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Can You Figure This Out?

  • Published on Aug 24, 2022 veröffentlicht
  • Shop for science gear here: theactionlab.com/
    Does an hourglass weigh more when the sand is at the top?
    See the full length video here: clip-share.net/video/Pf1W7NRahZU/video.html
    Subscribe to my other channel here: clip-share.net/user/TheActionLab

Comments • 2 074

  • Dib Irken
    Dib Irken 3 months ago +11649

    You see, mister. I never asked these questions my entire life and now here I am having answers to questions I never asked. 😭😭😭

    • Raka Bukhari
      Raka Bukhari 3 days ago

      Basically every scholar in this world

    • Fred Lee
      Fred Lee 8 days ago


    • Sander
      Sander 2 months ago

      Best comment

    • Wooper Man
      Wooper Man 2 months ago +1

      Why are you crying then?

    • JV
      JV 2 months ago

      But why are you crying?

  • Christian Domenech
    Christian Domenech 3 months ago +2586

    I can’t believe he weighed it twice and I was watching like it was really gonna weigh different the second time…

    • Egor Leontev
      Egor Leontev 13 hours ago

      Well believe cos thats how u do science.

    • Jeffrey Alilin
      Jeffrey Alilin Day ago

      He has trust issue...

    • GloryThirsty
      GloryThirsty 12 days ago +1

      @Jjh Hand k glad someone said it

    • Captain HD
      Captain HD 13 days ago

      @Tucker Garcia Weight doesn’t vary with acceleration. This is a tiny hourglass. Gravity will not make any noticeable differences on that scale so g will remain constant.

    • Tucker Garcia
      Tucker Garcia 13 days ago

      @Captain HD wrong. Same total MASS. Weight varies with acceleration

  • Dallas
    Dallas 3 months ago +475

    For a second I was screaming about how weight of something isn't buoyancy but I was pleasantly surprised by you showing us after viewing the rest of the video

    • Alex White
      Alex White 7 days ago

      @Thomas Asche Landing sand is not weightless though. Actually since it has a velocity the fall should let it collect a little extra force to exert on the bottom. The transfer of potential to kinetic energy should add a little more downward force (weight...ish)

    • A User
      A User 13 days ago

      @Furbait Not really. In the context given, weight determines buoyancy, as the volume is presumed to be constant (I don't see the hourglass changing size). That's why Action Lab said "the weight isn't changing" instead of "the density isn't changing." It's presumed that the volume is staying constant.
      Edit: also, that's a really overused and dead joke

    • Furbait
      Furbait 13 days ago

      Wow. Youre the first american that knows the absolute basic facts. Congrats

    • Thomas Asche
      Thomas Asche 2 months ago

      Falling sand is weightless 😄

    • Hakase
      Hakase 2 months ago

      The solution is in weight. Mass isn't changing, but weight is. If you count friction as a part of a weight (it is)

  • Arnold P. H.
    Arnold P. H. 2 months ago +1

    I was waiting for the hourglass to flip over, and also knew it'd float when the bottom side were empty, because of the gas supporting the entire hourglass and cancels out the weight of the upper half... Not a hard question, but definitely interesting! 😆

  • IIVQ
    IIVQ 8 days ago

    It's interesting the two versions of the hourglass weigh the same. With the sand at the top, some sand is floating in the air and not weighed. But this is balanced by the extra downward pressure of the falling sand of the bottom of the hourglass (which translates to weight on the scale).

  • sincitybighed13
    sincitybighed13 2 months ago +7

    I literally use this method when moving boxes at work. Put the heavier box on top and it literally feel lighter.

  • Avery Andronyk
    Avery Andronyk Month ago

    Wow what a great way to demonstrate friction! I never would've expected it to be that powerful

  • David Clark
    David Clark 2 months ago +29

    I appreciate that you put the answer in the short, not just in the original video. Nice

  • Lampe2020
    Lampe2020 19 days ago +1

    Very interesting!
    Without you explaining it I couldn't wrap my head around that so easily...

