this is a pee pee boy
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and it's a popular knick knack from
china it's made of susha
a purple clay and it's called pp boy
because when you pour hot water over its
head
it starts to pee
the pee pee boy is what's called a tea
pet
watching
is famous for its teapots made from a
local clay called
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my but the most popular tea pad of all
is the pee pee boy
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because of the way it reacts to hot
water some researchers
believe the pp boy could be the first
thermometer known to mankind
so i wanted to know what is the science
behind it
i called up my friend alex
and we tried to make our own peepee
board using glass speakers and flasks
to see how that hot water reaction works
this is going to be the peepee boy we've
got a big head
okay and a very
small hole in comparison to the head
that's the important thing
alex is going to use this flask to show
how thermodynamics
drives what's happening inside a pp boy
what we're going to do
is we're going to run exactly the same
procedure that we run on a pp boy
now just so you you can see the water
level a bit better
we're going to add some of this lovely
pink food coloring to it
the first step we need to do we need to
get the air inside this very very hot so
that it expands
as we cool it down the air inside will
begin
to contract as it shrinks the pressure
will get lower but the air pressure
outside
stays the same so what's going to happen
is actually
the air outside the air above us will
actually push the water
inside as you can see the water's been
pushed up yeah
now the next step is how you get the
water out
okay so what we're going to do is we're
going to pour some boiling water
back onto the head of the pea people
this will cause the gas inside that is
now shrunk
to expand again and it's going to push
out
all of that water and it's going to pee
something like a pee pee boy probably
because the the hole isn't quite as
small
comparatively we're not going to get a
big jet but you should see
a similar result let's give this a go
there we go how it goes keep going yeah
now you can see it's peeing out
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so interesting the science behind this
the expansion
and then contraction and then expansion
contraction of
air is essentially the same physics
behind a steam engine
it's the expansion that pushes the
piston out and it's a contraction that
pulls the piston in
just like we're pulling water in and
then pushing it back out
it's exactly how a steam engine would
work so steam engine is just like a
really big
exactly so alex do you think this can be
used
as a thermometer as a very crude
thermometer
let's give it a try let's see if the the
water's hot
there he goes definitely hot enough
could it be used as an accurate
thermometer
not without a lot of extra physics and a
lot of extra mathematics so it's just
like a
for fun thing yeah i think for novelty
value
boom cool cheers
so there you go is the peepee boy the
oldest thermometer in the world
probably not but it sure adds a lot of
fun to tea time
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a jump