(jug gurgling)
- This is a Gluggle Jug and it's absolutely the best way
to serve water to someone because of the funny noise
that it makes.
(jug gurgling) (water sloshing)
It's good, isn't it.
I really wanted to know what was going on inside
when it made that noise.
It's obviously something to do with
the fact that you've got some air trapped in there
and how the water interacts with that,
but I wanted to know the details
so I went online and I was surprised to find
there's not really anything out there,
there aren't any diagrams, or animations,
you can't even buy one of these things made of glass
so you can see what's going on inside.
So I decided to do some of my own investigation.
My first thought was that it's related to the fact
that you can smash the bottom of a glass bottle
by striking the top.
That subject was covered comprehensively
in a Mark Rober video, I'll leave a link to it
in the description, but the short explanation
is that as the bottle moves downwards,
the inertia of the water inside
creates a cavitation bubble at the base,
it's a near vacuum inside that bubble
so the water rushes back in at high speed
and as it strikes the glass bottom, it smashes.
Ultimately I think that line of reasoning
is a bit of a distraction, but you know,
I'd filmed it already, and it's cool,
so it's in the video.
Actually, the Gluggle Jug reminds me more of
that thing that happens sometimes
when you're drinking water from a glass
and the conditions are right
so that when you tilt the glass away from your mouth
a jet of water sprays out and hits you in the face.
Does that ever happen to you?
I mean, it's happened to me
maybe three times in my life ever, so it's very rare,
but I do remember a sort of glug sound that goes with it,
or a gloip sound reminiscent of the sounds
you get from the Gluggle Jug, gloip.
So, maybe this jug is able to create that effect
in a very reproducible way,
like maybe that's what's happening
inside the tail every time it glugs.
The drinking glass splashback-effect,
seems to be easier to produce in a glass
that has a wide top and a narrow bottom.
Here, look, as the glass is tilted back,
that large body of water is channeled into a smaller area
as the cross-sectional area
of the flow of water goes down,
the speed of flow must go up
and the only place it has to escape
is that small area left open at the top.
Again, the narrower the channel, the faster the flow,
that's just from a conservation of mass point of view.
So you see a jet jumping out
and under the right circumstances
that can hit you in the face.
It's somewhat related to the Worthington jet,
that's the jet of water you see,
when you drop something into water,
that topic was covered in a, Smarter Everyday, video.
I'll leave a link in the description,
but in short the water rushes into the space
cleared by the pebble and all that momentum
is directed upwards into a jet that touches your bum.
This is all hand-waving speculation, of course,
what I really wanted to do was see what was going on inside,
I wanted to create a transparent version.
My first thought was to cut the thing in half like this,
and then slap some Perspex on there
so you can see what's happening.
Annoyingly all these things are manufactured
in an asymmetrical way,
which makes that cut very difficult,
actually cutting ceramic is really difficult anyway.
So instead this 2D version is laser cut from acrylic.
The drawing for the laser cutter
was based on a tracing of a picture
of the Gluggle Jug and an assumption
about the thickness of the ceramic.
I wanted to make sure I was getting
the internal dimensions right,
especially in this tail section,
because goodness knows what's happening to the thickness
of the ceramic in that region.
And given how hard it is to cut one of these things in half,
I just bought another one and smashed it with a hammer
so that I could inspect the inside.
So this was the drawing for the outer plate,
and this was the drawing for the separator.
You may notice a problem,
and thankfully, Lisa at Quirkshop who did the laser cutting
pointed it out to me.
There's nowhere for the water to get in,
so here's the updated drawing and here's the final product,
let's see what happens.
(jug gurgling)
Well, that's a lot simpler than any of my theories,
it's basically just bubbles moving back and forth
between the two chambers.
Whenever you hear a gloip sound,
it's a bubble moving back or forth.
It's like the glug sound you get
when you pour water from a bottle,
but it's different in a really crucial way.
Look with the bottle air periodically
rushes into the cavity and when it does
it sets up vibrations in the air
and we hear that as a sound,
but compared to the Gluggle Jug,
it's much quieter and that's because the sound
is coming from a closed cavity,
it's somewhat insulated from our ears.
The reason the Gluggle Jug glugs
are so much louder when you bring it up to vertical,
compared to pouring water from a bottle,
is the fact that the bubbles,
that is to say the Gluggle Jug glug bubbles,
are escaping into an open cavity.
The sound that is generated
is able to escape through that open hole at the top
and therefore it's louder in our ears.
That explains why the glugs are more muted
when you're tipping the jug,
it's because the bubbles are traveling the other way
into the closed cavity of the tail.
It's my hypothesis that the pitch of the glug
is the resonating frequency of this pipe
and that's something we can test
because the wavelength of the sound produced by a pipe
that is open at one end and closed at the other,
when it resonates- (pipe humming)
Is four times the height of the pipe.
That's because there's a node here and an antinode here,
so the full wave is like this.
Well, the spectrometer here
says that the frequency of the sound is 480 hertz.
We can get the wavelength by dividing the speed of sound
by the frequency.
I'm gonna say that the speed of sound
is 347 meters per second,
that's because it's about 28 degrees centigrade in here.
So 347 divided by 480 is 0.72 meters,
divide that by four gives us, well, 18 centimeters.
And look, yeah, that's not bad.
So there you go,
the Gluggle Jug. (drink splashing)
This video is sponsored by Private Internet Access,
that's the VPN provider that my tech-savvy friends
keep recommending to me.
So why would you choose Private Internet Access
as your VPN provider?
Actually, why would you use a VPN at all?
A VPN encrypts all the traffic coming from your device
so that it can't be tracked, or blocked,
by your internet service provider,
or your network administrator, or, you know,
depending on where you live, your government.
Look, the situation is not that bad here in the UK,
but even here, there are certain torrent tracking sites
that are blocked.
A VPN also changes your IP address
and in doing so changes where in the world you appear to be,
which means that you can access content
that's blocked by geofencing.
And importantly, private internet access works
with all major streaming services like Netflix,
which can't be said for other VPN providers.
They also provide 24/7 live chat support,
but for me the main reason
to recommend Private Internet Access,
is their transparency.
Their no-law policy has been proven multiple times in court
and their software is open-sourced,
that means anyone can check how their software works.
A single subscription can be used
on 10 devices simultaneously,
which is more than most other providers.
And if you go to my special URL,
privateinternetaccess.com/stevemould,
you can get a three-year subscription
with two months extra free for just $2.08 a month,
that's equivalent to 83% off.
It's risk-free with a 30-day money back guarantee.
The link is in the description,
so check out Private Internet Access today.
I hope you enjoyed this video.
If you did, don't forget to hit subscribe
and the algorithm thinks you'll enjoy this video next.
(upbeat light jazz music)