5 Fun Physics Phenomena

– Five fun physics phenomena. Number one,
have a friend hold a cane out horizontally for you, or another similar object. And putting
your two index fingers together, try to place them underneath the center of mass. When they
let go, you will find it doesn’t normally work. But now try putting each index finger
at opposite ends of the cane, and then moving your index fingers in towards the middle.
What you will find is that they always end up right under the center of mass of the cane.
You can try starting off asymmetrically and they will still end up under the center of
mass. You can try going at different speeds. Really slowly, or really fast. But you still
end up perfectly under the center of mass. How does this work? Number two, the phone
flip. Have you ever tried to spin your phone? If you do it in this direction, it’s pretty
easy. It stays nicely aligned. If you spin it along its short axis, you’ll also find
it spins very well. But if you try to flip your phone end over end like this, you can’t
do it cleanly. The phone will never flip simply end over end without also rotating in one
of the other directions. Even when I make an almost perfect flip, instabilities grow
until the phone rotates around another axis. Why can’t… No, I still can’t do it. Why
is it so? Number three, you’ve probably seen that if you rub a cup on your hair, you can
make it electrically charged. And if you bring it close to a stream of water, you can actually
cause that stream to deflect. Now usually this is used in chemistry textbooks as a demonstration
of the polar nature of water. Water is a molecule with a more positive side and a more negative
side, and so what happens, so you’re told, is that the water molecule flips around so
the positive side of the water faces the negative side of the cup and that is what attracts
the water to the cup. But this is not the real explanation. If you have a uniform electric
field, there’s an equal force pulling the positive side towards it as there is pushing
the negative side away from it. And so you can’t actually do more than just turn the
molecules. You would need a really, really strong gradient in your electric field to
make this work at all, and it basically is just not going to happen from a cup. So why
is the stream actually attracted to a charged cup? That is the question. Number four, take
a piece of your favorite cereal and drop it into a bowl of water. Then using a very strong
magnet, try to pull the cereal around. Isn’t that cool? So why is cereal magnetic? And
finally, five, the teabag rocket. Take a teabag and cut off the sealed end very carefully.
Now dump out the tea. Form the teabag into a square column. And balance it on the plate.
Now light the top of the teabag on fire. Try to light it evenly on all sides. Get ready
for takeoff in three, two, one. Ha, yeah! That is the beauty of the teabag rocket. So
why did that happen? So how do all of these phenomena work? Let me know in the comments
or make a video explaining any or all of them. Or subscribe to the channel and I’ll post
the answers next week. I hope you enjoyed those fun physics phenomena. I know a guy
who would, the former commander of the international space station, Commander Chris Hadfield. I’m
actually hosting live events with him in late August in Sydney and Canberra. I’m so looking
forward to that. Now, the Sydney shows are all sold out, but there are still as of now
tickets to the Canberra show. So if you want to come to that, check out the link in the
description. Now Chris Hadfield actually wrote a book called An Astronaut’s Guide to Life
on Earth, and I’m listening to it right now as I travel around the world, and it is awesome
because it contains great advice not only for people who want to become astronauts,
but also for everyone who wants to lead a meaningful life here on earth. And you can
download this book for free if you like by going to audible.com/veritasium. Or you can
pick any other book of your choosing for a one month free trial. Audible is a great service
with over 150,000 titles in all areas of literature, including fiction, non-fiction, and periodicals,
and so you can find virtually anything you want there. And by going to audible.com/veritasium,
they know that I sent you and they help me out to continue making these videos for you
for free. So I really want to thank Audible for supporting me and I want to thank you
for watching.

About the author


  1. Cereal is magnetic because there is iron in it. You can prove this it you crush up a cereal with lots of iron, such as nutri-grain, very finely and then run a magnet through the dust. You will find that there will be little bits of iron on the end of the magnet.

  2. At this very moment this video has 5,154,125 views, 2.147 dislike(for what ever reason ) and 65863 likes. the remaining 5,086,115 were too lazy to move a finger but still watching.

  3. Anyone else find it suss that he looks exactly to the center of mass each time well before his eyes approach it? Not saying it does not work but to me it looks like he has marked the center to remove user error making it seem much easier and more repeatable than it really is.

  4. Water molecule: the distance between opposite charges is less than distance between like charges. Coulomb’s law => for same charge, the smaller distance => greater force

  5. 1: one of the fingers is closer to the center of the mass wich means ot has more weight on it and thus there is bigger friction, so the other finger will be mving towards it. When it flips and the second finger will be closer it will have bigger mass pushing on it thus making friction bigger and then the first finger will move towards center of the mass. This repeats untill youll have both fingers under the centre.

    2: I think this has something to do with axis of rotation. When you flipp it sideways it rotates around with mass being close to its axis of rotation or mass being perfectly balanced. When you doi it the 3rd way its not perfect and it tries to balance around the other axis. Im sure it has something in common with its mass and axis of rotation.

    3: that is caused by ions in the water i believe?

    4: cereals are full off iron, wich is magnetic and it does follow the magnets

    5: hot air rises up due to displacement of hot air molecules? at some point the rest of bag that didnt burn yet becomes light enough it will fly up with light hot air.

    i hope im right :3

  6. The cane is simple, since your 2 fingers share the weight, they share the same same friction, as long as the COG is in the center of them
    …….the friction is the governor keeping the COG in the center. If one finger gets too close, it carries less weight, has less friction and the other finger pushes the cane toward it to help balance the friction, therefore balancing the load, therefore keeping COG in the center. Kids cereal is fortified with iron….that's right, actual iron filings
    …..the other ones…..no damned clue.