  • Kono Veldora Da!
    Kono Veldora Da! 3 months ago +5046

    Sandman be like: *This man is dangerous.*

    • Adrian Vanegas
      Adrian Vanegas 2 months ago +2

      Get it cause sand

    • patro m
      patro m 2 months ago

      @Earthling that being said I'm still on episode 7 I think. Haven't watched it for some time now..

    • patro m
      patro m 2 months ago

      @Earthling coz I'm tired of seeing dudes making out in almost every tv series.. When it was just girls I didn't mind and I know I'm hypocrite for that, but I seriously don't like having to watch dudes making out. And I'm not alone in that.. There's to much unnecessary sexual scenes in holywood already..

    • Earthling
      Earthling 2 months ago

      @patro m wow, I didn't even notice that gay couples were majority. Also, Barbie and Ken are not gay. Why do you have to tune it out though?

    • patro m
      patro m 2 months ago +1

      @roach under a can I love it too, but I have to tune out that every single couple in the is gay 😂the only straight couple is the one with child locked in the basement 😂

  • Sumit Pardeshi
    Sumit Pardeshi 3 months ago

    Man! Hats off to your endeavours fueled on your determinations, consistency and raw passion towards science.
    Love fades out; passion dont.

  • AnyasCelticCreations AtEtsy

    This is exactly the kind of thing that I used to do for show and tell as a kid. I love these! 👍

  • Jjh Hand k
    Jjh Hand k Month ago +2

    Technically, it does weigh more. It's closer to the center of earths gravity, which as explained by Einstein, makes it heavier.

  • couu alis
    couu alis 2 months ago

    This guy never runs out of content and things to amaze me with!

  • Stefan
    Stefan 3 months ago +1749

    So basically at the start of video, he deliberately showed the side of the cylinder from where we wouldn't see it trying to topple and hence friction.

    • Jay Jones Jeans
      Jay Jones Jeans 13 days ago +1

      I saw that too (on my second watch). It took a min to realize that was the "trick".

    • Curtis Childress
      Curtis Childress Month ago

      Bottom empty half is buoyant & floats.

    • Stefan
      Stefan 2 months ago

      @ASMR Enjoyer Your dumbness, I got it right

    • ASMR Enjoyer
      ASMR Enjoyer 2 months ago

      Excuses. I got it right.

    • Alex
      Alex 3 months ago

      @PLisskin thank you for being the only decent individual. Relax

  • Hiru Harada
    Hiru Harada 3 months ago

    Since it's at such a delicate balance already, there may also be enough weight removed from the minute-glass while sand is falling to allow it that extra little buoyancy needed. I don't know if it's countered properly by the constant collisions at the bottom. We need to try it with the center closed, or something else similar in shape and proportions.

  • Emily Brackett
    Emily Brackett 27 minutes ago

    How cool! You always shock me with you're science experiments.

  • ScarletFlame101786
    ScarletFlame101786 3 months ago

    This reminds me how one man figured out that a rock can weigh almost half its weight in a submerged cave. But a air bubble can dislodge the rock making it no longer supported by the mass of the water it drops now its full weight.
    Perhaps to a degree the air under the sand when its at the top is able to make the sand lighter. When air goes to the top of the hourglass the sand is now at the bottom and at its full weight. Normally with the shape of the glass it will try to flip but what would happen if the hourglass was not able to flip over? What if we made it a cube or just two compartments one sand and one air. Tie something to the bottom to stop it from tipping. It should float. But if the sand weighs the same it shouldn't be able too. Its the force of buoyancy pushing up against the weight of the sand.

  • Aaron Garcia
    Aaron Garcia 2 months ago

    So basically a few things. When the sand is on top it’s converting some of the downward force into torque to flip it which makes it harder to go down, in addition to friction if it’s touching the glass. Another reason I think it may not sink when the sand is on top is because of buoyancy being stronger under higher pressures than lower, exerting more upward force than when the sand is on the bottom.

