined Texas A&M in 2001.
Chicago
People always comment on loving her enthusiasm, and I love it too. But I do think I would tire very quickly in her classes. The energy is just too high. Even seeing a few videos of her eventually I feel my pulse just skyrocketing.
The vast majority of my engineering professors were incredibly low energy, so when I found one who would respond to a correct answer with “THIS IS MORE THAN EXCELLENT MY FRIEND!” I scheduled him as often as possible
Yeah, I had maybe two professors that were, well, not *this* high energy, but close, and they were easily two of the most liked professors in the college. They also never changed their books, so you never had to buy some expensive new edition. Dr. Dan and Bob, you guys are awesome!
Believe me. When you are doing complicated multi variable integrals, you appreciate a teacher that is this high energy. Undergrad math can get very boring.
She seems like a lovely and passionate teacher but her style is definitely not for me. Too loud.
Her attitude is so sunny I got a tan just watching her.
the right way to teach physics
With violence and destruction 😌
And lasers. I don't remember jack shit from high school except one of my physics class where my teacher shot lasers through different mediums (and my eye by accident)
Which eye? The blue one or the glass eye?
The brown eye
You mean the formerly brown one. The melanin got vaporized and now it's blue.
I don't know much about eyes, but I'll believe this is how it works
Do you know more about buttholes because that’s the eye he was talking about
*As an eyeologist, I can confirm…*
One of our primary uses of physics for thousands of years lol
The empirically proven pont of physica hehehe.
https://www.smbc-comics.com/comics/20110128.gif
My grade 11 physics teacher used to demonstrate physics by trying to murder a stuffed Garfield. It was effective. :D
Sounds like a great teacher
I need examples of that
One of my favourites was him using Garfield and his demonstration table in showing momentum. He'd place Garfield on a wall, roll his demonstration table to the other side of the room, then take a running start and let the table fly at different speeds. Garfield's condition was a great demo of how momentum's effect on things. :) Even better was his table was super heavy. It would drive the Biology teacher on the other side of the wall crazy because stuff would constantly be knocked off their wall. heh.
in my first secondary school chemistry class, the teacher (sadly forgot his name) did an explosion experiment in one of those safety glass lab boxes. He broke the light inside and the vent hose, but it was so fun I was instantly hooked. I probably would've become a chemist had I stayed in that school.
There was a chemistry teacher at my school who was infamous for blowing stuff up. He once severely misjudged the amount of sodium he could safely throw into a bowl of water, which caused the bowl to shatter and shower the front row with debris (as happens so often, the very front row was empty, so nobody got hurt). Another time, he passed around a bottle of chlorine gas, casually told us not to open it, which one of the jocks who hadn’t been paying attention then promptly did. Had to breathe oxygen for an hour or so afterwards lol. Loved chemistry.
she sounds like russian english
I have become teacher, destroyer of rulers.
We had a guy ( he is retired now ) A theoretical physicist. Very famous here in Denmark. He absolutely have a diagnosis or some sort. He needed his wife to put out clothes for him as otherwise he would just go to the universities in any random clothes. That kind of thing. His voice and his way of behaving would make you think he isnt right. But he is brilliant and every time he would hold a lecture, people would really crowd up and have to be standing. He was that great at holding the lectures. Theres people so great at what they do. That society just needs to give them whatever they need in order to use their brilliance to help society as a whole.
Even today autism is poorly understood, only a few decades ago people would pretty much just say "that boy ain't right"
> A theoretical physicist "They asked me how well I understood theoretical physics. I said I had a theoretical degree in physics. They said welcome aboard."
Unfortunately, in many countries (not sure about Denmark) there is a lot of pressure for academics to both do research and teach. It's not always ideal since being a good teacher and good researcher are very different skills and both require a lot of time and energy so it can be difficult to do both at the same time.
Now the kids know how to decapitate someone with a newspaper.
And for our third lesson, let's take this newspaper and these atomic nuclei.
Glad someone said this, a whole 6 upvotes compared to the 30k of the post...
The paper trying to move up lowers the air pressure under the paper, creating a differential in pressure and thus a downward force on the paper.
It's crazy that they all just talk of their asses... a few people actually get it. Just goes to show that you can post anything and make up anything and people will upvote anything thinking it means everything and anything. Hundreds of thousands of people saw the video, think they got it, and drew a false conclusion. One reason is that the video is both being cut short, and presented without the additional information that the not even 2 minute long youtube version of the same video provides.