  7. Hadfield's book is great.

    My hypothesis on the phone rotation thing is it is not balanced top to bottom ,or lengthwise, so it is has ore mass on one side than on the other, causing a non-non-symmetrical rotation when tossed, which causes one side to be influenced by a gyration along a perpendicular axis, which leads to multi-axial occupation. That's my first guess. Or perhaps there is more mass on either side of the phone lengthwise, resulting in the same effect.

  8. Hey, you don't take the herb from the paper and burn the paper, you burn the herb with the paper and it'll launch you to the moon, duh!

  9. Just another example of how this guy loves to make pple look dumb! Shows each demonstration but doesnt explain why each phenomenon happens. If he was really trying to educate people he wouldnt say " COME BACK NEXT WEEK FOR THE ANSWERS!!"….cmon why would he do that? More youtube money from another video? Not even half the views will probably come back next week for the answers…theres no piont to that other than for financial gain (which is fine, but dont say you just do this cause you "love physics") or you get sick pleasure over watching people drool for the answer which is painfully obvious to you. But thats ok…you do you veritasium!….

  10. None of those are phenomenon except maybe number 5. Maybe not, but I just don't know either way. There are plenty of physics phenomenon that could have been in this video like a colloid which is a mixture of gas and liquid that hasn't been completely explained, and thus is a phenomenon.

  11. The first one is bcs when your fingers are not on the centre of mass the stick only touches one of the fingers allowing the other to move faster and thus making both fingers go back to the centre of mass.

  12. HAvent watched the vid where u explained these yet, wonder if the cane one has to do with moments? The tea bag one with the differences in temp of air in the bag, the water one not sure

  13. #4 might have something to do with the "4th phase of water." It's a relatively newly discovered phenomena that negatively charged particles inside of water seem to cluster close to non-water surfaces. There's a charge-less layer after that and then a layer of positive charge which creates a natural bi-pole which could act as a magnet when stimulated with another magnet and basically push the cereal along (and possibly even as work as a battery as the scientist explaining it pointed out). I'm no expert obviously, but there was a Ted talk that I watched on Youtube on the topic which was fascinating. I suggest you look it up.

  14. Number 1 utterly stupid! How does this work, you moved your fingers 🙄. Number two, I didn’t bother to go any further as number 1 was so pathetic!

  15. Number two I know: it is because of the intermediate moment of Inertia. The intermediate moment of Inertia of a body is an unstable one.

  16. For the teabag one, the fire heats up the air which causes it to be less dense than the cold air so it naturally makes an airstream upward. Because the remainder of the teabag is very light the upstream carries the teabag.

  17. I thought Veritasium was cool but then I noticed they purged their comment section of the Great Salvio's psychic musings. Shame, unfollowed

  18. Haven’t watched the explanation but I want to try and explain some of them. Cereal Is simple, most cereals have quite a bit of iron in them. The cane is because when you’re holding it you can feel where the center of mass is as opposed to when someone else is holding it. The rocket works because hot air rises, and flame wants to rise as well, but can only do so when the bag is mostly burnt cause it is too heavy to lift otherwise. I honestly have no clue how to explain the water one though. Off to watch the explanation!

  19. The tea bag is sucking in air via a vacuum caused by the heat and once the ashes get light enough for the rush of air to lift it it floats up.

  20. 1:48 Please can someone explain this. I think it is something to do with the cups charge effecting the surface tension of the water. Water molecules on the surface do not have a uniform electric field, since they only experience electrical forces pulling them sideways and downwards this makes the surface slightly more positive. And since the cup has gained electrons from rubbing its more negative. Hence the electrostatic force causes the water to bend when you place the cup near the stream of water.

  21. I sure am glad he blurred out that logo on the back of his phone. Gee, I wonder what was underneath? Maybe an android , or even Samsung .

  22. 2nd phenomena is due to stabality problem .when you flip around shorter axiz it tries to break stability but it follows a shorter trajectory but in third case it follows a ellipsoid trajectory and breaks the stability .

  23. #1: if one side goes too fast the stick will rest more on that side creating more friction and it will rest less on the other side creating less friction which creates this effect of gravity trying to correct you and unless you are just trying to fail that change in friction will be enough to let you go the right speed towards the centre of mass on both sides causing you to end up in the centre of mass.( I am not too sure about this one but it sounds logical to me.)
    #2: because the air resistance in the first one is minimal which makes it almost impossible to fail, but in the second one there is enough air resistence to require a precise throw.
    #3 yep. Idk.
    #4 oh. Well maybe I know 5.
    #5 the hot air from the fire rises and it lifts the teabag.

  24. 1
    When we move our fingers the side closer to the centre of mass of the stick moves slower due to the gerater friction . And the side for the moves faster due to the low friction which causes both the fingers to end up under the centre of mass.
    The phone flips in different Axises at the same time
    When the magnet comes close to the water its forms of inward bulges in the surface of the water due to its magnetic field and the serial falls in that bulge and when and when we move the magnet the the bulge also moves while the serial is in the bulge so it also Moves the serial with it

  25. Cereal is behaving like a magnet . Why is it so ?

    Ans: As cereals contains high iron , when getting soaked in water , this iron gets hydrated ( 2Fe+3H20= Fe2O3+3H2) and gets attracted towards the magnet . That is the wright answer.

  26. The tea bag is fly in air because the air was very hot due to fire around it and it goes upward as in hot air balloon

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