  • Steven Navarro
    Steven Navarro 6 days ago

    It's crazy everyone had their own theory why it happened. I thought the sand moving downward was mass moving which would propel it upwards.

  • John
    John 3 months ago

    While I agree with your answer here, I think one could argue that the weight would be different as, while the mass does not change, the center of mass is farther from the center of the earth, the force acting on it would be smaller and the hour glass with the sand at the top would technically be lighter (with the base at the same elevation)

  • Sam Ahadi
    Sam Ahadi 2 months ago

    The weight of the hourglass while the sand is flowing actually fluctuates and changes ever so slightly which is SUCH an interesting phenomenon

  • evifnoskcaj
    evifnoskcaj 2 months ago +1

    Also, the center of mass needs to be taken into account as well. Cool video!

  • Barsiel
    Barsiel 3 months ago +1708

    This is actually an excellent way of showing of physics (buoyancy and center of mass examples).
    Buoyancy for the forces allowing it to float, as well as how changing the center of mass changes how heavy/how much force something has at one specific point)
    Pretty cleaver my dude 👏🏼👏🏼👏🏼

    • goldenglove 85
      goldenglove 85 Month ago

      @AJ pretty sure they are explaining it like this for others that don't know it so well.. Also, a way of expressing that they themselves understood it.. Kind of saying it out loud, in other words...But I guess you just understand everything.. Must be wonderful to be genius at everything. To be so much smarter than everybody else.. With those smarts, the last place you should be is in Clip-Share comments section, belittling someone else.. 🤷🏼‍♂️ I have nothing more to say on this

    • AJ
      AJ Month ago

      thanks for pointing out the Archimedes Principle in this, i thought it was pretty obvious 😭

    • Cooper
      Cooper 3 months ago

      Your comment kind of confuses me, this feels more like a sneaky friction demonstration than one on buoyancy or COM. The buoyancy and center of mass portions were pretty intuitive but he totally got me on the friction I would not have expected friction to effect this at all besides the negligible water portion

    • goldenglove 85
      goldenglove 85 3 months ago

      @Cat OfDeath I figure lol

    • Cat OfDeath
      Cat OfDeath 3 months ago

      @goldenglove 85 The “:P” makes it obvious my comment was a joke.

  • The Random Dude
    The Random Dude 2 months ago

    I would say yes, it does weigh less, since some of the grains are in free-fall and thus effectively weightless. It's just not enough of a difference to matter in this case, or be easily measured.

  • Ben Noble
    Ben Noble 2 months ago +1

    It also technically is lighter, although the difference is immeasurably slight, because more of its mass is farther from the Earth’s center of gravity. Obviously it’s not enough to show up here, though.

  • Lord Phullaut O'Sear

    Same principle as a heavy keel on a ship; the concentrated mass makes it hard to flip over.

  • Loominardy
    Loominardy 3 months ago +1

    Technically it still weighs the same. The only difference is that the buoyancy force is stronger when the sand is on top.

  • Yusuf Pekshan
    Yusuf Pekshan 3 months ago +329

    Interesting thing to know thanks for the easy explanation ❤

    • EaglesQuestions
      EaglesQuestions 3 months ago

      It only needed an explanation because it was a lie. "Flip it over and you can see that it floats..." No it freaking doesn't -- It's just positioned to hide the fact that it's pressing itself against the sides.

  • Intellectual Iconoclasm

    This would be a great way to help kids visualize entropy. Upside-down is higher entropy than settled, more potential left. But the second it flips to a lower entropy state it just plummets.

  • Gabriel Sylvestre
    Gabriel Sylvestre 2 months ago

    Can you make a really tall hour glass so there is a substantial amount of sand falling. Will it weigh less while the sand is falling verses when it’s all at the bottom?