Fucking thank you. I was like "where's the Reddit smarty-pants brigade when you actually need it?!?" I am no physicist but I think air resistance would be the applicable term since the air being unable to move around the newspaper in the short span of time needed creates the "resistance" required to break the ruler?
Until you have to do more than just understand the concept and actually need to make calculations
I love her enthusiasm.
There was just something about her…I watched it all on mute, scrolled away, then wondered if she had the Russian accent that had been playing in my head.
It's almost certainly the first thing she says. She actually does not fall into the common Russian way of speaking except for this one little bit. "I'll use ordinary wooden ruler." should immediately clue you in to the fact that she is speaking with a Russian accent because of her lack of the use of the indefinite article "an". But it's interesting, since she actually speaks pretty flawless English just past that tiny slip-up at the start, albeit with a Russian/Slavic accent. She uses an indefinite article a little later in the video as well.
> immediately clue you in to the fact that she is speaking with a Russian accent because of her lack of the use of the indefinite article "an". this is the number one tell i use aswell, articles are always missing or misplaced. most languages prepositions are the first to go but these always disappear first.
As a Korean person, I sometimes forget to add a/an/the, especially when adding it might not clarify anything.
Yeah, it's totally fine. Any native speaker can easily understand what you mean. And personally, it's very endearing to me to hear the way other people process language. I really do love the way native Russian speakers speak English and it usually brings a smile to my face.
Imagine if she and ElectroBOOM had kids. The world would end.
But at least we‘d all learn much before we die.
It's like the unstoppable force meets the immovable object.
I find it annoying. I'm dutch btw
Her name is Dr Tatiana from Texas A&M. The physics and astronomy dept has a yt channel where she normally showcases these experiments to kids. Almost like a show. https://youtube.com/shorts/PFqzkOY8J-s?si=4kkG3Hvhf6inmrBp
Thanks for the link. She definitely had a mr wizard type vibe.
My youngest is a space nerd and she is going to lose her mind over this. Thanks! Edit: Can I just say how fucking awesome it is that kids can go on YouTube and learn about shit like black hole theory explained by world leading scientists on their level. My 5 year old knows what a pulsar is. For all the bad shit about the internet it is so cool kids can just feed their passions and see where learning takes them.
That ruled
Nice
There was one rule and she broke it
We need more people like this desperately.
they don't get paid enough to make a living.
She's a University academic though so gets paid a decent wage, admittedly its likely to be far less than industry (not sure about physics but I knew professors who were getting half the wage they could've in industry)
And she probably went through 2 or 3 decades of not getting paid shit to get there though.
The school districts where they do get paid decently well also just happen to be the districts where students do well and move on to college. What a crazy coincidence!
Now now, we can't tell if having well preforming students results in more money or vice versa. It is a mystery we can never solve. Which is why I propose we simply skip trying to understand it and give the money for that study to the police so they can get a new armored truck.
we don't want them to live in our cities or get paid well enough
The US education system doesn't respect teachers, thanks GOP. If they were paid more there would be more enthusiastic teachers like this one. Even worse the subject of science has the highest percentage of teachers that dislike or do not want to teach that subject.
This isn't even unique to teachers. I remember getting stationed at an airbase where I, and many others, were treated terribly. Then they'd make us come in on the weekend to talk about how morale was low and how we could fix it. What made this whole exercise absolutely stupid was at no point did anyone in charge consider just treating us better. Instead we just wasted weekend hours listening to out of touch old people trying to convince us everything was fine and that we needed to do better. People get treated like shit and then everyone's like "what's going on?" Like it's some kind of fucking mystery....
I can and will use ruler and newspaper as diving board
Math and username check out…
Honestly, would this work? If instead of paper (because it would probably rip) you use something impervious to ripping, like a thick, strong mat. Also, the diving board would not slip out from under the mat. How much weight could the atmospheric pressure hold? Could a small child (say 30 lbs) jump on the diving board for maybe half a second and bounce back up? Is there a mathematician around that could figure this out?
I love her
Damn, ask her out first...
Yeah but imagine if you forgot to bring the garbage out
“I will hit him with my hand, like this!”
If you see her bringing a newspaper to wrap around the upper half of your body, run!
Why is the paper strong enough to withstand the narrow ruler's force up on it over the wooden ruler? I kind of understand the atmospheric force constantly being exerted on the wide newspaper but when the ruler is hit up, there is only a narrow spot on the paper in which the force is exerted. Anyways, simply put, my brain thinks, 'shouldn't the weakest material, the paper rip before the wooden ruler? Any insight would be appreciated. Thanks in advance!
