Can You Figure Out The Hour Glass Buoyancy Problem?

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I talk about why an hour glass floats when the sand is at the top, but sinks when it's at the bottom.

[ClaeFace]

If there’s one thing that these videos have taught me, it’s how cool magnets are

[skube]

This dude is litterly doing every single experiment we wanted to do as kids but, we couldn't.

[karma_yogi_]

well put together. he took a seemingly boring thing and turned it into a mystery

[jnhrtmn]

Vibrate the host tube walls to release the friction by bouncing off of the sides.

[TooMich]

I thought it would be something like how the center of buoyancy would be lower when the top boards fall, and it would be in slightly denser water because of the gradient and that would be enough to keep it up, then when the sand goes down the center of the points he is slightly higher

[shadykermit]

Exams ask you these kind of questions, and then teachers expect you to solve it in *3 minutes*

[Ali]

The Hourglass can actually be used as a timer to press a button underneath the water tank.

[Amira_Phoenix]

and can we just take a second to admire how nonchalantly this guy is handling his gym weights? 💪

[ripmorld]

1:36 I propose the theory of this is the sandglass wants to flip over because the center of mass is not as low as possible. As it flips over the head sketch the container wall, as the fiction generates an upward force.

[jellina]

Hi
Recently I noticed a weird thing around me
There's a electric wire outside my house, it's straight and has some slope
When it rains water droplets since it has more adhesive force moves along the wire downwards
But water droplets from the other side move upward along the wire
How this happened
I am sure the wire is straight and has a slope

[ArjenZwerver]

Is it really the friction that keeps the hour glass from sinking?

If you look at the drop on @1:50 then it looks like it's sinking first. But then the buoyancy takes over and stops the downward motion almost making it look like it wants to go up again. Maybe this is where the friction comes in to prevent that from happening?

I'm really curious what would happen when you put the hour glass in (sand in top) and then pull the hour glass down with a magnet then releasing it. Will it try to float to the top first? Or will it just stay at the bottom?


My theory was:
If you divide the hour glass up in 2 sections (top and bottom) and look at the buoyancy created by each of those sections (both without sand) you will see that the top part creates less of it then the bottom part due to the pressure differences in the water caused by a difference in depth.
So lets assume: "A section filled with sand will only provide half it's original buoyancy".
When the sand is in the top it will lose less buoyancy so it floats. When the sand is in the bottom it will lose more buoyancy so it sinks.

Would that make sense?

[CMZneu]

I thought there was something cooler going on for a second... i guess i never imagined that glass against glass in water would generate that much friction.

[bhrgv]

I click on his videos faster than my school classes 🤣

[klschofield]

I would like to see this experiment with a tube, unable to be blocked by sand, connecting the top and bottom, so as to prevent the possibility of a pressure differential, which is what I belive is causing it to float. As the vial is flipped, the motion of the sand tries to push the air out the other end, but since it's sealed, the air subsequently ends up on top of the sand just prior to the sand sealing off the choke point.

[Leverguns]

That was a really neat experience, it’s almost magical.

[kreynolds]

We can say the buoyancy is for all intensive purposes, static and unchanging. That means adding friction does not change the buoyancy. And neither would we say the heavyer than water upside down submerged hourglass is floating.

But we can say that the buoyancy counters enough of the force of gravity, so that friction may hold it in place, untill the force from the pressing on the sidewalls (created by the hour leverage action created by center of mass along an unbalanced hour glass and buoyant forces acting on the hourglass), reduces enough that that lever can no longer provide the pressure nessesary to generate the friction nessesary to overcome the downward force.

[thomashan]

Dude really knows how to teach and explain ❤️

[jbirdmax]

Fantastic presentation as always!!
You somehow always manage to keep our attention no matter how mundane the subject matter.
A true master of the craft.

[TechnoSan]

I think it has to do with some density distribution
Like the principle of ship floating
And also it has something with center of gravity
(Forgot most about it which I learnt in mechanics in last year in school 🤦‍♂️)

[mohitjain]

So impressive!!!!
I want you to make more videos as you can explain things more deeply than in shorts.