  • Cha
    Cha 2 months ago

    You can visualize it better when you've realized that both air and water are fluid, so they a lot of similar properties than you think. When you drop an object (without the water part), the heavy part of the object almost always go to the bottom.

  • Charles Hoskins
    Charles Hoskins Month ago

    I would say two things are happening simultaneously, air is moving up the glass as the sand falls, and the upward movement keeps the glass afloat. at the same time, gravity is affecting the sand which is falling, but not the glass itself, therefore, the glass is set in a stable position.

  • wolfko3
    wolfko3 3 months ago +35

    This guy never runs out of content and things to amaze me with!

    • Mark Rodrigue
      Mark Rodrigue 3 months ago

      Think when he was four what kind of questions he asked he’s mom why corn sinks in the pot of water but when it’s in a turd it floats In The toilet

  • Karl Hendrikse
    Karl Hendrikse 3 months ago

    Technically, it does weigh less when the sand is at the top (i.e. while sand is falling). The grains of sand that are falling at any moment are not contributing to the weight. When you're falling down an elevator shaft, your weight isn't being conveyed to the building's foundations, but it is before you leap and after you splat.

  • Tobblesmash
    Tobblesmash Month ago +1

    Also, floatation in a medium like water or air has nothing to do with mass, it'll weigh the same regardless. It's all a game of density

  • BlackHawk4832
    BlackHawk4832 2 months ago

    Well actually yeah, it could weigh less while sand is traveling through. Since the falling sand is in freefall it does not push against the scale. Question would be, is this mitigated by it's applied force when it hits the bottom.

  • Reef Randall
    Reef Randall 2 months ago

    There's actually also a second answer. It has to do with pressure. With more air lower in the tube there's a greater pressure pushing the tube upwards but when the sand replaces that buoyant air at the bottom there's less pressure pushing up because the air at the top is less buoyant than the air at the bottom

  • Jacob C
    Jacob C 3 months ago +885

    "Have you ever wondered what would happen if I did this? No? Well too bad, I'm showing you anyway!"

    • Redwan Hossain
      Redwan Hossain 2 months ago

      Me while dropping a child from top of a building:

    • Olorile
      Olorile 3 months ago +2

      @Jacob C "So you wanna hear a story eh? No? Well too bad, I'm telling you anyway" is the intro to borderlands 2 it instantly reminded me of it lol

    • Jacob C
      Jacob C 3 months ago

      @Olorile Did I accidentally make a reference to something???

    • Olorile
      Olorile 3 months ago +3

      Marcus from bdl2 is that you?

  • Andreas B
    Andreas B 3 months ago

    As weight is measured as the force excerted by the attraction between two masses divided by their distance squared. (F=G x m1 x m2 / r^2)
    Therefore it actually weighs more if the sand is at the bottom. However, the difference is miniscule for such low distance and the reason of it dropping is correctly explained

  • Irelae
    Irelae 3 months ago

    It would be cool to make an hourglass in a small water-filled tube that you could flip over on either side and have a similar effect

  • ashok kumar
    ashok kumar 2 months ago

    Tying the metal at the centre of the hour glass so that you dont have to flip the cylinder beaker to take it out every time is smart so that you can use magnet to get it out. I will never thought of that. I wouldve just use a long stick or something to take it out. Thank you for your video.

  • Malta
    Malta 29 days ago

    I knew it wouldn't be the weight, but you still set up that assumption very impressively. The first shot of it "floating" does not appear to indicate what is actually happening, clever camera work.

  • Victor Campos
    Victor Campos 3 months ago +3

    Imagine an hourglass like this but with an extreme high height (1 Mile for example).
    If you measure the total weight of the hourglass, does it count the sand that is still falling through the air or does the weight vary?