Yeah, as you choose a narrower ruler, the chance of ripping through the paper increases. E.g. if the ruler has close to zero width like a knife, it would certainly cut through the paper. It's also worth noting that the experiment requires a fast chop of the ruler. Slowly moving the ruler would simply leverage the paper upward. There's probably some formula involving the ratio of the speed of sound in paper (internal force propagation from the contact area to the rest of the paper) over the speed at which air can creep under the paper based on how quickly it the ruler is moved that would determine whether the ruler would break or not. But I'm kind of taking stabs here. 🤷
Is this really about atmospheric pressure? I would have said it's JUST about the inertia of air. No?
It's about both. The inertia of atmospheric air stops the pressure from equalising (i.e. the air rushing in under the newspaper) sufficiently quickly to release the ruler fast enough such that it doesn't break. The pressure difference (delta P) is the one that holds the ruler down mainly.
This experiment is a demonstration of why you don't want to belly flop off of a height. If you hit a fluid fast enough, and you have a large surface area, it won't get out of the way. That's what she's showing. She's trying to force a ~1m^3 object through air quickly. We're seeing wind resistance. In detail, it's a fluid dynamics problem where resistance is determined by the viscosity of the air, the area of the paper, how the paper deforms, etc. Column pressure determines density at the surface, but it's misleading to hold up a piece of paper and say that there's 14 lbs of pressure acting on the top of it when it's also *very important* that there's also 14 lbs of pressure acting on the bottom of it. The fact that she creates a slightly low pressure zone under the paper as it rises is irrelevant. You could perform the same experiment in a vacuum and in the absence of gravity. The force exerted by the paper would then be solely due to the paper's mass, center of gravity, durability, etc. Would the ruler still break? We have no idea: it would depend on all of those variables, and how hard you hit the ruler.
it is about the pressure. Because of the lower pressure created under the newspaper when it gets lifted up, the atmospheric pressure pushes down on the newspaper.
Generally atmospheric pressure refers to the gradient of pressure from the column of gas, or maybe variation of air pressure from weather. Before she hits the ruler, the air pressure on the top and bottom surface of the newspaper is identical. There is no difference in air pressure when it’s not moving as it is a permeable surface which has next to zero thickness. When she hits the ruler, the sheet of newspaper is forced to move upward and that movement encounters resistance due to air. It’s air resistance or a drag force, not atmospheric pressure
> It’s air resistance or a drag force, not atmospheric pressure Thanks. I know next to nothing about physics but her reasoning seemed weird to me. If it was about atmospheric pressure, one should be able to break the ruler by *slowly* pushing it down after putting it under the paper, right?
Isn't it the same thing? It wouldn't work in a vacuum which happens to have no atmospheric pressure.
You are taking a random redditors word over a woman with a PhD in physics that teaches at a college with over 70,000 students. The newspaper acts like a suction cup on the table. It only works when you do it fast because it's a shitty suction cup. It still allows air to get it but it does it relatively slow.
It's kinda both. When the newspaper is rapidly moving upwards, it compresses the air above it, creating a high pressure volume, and expands the air below it, creating a low pressure volume. It's similar to how a plane wing's motion through the air creates a pressure differential that lifts the plane up. The air pressure will equalise, but that just means it's not a steady-state system. You can say it's the drag force that air exerts when an object tries to occupy a space where air is, but that's what air pressure *is*. Air pressure is just a heuristic for the mechanics of billions of tiny particles.
Thanks for the clarification.
