Kind: captions
Language: en
a couple of years ago my friend Destin
and I wanted to definitively answer the
question does water actually swirl the
opposite direction down the drain in the
other hemisphere at the time I was
living in Sydney Australia and dtin was
in Huntsville Alabama those are about
the same latitude just opposite sides of
the Equator so we created two videos
that were meant to be watched
simultaneously and if you want to
synchronize them yourself you can click
the link in the description but we also
recognized that that was a hassle for
some people particularly watching on
mobile devices and that's why I'm now
releasing this extra wide video of both
videos
synchronized The Simpsons did a whole
episode based on toilets flushing the
opposite direction in Australia plus
other shows have supposedly demonstrated
this effect so I have seen documentaries
that seem to indicate that which
hemisphere you're in determines which
way the water is going to swirl but
there's this other group of people and
they seem really confident that it
doesn't matter where you're at the
water's going to swirl however it wants
so is this a real effect or not the
application of the principle to draining
water in Earth's two hemispheres is just
bunk but if you ever just look for
yourself and figured out which way your
toilet swirls if you try it yourself
you'll find inconsistent
results here in Alabama I've noticed
that some turn counterclockwise and some
go clockwise this sink sometimes drains
one way and sometimes the other way you
see most toilets have little jets in it
so the swirl direction is determined by
the design of the toilet and not which
hemisphere you're in in any container of
water there's always going to be some
rotation the water is not perfectly
still and it is this rather than the
hemisphere that determines which way the
water will swirl down the drain so it's
a myth crossing the Equator does not
mean the toilet's going to change
directions but what if we come into the
garage and do a more controlled
experiment but what if we could
eliminate all motion from the water this
is a 1 and 1/2 M Kitty pool I have here
a 5T wide Kitty pool instead of filling
the pool with no vorticity at all I'm
going against the way it's supposed to
drain so I'm trying to fill it with the
flow going clockwise I actually filled
the pool in the anticlockwise direction
to be sure that any clockwise motion we
see is not due to the way I fill the
pool so let's let the water settle for a
complete day so that we know that it's
perfectly still and I've left this water
sitting here for 24 hours so it seems
like I've damped all of the Motions from
The Filling well I'm not going to reach
in and pull a plug out because that
would induce some vorticity I'm going to
use this valve that I have connected to
the bottom of the pool I really hope
this works Destin wish me luck good luck
there I'm about to pull the plug okay
opening the valve in 3 2
1 water should be flowing and the pool
is draining but you can't see any motion
of the water just yet okay water's been
flowing for a couple of minutes and I
haven't seen anything yet so we're going
to put some dye in it to help us see
where the water is Flowing I'm going to
put some food coloring in on the four
cardinal directions around the
pool check it out it's like a tornado
like right off the bat we got a
counterclockwise rotation we filled it
up clockwise and now it's going
counterclockwise you can clearly see
that the water is Flowing clockwise in
this direction and that makes sense
because that's how it should flow in the
southern hemisphere due to the Earth's
rotation we have a kitty in my garage
and the whole Earth is
rotating and the water's going
counterclockwise because I'm in the
northern hemisphere it's real this is
real but you can see what a tiny little
effect it is and what extraordinary
lengths I had to go to to see this
effect so really you're not going to see
it in a bathtub and you're not going to
see it in a sink or in a toilet because
there are other sources of angular
momentum that totally wash out this
effect we just proved it because we just
eliminated variables the cor effect is
real have it it
works to understand how it works imagine
a pool with one Edge touching the South
Pole think about a pool near the North
Pole the pool is stationary relative to
Earth but every day it's actually
completing one full Revolution the Earth
is spinning on its axis so the pool
spins around the pole once a day now you
can see the side of the pool furthest
from the pole travels much farther every
day than the side right next to the pole
the whole pool is moving but the part
that's closest to the equator has has
more momentum and the part that's
closest to the pole has less so the
outer side of the pool is moving fastest
towards the east and as you get closer
to the pole the velocity decreases down
to zero think about these velocities
relative to the drain in the middle now
imagine we drain the pool when we pull
the plug all the water starts moving
towards the middle water From The Far
Side is moving too fast relative to the
drain and so it gets out ahead whereas
water from near the pole is going too
slow and so it lags behind the side
nearest the equator is going faster so
that water outruns the drain but the
water nearest the pole is going slower
so it falls behind so when the water
approaches the drain it swirls
counterclockwise this is the reason
hurricanes swirl counterclockwise in the
Northern Hemisphere and this is the
reason Cyclones swirl clockwise in the
southern hemisphere the center of the
hurricane has lower pressure just like a
drain so the hurricane swirls just like
our pool
the higher pressure air rushes into the
eye of the storm and just like in our
pool swirls in the direction dictated by
the hemisphere and that's the truth
about toilet
swirl hey I hope you enjoyed that and uh
thanks for watching if you haven't
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Channel yet then click here or if you
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