    • The Jovian
      The Jovian 2 months ago

      It counts all of it because the sand still acts on the air within the hourglass which acts on the hourglass

  • Vaishali Sharma
    Vaishali Sharma 2 months ago +1

    This is a classic case of a rhetorical question. He asks the question and answers it himself. But I must add , the videos are fun to watch.

  • Andy J
    Andy J 3 months ago

    @action lab. I partly disagree with the hypothesis.
    While the sand it at the top, a small mass of sand is falling between the orifice and the bottom of the glass. This sand isn’t supported by the hour glass meaning it’s actually lighter until the sand flow slows/stops.
    What does a scale read if you let the hourglass run on a scale?

  • TwilightDusk
    TwilightDusk 2 months ago

    It's just a buoy lol but I always loved this idea on a bigger scale like an underwater floating city perfectly balanced on air.

  • AwTickStick
    AwTickStick 3 months ago

    I figured it had something to do with the center of mass. But I also thought buoyant forces were at play. Didn't think about the sides of the graduated cylinder. Well played.

  • Heath Wilbur
    Heath Wilbur 2 months ago

    It's called, buoyancy. It's the same concept we use to make steel ships float, like destroyers and aircraft carriers. A "U" shaped section of trapped air will always try to push to the surface to equalize the pressure. Supporting some or all of the weight that is preventing the air from rising to even out the pressure.

  • Oliver Chan
    Oliver Chan 3 months ago

    I just absolutely love how it floats at first but then starts to sink as it reaches the halfway point… it’s so satisfying lol

  • Mr.X
    Mr.X 2 months ago

    Technically, the sand really weighs less when it is on top because it is then farther away from the earth's core. But the difference is veeeeeery small.

  • extremefabi
    extremefabi 2 months ago

    As some mass of sand is falling when its on top, it has to be a little lighter. Should be clearer with big hourglass.... But there is also the impact of the sand adding to the weight..... Difficult question, bigger models and equations needed 😉

  • Cheesy Danish Gaming
    Cheesy Danish Gaming 2 months ago

    This is relative to the center of mass
    It weighs the exact same no matter the location of the sand in the hourglass
    In water if it’s on the bottom it sinks due to the center of mass being at the bottom rather than at the top
    If you flip it it floats for as long as enough grains of sands remain in the top portion (and the container is small enough to keep it stationary otherwise it’ll try to match the density of water and flip over)
    However if you were to have an equal number of grains of sand in both compartments and sealed the hole so the sand won’t flow the container won’t try to flip or rather it will but it’ll stop once it turns horizontally and float at the top of the water
    So for the question it still weighs the same but center of mass makes all the difference when it comes to buoyancy
    Kerbal space program is a great teacher in physics

  • Aaron Clyburn
    Aaron Clyburn 2 months ago

    You technically also have a difference in weight due to gravity. Gravity is (m1xm2)/dxd. The distance between them is different and therefore the weight is different, but to such a minute degree that it doesn't show up on your scale.

  • DeamIT
    DeamIT 2 months ago +1

    I dont think its entirely the friction you get more buoyancy when the air is deeper than the sand. Ever pushed a ball down in the water? The deeper you go the harder it gets

  • Magic of Jafo
    Magic of Jafo 3 months ago

    When you take a mass higher in altitude, it weighs less. So yeah, the hourglass with the sand at the bottom does weigh more than with the sand at the top.

  • B the Master
    B the Master 3 months ago +116

    Finally a clip I figured out right away, I am not stupid after all :)

  • James Wisniewski
    James Wisniewski 2 months ago

    I said NO, because I knew it always weighs the same. I knew that it would flip and I honestly didn't think friction was the reason, but the loss of weight from the free falling sand. Falling sand has NO weight in 1g, as it's falling at the pull of 1g. See my thoughts? The overall object weight never changes when it's not moving, but when the sand is falling, the weight is SLIGHTLY reduced. If the scale was precise and could measure fast enough, you would see a change (actually fluctuate) with each grain dropping.