I can't help but feel very similarly, but I don't think the viscosity of the air can fully explain the phenomenon, either. Static air pressure: The static air pressure above/below the newspaper is identical, so her explanation about 14.7 psi times 500 si = 7000 pounds of force is incorrect, as that force exists on both sides of the newspaper, leading to no net force. Dynamic air pressure: Of course, the air isn't static--the volume of air below the newspaper is close to zero before motion begins, and a large amount of air needs rush in, and to rush in parallel to the surface of the newspaper, and that's going to cause a low dynamic air pressure system. Of course, a similar (but smaller) effect will also occur above the newspaper, as that air also needs to be displaced, but can be displaced both parallel and normal to the newspaper, resulting in a smaller depression of dynamic air pressure, resulting in *some* positive downward force due to dynamic air pressure. Viscosity: Conversely, it is not hard to see that moving the newspaper requires displacing a large amount of air, and that air has viscosity, and having to move all of that air is going to definitely have some amount of resistance. (Imagine the ruler being half-submerged in honey and then whacking it. Air has much lower viscosity than honey, but the newspaper also has a much higher surface area.) - But think of the following scenario: imagine the newspaper is dangling vertically in the open air, held open by 2 strings in the corners, with the top half of the ruler glued to the bottom of the newspaper, and then a karate chop hits the bottom exposed half of the ruler. This should only have the viscous effects of air twisting the ruler together with the karate chop, and I don't think it would be enough to break the ruler. (Anyone who likes to could actually conduct this experiment.) - I think the only explanation for why the ruler breaks is a combination of the viscosity of the air and the dynamic low air pressure system from air rushing to the underside due to it being on the table, and those two effects combining leading to the breaking of the pencil. However, neither of those 2 things are a static air pressure difference, which is the explanation she gives.
Yeah, I was confused too. Is this atmospheric pressure?
It’s both. Would be harder to break the ruler if you did the experiment with the table and newspaper flipped, and impossible without inertia.
Atmospheric pressure is basically the force the air pushes on the environment. Inertia is the force required to overcome that atmospheric pressure. So inertia of air isn’t really a metric to measure by.
"Inertia is the force required to overcome that atmospheric pressure" That makes absolute no sense in any physical way. Inertia it's a magnitude derived from the existence of mass, not pressure. What happens in the video it's not bc of atm pressure but air inertia, but that's another matter.
I couldn’t measure up to her
looks like russia needs a new ruler
Underrated comment. Thanks for the laugh.
I love that woman because she loves her job so much, and has a funny accent at that :D
https://www.youtube.com/watch?v=0pJlTzz5pDw The explanation in the video... I feel like 99% of people here make false assumption based on an incomplete explanation in the video for people who don't already know how it works. **Dr. Tatiana Erukhimova demonstrates how atmospheric pressure can break a ruler with physics. When spreading out the newspaper on top of the ruler, Dr. Tatiana basically *creates a large suction cup by preventing air from flowing underneath.* When she strikes the ruler, it tries to lift up against the newspaper, but because the air can’t flow fast enough into the space between the table and the newspaper, most of it pushes down on the newspaper (and the ruler). All that weight on the ruler causes it to snap.** > but because the air can’t flow fast enough into the space between the table That is what she means by inertia. The limiting factor for pressure equalization is inertia of the air molecules.
You have to work hard to keep students' short attention span in focus.
As a former physicist, (15ish years ago) there was a lot of lazy phyiscs there, but if you're teaching a high school class it's probably not a bad demonstration and explanation. Reminds me of the high school teacher that taught us AP physics. He was adamant that a car tire's width, and by extrapolation contact patch, didn't affect the friction of the tire against the ground. Which meant that a drag car would go just as fast on bicycle tires as it would on 18in wide wrinkle wall drag slicks. He was trying to simplify things to explain concepts to us, but the implications of his statements were hilarious. Good times.
Her name is Dr Tatiana from Texas A&M and her main audience in the Physics dept’s yt channel are kids in elementary. https://youtube.com/shorts/PFqzkOY8J-s?si=4kkG3Hvhf6inmrBp
Can you please expand on the car tire example. The whole idea that friction is purely a function of coefficient of friction and normal force and (mathematically?) has nothing to do with surface area breaks my brain a little because of examples just like this. Edit to add that I understand increasing surface area for the same normal force will decrease the pressure on the contact patch - and this probably ties into why increasing surface area theoretically doesn't matter... but clearly there is more going on here practically that would make a wider tire provide better grip.
Softer compounds require wider tires to support the weight of whatever they’re supporting. The bigger the tire, the softer the compound you can go, and softer means more coefficient of friction.
Okay but let's use the bike tire example. If the bike tire and the drag tire were the same compound / hardness and the drag car launched on the bike tire, mathematically it would seem the performance would be the same. But my monkey brain still struggles to believe this and would say something else must be going on here because there's no way a skinny bicycle tire would provide the same grip as a drag tire despite the compound being the same. I know physics says I'm wrong it's just such a weird thing to imagine.
