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are you like me do you like watching
fruit explode and also enjoy physics
well if so there's probably only one
place in the world where those two great
tastes come together in conjunction
America's annual contest to see whose
homemade machine can hurl a pumpkin the
farthest every November thousands of
amateur engineers equal parts da Vinci
and Gallagher converge on a farm in
Delaware to put their contraptions to
the test they compete in divisions based
on what kind of machine they've built
and whoever's device hurls their squash
the farthest wins the only roll no
explosives yeah I know little bit
disappointing there but never
underestimate physics when it's awesome
powers are unleashed it can make even a
seemingly simple machine cause a lot of
squash damage and look good doing it the
machines at the Punkin Chunkin Festival
rely on the release of stored energy to
get the pumpkin airborne this energy
comes from some external force that's
exerted on a part of the machine where
it's been pent up as potential energy
for example there are the air cannons
which release all at once the potential
energy of gas had slowly been
pressurized inside a container and then
there's what the contest calls
centrifugal machines where a motor spins
the pumpkin around the tether which is
pretty cool even though centrifugal
force is not a thing but for where I
stand the most delightful Punkin Chunkin
physics are found in the class of
machines that you probably know as
catapults yes they're not just for
smashing castles or a pole ting cats are
actually many different kinds of
catapults including the manga Nels
trebuchet x' and torsion machines each
using a slightly different sort of force
to create the potential energy when you
think of a catapult what you're probably
seeing in your head is a manga Nell its
main feature is a long beam with a
bucket on one end and the other fastened
to an axle the bucket into the beam is
usually attached to a sling by the
machines main frame then it's pulled
down to apply the force of tension this
tension is what stores up the machines
potential energy until it's released the
punkin chunker though catapults can use
Springs cords rubber or dead weights to
apply tension but they've added an extra
touch of genius to their traditional
manga Nell instead of just a bucket on
the end what it has is a sling what's
the genius in that well it gives the
machine a second fulcrum or pivot point
the first fulcrum being where the beam
meets the axle but when that's released
it throws up the sling which
implies the power of the first fulcrum
this is all very similar to how
trebuchet z' work but they're a little
more sophisticated you know as far as
catapults go rather than holding all the
potential energy at the tip of the beam
where the pumpkin is trebuchet is rely
on a counterweight at the other end
again the beam is pulled down to set the
device but instead of tension being the
force at work here it's simply gravity
the heavier your counterweight is and
the higher you lift it the more force
you get out when it falls as a result
trebuchet tsar much more efficient they
tend to shoot a lot farther and are more
accurate giving you more chunk for your
buck finally you have with the hardcore
chunker's called portion machines most
of these kinds of catapults are hybrids
over the first two they have a sling at
the pumpkin end just like a trebuchet
but instead of gravity they use the
force of tension like a manga now unlike
with a manga now though the tension is
applied to this machine by twisting a
length of rope around the bottom of the
beam and if the same idea is twisting
the river band on a propeller toy
airplane the twisting or torsion is just
tension applied in a rotating direction
instead of straight up and down and we
all know what happens from there
but please don't try this at home unless
you have a scale model or something just
watch from the safety of your sofa
don't miss Punkin Chunkin this
Thanksgiving November 22nd at 8 p.m.
only on science Channel and for more
pumpkin carnage check out Science
Channel comm slash chunk 4 video from
this year's Punkin Chunkin and
high-speed footage of various foodstuffs
getting the crap lone out of them and of
course Happy Thanksgiving
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