  • Alejandro Echeverria
    Alejandro Echeverria 2 months ago

    My guess is density of the water changes as the pressure increases, when the sand is on the upper side its more dense so it wants to flip, sense it can't, the air side is less dense than the water so it keeps it buoyant.

  • Alex24757
    Alex24757 25 days ago

    The weight of the hourglass is actually bigger when the sand is on the bottom. Not by any measurable amount. But when the sand is on the bottom, it is closer to the earth's center and so it is attracted by a bigger force. As a result the weight (force) of the hourglass is bigger when the sand is on the bottom. The _mass_ of the hourglass is the same of course.

  • Micah Y.
    Micah Y. 16 days ago

    It actually does weight a bit less as there’s a constant amount of sand in free fall removing steady weight from the whole. That effect is negated by the pressure the sand is placing on the bottom with its momentum, but that’s not true weight. If you had a very tall glass where all the sand stayed in free fall before hitting the bottom, you’d see the scale drop down to the weight of the container before gaining the weight back as the sand started hitting the bottom. So basically the weight would be the total weight minus the amount in free fall until the timer ran out. Unless I’m missing something

  • Mary Kay
    Mary Kay 3 months ago +4

    You are such an interesting teacher. You don’t make me feel as ignorant as I did in high school. I still can’t answer your questions. I just don’t feel as ignorant.

  • MisterPyOne
    MisterPyOne 2 months ago

    Technically an hourglass weights more when the sand is at the bottom, because more mass is nearer to the earth and the gravitational pull is greater, but it's a negligible amount

  • Thomas Friedl
    Thomas Friedl 3 months ago +1

    Technically its weight is a tiny bit bigger when the sand is at the bottom because it is closer to the core of the earth so gravity is stronger

  • dilik mli
    dilik mli 2 months ago

    Love all the content you are making!

  • Allen Bitzer
    Allen Bitzer 2 months ago

    Because floating is a matter of density relative to what you’re trying to float in, not weight. The distribution of weight across the hour glass effectively changes its density as the sand moves.

  • tal landes
    tal landes 3 months ago +4

    Dude. I just love your videos. I learn so much in just 60 seconds

  • Jahangir Shah
    Jahangir Shah 6 days ago

    The real reason behind it is that when the sand is on top the bottom section has a lot of air which tries to move up pushing the sand up so less sand weight is put on the hour glass and the glass feels light and doesn't sink. When some of the sand falls down it allows some of the air to move up into the upper part. Now the sand in the bottom has no air under it pushing it upwards so its full weight is on the glass and so it starts sinking due to weight

  • John Palmer
    John Palmer 29 days ago

    As the sand is falling through the air it actually doesnt weigh anything, so if you used an accurate enough scale, say that measured to say the ten thousands mark, or .0001 you would see the weight changed at the end of its run through the hour glass.

  • Luce Dice
    Luce Dice 2 months ago

    Technically it does weigh more because gravity is stronger the closer you get to the earth
    But I'd be surprised if it was measurable

  • MDA
    MDA 3 months ago

    Also yes if your measuring device is sensitive enough (which would be almost infinitely sensitive) if it were “sensitive enough” it would weigh more when the sand was at the bottom because that sand would be closer to the gravitational source
    I think 🤔

  • michael schwartz
    michael schwartz 3 months ago +11

    His channel is full of crazy stuff! How do you come up with this?! Please don't stop!!

  • Cranky Bonnie
    Cranky Bonnie 3 months ago

    Technically it weighs more when sand is at top due to potential energy. It's tiny difference though.