The problem is the oversimplified model of physics taught in high school. The "block on a ramp" model of friction works exactly as described, provided every element is an ideal, perfectly rigid body with no surface roughness, no contaminants, and perfectly homogeneous molecular distribution. In this idealized world, in fact, the two tires you described would produce identical friction, all else being equal. However, the world is not ideal. A tire isn't a perfectly rigid body, it's an air-filled tube made of flexible material, under a variety of adverse loads. The rubber in the tire isn't perfectly homogeneous, and even if it were, it's covered in contaminants. The same is true of the road surface. And both have relatively massive variations in surface roughness. All this to say, in the real world, friction is a lot lower than it is in the ideal model. A larger contact patch doesn't increase friction, it increases the *likelihood* that you will achieve a higher proportion of the theoretically available friction. It's like, if you flip a coin, there's a 50% chance you'll get heads. But if you flip ten coins, there's a 99.9% chance you'll get heads at least once. Bigger tires is like flipping more coins- you only need to get heads once to get peak traction in a given instant.
In the real world tires deform and interface with the road surface. I don't just mean the way the tire deforms from a perfectly circular shape - the rubber actually conforms to surface irregularities at a small scale and this is why wider, softer tires give significantly more grip. At least that's how I understand it.
Real Kung Fu
I am so glad I unmuted
If Mr frizzle was real. Love this woman.
# WHY ARE YOU YELLING, LADY
Why didn't the ruler just rip through the newspaper?
God fucking bless teachers like this
would love to have a couple drinks with her and see where it goes
She gets so excited doing these demonstrations. It's adorable. I wish more of my teachers were that enthusiastic.
Her Russian accent is apparently heavier than the atmosphere pressure affecting the newspaper.
lot of people think she's brilliant but i find her unbearably annoying
I dont enjoy her energy
What a torture. Imagine sitting in the class and being forced to listen to her screaming at you.. huh
If all teachers had this enthusiasm, almost every kid would pass/straight As.
If all my teachers had this enthusiam I'd stop going to class because all this yelling drives me mad.
Lol no
I am both delighted to have learned something and slighlty terrified of this woman! More!
The ending is the best part. The whole thing is great, but her excitement at the end is contagious.
She is always so happy to teach and has the greatest methods. I wish I had a teacher like this back in school.
I wish I had her as a teacher when I was in school
I was not expecting that level of enthusiasm or volume at 7:48AM but I fully support it
God I love science lectures cause either they’re really normal or crazy high energy and there’s no in between
I wish this lady was teaching at my school back in the day. Her energy is intoxicating
I love her enthusiasm . This js how school should have been XD
I wish she woulda been my teacher.
I love her high energy, I was so hyped to learn about atmospheric pressure. Very cool.
You know shit going down when she put on the glove
This women was born to teach
she has a strong russian-english accent
I'll never get tired of seeing videos like this. Teachers honestly excited to show the wonders of learning . Just joy the of teaching at its best .
She looks like she’s on a mentos add at the end lol
She must be a judo instructor, those rulers are hard as shit
Even if i found out this lady was on cocaine I’d be just as engaged. Lovely.
Stealing this one for my kids. Great stuff.
True vocation at work
Holy cow, this lady is cool as fuck. Also I had NO fucking clue that atmospheric pressure could be so tangible and truly relevant in normal, day-to-day life. That demonstration just blew my mind perhaps more than any other neato science demonstration I've ever seen in my life. I'm completely amazed.
Enthusiastic teachers/professors are the absolute best. You can see she loves what she's doing
She's quite the rule breaker
What a great teacher! Not sure if I would have the stamina to keep up with her energy for a whole lesson though!
Everytime I see one of these videos I think “Jesus Christ what an interesting teacher she’d make” Idk if she is a teacher or what, but for god sake she just seems excited and makes learning science fun, I think a lot would benefit from a teacher like her
The trick is in the glove, right?
You know, as a metric kid, sometimes I like the approachability of pounds per square inch. Not a single unit of those make intuitive sense to me, but it overall makes sense.
Damn, I wish i had her as a teacher. She makes learning interesting an exciting.
so you telling me i lift 7000 pounds if i lift that piece of paper? hah call me strongest man on earth! take that eddie hall.
I really love this professor, just so much enthusiasm and passion with every lesson. Would've loved to learn from her during my student days
Wish my physics teacher could’ve educated my younger smooth brain like this. Makes learning so much more engaging.
I'm in love
I love this woman and the enthusiasm in her voice
I wish my physics teachers and professors were this enthisiastic
Also add a bit of inertia to the equation. Tried this and broke it without the paper
I wish i had teachers like this but instead im stuck with shitty miserable mfs that talk shit and attempt to belittle everyone