okay everybody today we're going to be
seeing if things sink or float when
they're in a vortex and a vacuum chamber
now this is a really interesting
question let me explain what I mean so I
have here a ping-pong ball and you see
that it floats in water pretty easily
but now watch what happens when I turn
this stirrer on and start stirring the
water oh there it goes it's getting
sucked down to the bottom of the water
so for some reason when I start stirring
the water the ball gets sucked down it
stays there it's sucked to the bottom of
the container so why is this happening
why is it that the ball gets sucked down
to the bottom when the water starts
moving and then you can see when I turn
off the spinner it pops back up so as
soon as I stop the water spinning very
fast the ball floats back up so this is
actually really interesting and the
reason it's happening is because
whenever a fluid moves fast the pressure
automatically lowers so let me show you
what I mean so say I want to suck some
water up from this straw but I don't
want to touch the straw I can still suck
water up by just blowing air over the
top of it so I've taped my straw on the
end here and now I'm just gonna blow
over it
so you can see it just spraying water
out of the top and that's happening just
because I'm blowing air over the top of
it and the pressure is lower so it's
essentially getting sucked up the straw
without even touching the straw you can
see a little bit clearer when I use a
clear straw so you can see the water be
drawn up it so you can see when I blow
how the water rises up so now that we
understand that moving fluids cause
lower pressure now we can start to
understand why this ball would sink so
as the spinner starts to spin it drags
water around with it and since that
water is moving fast it now has lower
pressure and the water at the center is
moving faster than the water on the
edges and so that means the water at the
center has lower pressure and so that
means that it has lower pressure than
even the atmosphere above it and so the
atmosphere starts to push down into it
you can see the atmosphere started to
push the air down until it hits the
bottom and so that push of air down is
happening because the water actually has
lower pressure than the air above it and
so when you stick a ball on it there's
lower pressure in the center of the
vortex and so the ball now gets sucked
down but here's the interesting part
I told you that the reason the ball is
getting sucked down is because the water
is moving and so it has lower pressure
and the only reason it causes the ball
to go downwards because the atmosphere
above it has higher pressure than the
water now so that got me thinking is it
really the atmosphere that's pushing the
ball down or is just the movement of the
water dragging it down well if I
understand the sucking motion of
vortices then to me it just means that
the reason that they suck things in is
because the water is moving faster and
so they have a lower pressure than the
atmosphere so if we took away the
atmosphere that would mean there's no
sucking motion so today I'm going to
stick this in the vacuum chamber and see
if when we create a vortex that the ball
stops getting sucked down because
there's no atmosphere to push it down so
let's see if that happens in the vacuum
chamber well the ball sink our float in
a vortex in the vacuum chamber okay
let's put our ping pong ball on start
the vortex
you can see it starts to sink now now
let's create a vacuum in there and see
what happens okay three two one
okay we're at 0.7 atmospheres point six
out miss fears
okay we're at point three atmospheres
now I don't know it's still sunken down
there
Oh point two atmospheres we're getting a
lot of dissolved bubbles coming out of
there now
a lot of the dissolved air is coming out
of the water
Oh interesting is starting to come up no
way we're at point one atmospheres and
it's not sinking anymore I'm starting to
flow up so you can see this air pocket
below it's starting to kind of push it
up no way so I only guess this would
happen I had no idea if it would really
work but it looks like it really worked
it's not sinking in a vacuum that's so
weird
so basically it's not sinking down
because even though the water is moving
really fast there's barely any
atmosphere there to push the ball down
okay now I'm gonna lift the air back in
and see if it sinks back down three two
one
[Music]
so as soon as I let the air back in it
starts to push the ball back down that's
so cool
now at full pressure again it's
completely submerged okay so this is a
really cool effect basically even though
you have really fast-moving water in the
center of the vortex and that
fast-moving water is creating low
pressure it doesn't really matter
because the atmosphere around it in the
vacuum is also low-pressure and so
there's not this force pushing it down
like there is an atmosphere so another
cool test would be does that mean that
in a high-pressure chamber a vortex has
even more sucking motion I don't have a
way to set that up right now but that
would be a cool experiment to try and
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