  • Eton *non fevrieat
    Eton *non fevrieat 3 months ago

    This is actually an excellent way of showing of physics (buoyancy and center of mass examples).
    Buoyancy for the forces allowing it to float, as well as how changing the center of mass changes how heavy/how much force something has at one specific point)
    Pretty cleaver my dude

  • Tinkle Me 4 [S]E.X
    Tinkle Me 4 [S]E.X 3 months ago

    This is actually an excellent way of showing of physics (buoyancy and center of mass examples).
    Buoyancy for the forces allowing it to float, as well as how changing the center of mass changes how heavy/how much force something has at one specific point)
    Pretty cleaver my dude

  • Bonolo Ntapu
    Bonolo Ntapu 3 months ago

    It's always nice to guess a science question correctly.

  • Vesperitis
    Vesperitis 3 months ago +86

    One of these days I just want the answer to be "IT'S BECAUSE I'M A WIZARD BOW DOWN TO MY POWER"

    • Curtis Childress
      Curtis Childress Month ago

      I'm an alien construct...ask/tell me anything.

    • D1NNAA
      D1NNAA 2 months ago +4

      I'm waitin for that video

    • Chad Kakashi
      Chad Kakashi 2 months ago +5

      That’d be amazing.

  • dominuspopuli
    dominuspopuli Month ago

    I suppose that it weights insignificantly less when the sand is at the top due to the mass displacement due to distance to the ground. same reason it would register with a different weight on at the poles compared to the equator, or sea level to mountain top :)

  • thokk10289
    thokk10289 3 months ago

    Technically the timer weighs a fraction less with the sand at the top than it does at the bottom. I do really mean a fraction... Repeat weighing it with a theoretical 10km long timer and you will see a difference

  • Marc Montalvo
    Marc Montalvo 2 months ago

    Techincally the sand up top is farther from earths center of gravity, therefore experience less pull due to gravity i.e. weight. So a more sensitive scale (maybe coued woth a talled hourglass) should show a difference in weight

  • Kitsune Fyora
    Kitsune Fyora 3 months ago

    This channel is a representation of those scientists who answer questions and get paid for things no one in the world thought of

  • Jordan Small
    Jordan Small 3 months ago +4

    Dang. I was getting all complicated, thinking that the sand is free fall was causing it to weigh less and therefore float until not enough sand was in free fall so it started getting heavy again.

    • F V
      F V 3 months ago

      I do actually think that what you say is true... now I wan't to try on my own...

    • Karthikeyan Manoharan
      Karthikeyan Manoharan 3 months ago

      But the little bit of sand that's in free fall exerts a greater force on the bottom of the glass than at rest. We can complicate it how much ever we want.

    • Karthikeyan Manoharan
      Karthikeyan Manoharan 3 months ago +1

      I was thinking the same

  • Sarhc Bannitoot
    Sarhc Bannitoot 3 months ago

    It’s about buoyancy of air and where it is in the glass. When it’s at bottom that means most of the mass is underneath the pocket of air and drags it down. When it’s above the buoyancy of the air is greater than the mass of sand and thus holds it up.

  • Grant Harper
    Grant Harper 2 months ago

    This is actually a little unfair due to the camera angle. I already knew the answer, but I was confused when I saw that the hour glass didn’t tilt and lean against the sides when the sand was in the top. The perspective was skewed and hid what was happening from the viewer. Regardless of intention, you mislead the audience into thinking the hourglass was still upright. You may argue “the experiment usually takes place using an hourglass with a diameter that is only 5mm shorter than the internal diameter of the container full of water. Because of this, the viewer wouldn’t be able to see the hourglass tip anyway.” Well, yes and no. Viewers typically trust the camera man to show them all of the information they need to understand what’s going on. Most people would assume that if the hour glass was trying to tip over then it would be clear in the footage presented. Here, it seems almost intentionally obscured. Maybe this was done to emulate the conditions of the experiment and the questions / mystique instilled in observers of the 5mm-difference-in-diameter version of the experiment? Whatever the case, it matters little. The strangeness of the anomaly is overshadowed by the magic of camera angles.

  • thisxgreatxdecay
    thisxgreatxdecay 2 months ago

    Doesn't it technically weigh slightly more (even if it isn't enough for an insufficiently sensitive scale to measure, or enough to affect buoyancy) when the sand is at the top, because it has more gravitational potential energy? The same way a wound clock has slightly more mass than a clock that's wound down?

  • Aris
    Aris 2 months ago

    I mean i guess theoretically if the hourglass is tall enough it should "weigh" less because most of the mass is further away from earths center of mass and the force applied to it shouldnt be as big as if the sand was at the bottom
    No idea how tall it would have to be to make a noticable difference though

  • DreadlyKnight
    DreadlyKnight 3 months ago +22

    I went from “impossible” to “oh its just friction”

  • Antioch Archives
    Antioch Archives 3 months ago +1

    This man is always answering questions I never even knew I had before

    • laernulieNlaernulieNlaernulieN
      laernulieNlaernulieNlaernulieN 2 months ago

      Have you ever wondered why you've never asked these questions?
      I'll tell you the answer in a Clip-Share short.
      Don't tell anyone else, but the answer is because they are stupid questions that nobody cares about apart from the person making a video and earning money when dummies like us watch them.

  • Sam Schellhase
    Sam Schellhase 3 months ago +2

    Honestly I thought it was a buoyancy thing, but the friction thing is cool too

    • Curtis Childress
      Curtis Childress Month ago

      Bottom empty half is buoyant & floats...try this using other containers. A heavy upper container with wider construction will evenly balance & float with an empty smaller bottom. My great grandfather built boats.

  • Luca Moriconi
    Luca Moriconi 3 months ago

    Technically it should weigh more with the sand at the bottom since it's a little closer to the ground so gravity should be stronger. Not even close enough to make any noticeable difference though

  • Pandu POLUAN
    Pandu POLUAN 2 months ago +8

    So glad you explained it at the end. I was already wide eyed and went, "WHAT WHAT"

  • Adam
    Adam 3 months ago

    I would have guessed that while the sand is emptying, some of it is in freefall, so it's not contributing to the weight. But I guess the amount of sand in freefall is insignificant.

  • nkr dinla
    nkr dinla 2 months ago

    This is a classic case of a rhetorical question. He asks the question and answers it himself. But I must add , the videos are fun to watch.

  • Nicolas Ferreira
    Nicolas Ferreira 2 months ago

    When the sand is moving from the top to the bottom,the is a period of time that the sand is in the air and not weighing on the tube. So yes while running it should in theory weigh less😁

  • DogTurtle
    DogTurtle Month ago +1

    The hourglass does lose weight when you flip it because most of the mass becomes farther away from the center of earths gravitational pull, it’s just so little that there is basically no change

  • dainiu
    dainiu 3 months ago +25

    When the sand is at the top it floats, versus when it's at the bottom.
    Which is why we have a breast stroke in swimming but no ass-stroke.

    • Arun Kumar
      Arun Kumar 3 months ago


    • David Guthary
      David Guthary 3 months ago +1

      We don't have an "ass-stroke" because our arms don't bend that way naturally.

    • Naresh Kumar
      Naresh Kumar 3 months ago +5

      Wth 😂

  • Brody M
    Brody M 3 months ago

    I had the thought. You could make a depth charge off this principle couldn't you? And know exactly how deep it would go before detonation

  • The Basketball Historian

    If I had a teacher like this in school, I'd be focused 100% all the time. 😳

  • Mikal Rage
    Mikal Rage Month ago

    It DOES weigh more when the sand is at the bottom. More of the mass of the closed hourglass system is located deeper in the gravity well of the Earth where the gravitational field strength is stronger. If this *wasn’t* the case, the sand wouldn’t fall to the bottom. The fact that the sand is drawn to be closer to the Earth’s Cg proves that the weight is increasing.

  • The Momaw
    The Momaw 18 days ago

    Wouldn't it weigh very slightly more while the sand is falling? Since gravity is accelerating the sand particles while falling and then they hit the bottom, decelerating and imparting a force