06x15 - Cliffs, Party Poppers and Wrestling

[bunniefuu]

[Dallas off-screen] This
is the Science of Stupid.

Yes, this is the show where
science and stupidity collide

in a cacophony of chaos.

You'll see backyard experimenters push
themselves and science to the extreme.

Often with painful results.

Then we reveal what went
wrong and why with the help

of such scientific
principles as trajectory.

Circular motion.

And positive feedback.

So, strap yourselves in because
this is the Science of Stupid.

In this show we'll explore

skate boarding's relationship with
angular velocity,

snow's low coefficient
of friction.

[man off-screen] Oh.

[Dallas off-screen] And how confetti
cannons relate to kinetic energy.

But first this.

Whipped by wind.

Battered by waves and weather beaten
over hundreds of thousands of years,

cliffs are formed out of
hardship and it shows.

The world's highest cliff is generally
agreed to be

the Rupal Flank of Nanga
Parbat, Pakistan.

It rises over 2.8
meter above its base.

[woman off-screen] Honey,
get that chin over there!

[Dallas off-screen] Which is almost 50
times higher than this one in Ireland.

[man] Oh my gosh!

[woman off-screen] You've got
to hold it for 5 seconds.

[Dallas off-screen] And one
would imagine 50 times scarier.

But a mistake on even a smaller cliff
could prove to be fatal.

Which is why cliff jumping...

is never recommended.

Some of the most awe-inspiring landscape
on earth are dominated by cliffs

and the science behind them
is pretty impressive too.

A rock cliff is able to
maintain its structure

and shape due to the properties
of the rock that make it up.

A coherent body of rock has rigidity

with very high compressive and sheer
strengths.

However, over time certain environmental
forces can act to wear away at the rock.

Weathering and erosion
by wind, water and ice

can gradually effect even
the most rigid of rock cliffs

and the rock's own weight, or
the weight of something else

can then overcome that strength causing
it to fall and the cliff to retreat.

It's worth noting that cliffs are not
only breathtakingly impressive

but also
potentially

life-takingly deadly, so it's best to
err on the side of caution

and enjoy them from
a safe distance.

Although I don't think this
guy has heeded my advice.

In fact, that is exactly the
opposite of what I just said.

This coastal cliff has been
eroded by waves

to the point of leaving a natural arch.

When the cliff jumper pushes off

he applies a force to the rock with his
feet

on a section that's already
experience significant erosion.

This force is enough to overcome
the remaining sheer strength,

making rocks join the diver on his
descent

and making that cliff retreat
slightly.

Of course, being at
the base of a cliff

can be just as dangerous
as being on the top of one.

[man off-screen] Jesus!

[Dallas off-screen]
See what I mean?

If the action of waves against the edge
of a cliff can erode solid rock,

then that kayaker doesn't have much
chance

and because he can't just flow
like water can.

-[man off-screen] Jesus.
-[Dallas off-screen] That

is going to sting.

Erosion is, for the most part,
a slow and iterative process.

A tiny crack may form in the
rock surface

and water or ice can penetrate
to dissolve or

apply force to widen
and lengthen the crack.

This can leave the top
of cliffs rather uneven.

[laughter]

[Dallas off-screen] If only someone had
told him what a terrible idea that was.

[man 1] Bad idea?

[man 2 off-screen] I think it's time you
start listening you your little brother.

[Dallas off-screen]
Oh, they did.

Because of the iterative
process of erosion,

what starts as a tiny crack
is widened and

lengthened over time
making its surface uneven,

which fortunately gives
it enough friction to stop him

slipping off the edge.

So, that's cliffs, majestic
and best enjoyed.

[screams]

From a safe distance.

This cliff is heavily
undercut into a cave

allowing boats to go through,

information that would
have been useful to know,

before he jumped
and broke his arm.

Still, he got off lightly
so don't try this yourself.

Getting to grips with skis or a
snowboard can be tricky

because snow has a low
coefficient of

friction with most surfaces,

which means you can achieve
considerable velocity

on even a moderate
slope,

which is why I stick
to the nursery runs.

But some people prefer a
bit more of a challenge.

And there are few things
that I can think of that

are more challenging
than a snow half pipe.

These snowboarders are pretty
radical but if you haven't

got a grip on the science
you could end up with...

[man off-screen] Oh.

[Dallas off-screen]
Some bumps and bruises.

And while skiers might like to think
they have the edge, complacency.

[man off-screen] Oh.

[Dallas off-screen]
Can be painful.

This is one pursuit where understanding
the science

can make the difference between your
après-ski being an aperitif

or a trip to the dentist for a new pair
of teeth.

So, I'd encourage any extreme
sports wannabes to watch this.

To launch off a snow half pipe requires
our man to achieve sufficient velocity

to overcome downward gravitational
acceleration for a brief period.

There's a low coefficient of
friction between the snow

and his board helping him
achieve this velocity.

To perform a spin in the air

our man must induce a sufficient
torque on himself to impart

angular velocity but not
too much or too little.

Fortunately, snow is
somewhat compressible

reducing impact
compared to, say,

concrete and
minimizing injuries.

[snowboarder] Oh.

[Dallas] The American superstar
snowboarder

Shaun White achieved a 23
foot jump

from a half pipe in 2010 but
he'd had a lot of practice

and I imagine he also has an
instinctive grasp of physics,

unlike our latest
intake of alpine alumni.

Mike here has always struggled
with science

and he also has a
bit of an overheating problem.

Well, that's fixed
one of the issues.

As he launches off the half pipe
he has enough angular velocity

to rotate a few times in the air

but not enough to land
with his skis flat,

so all that air...
leaves him winded.

Craig on the other hand prefers
to perform fully clothed.

[Craig] Oh.

[Dallas off-screen] Due to
his body position he launched

with a little too much horizontal
velocity,

giving that cameraman an
extreme close up.

Clearly this is a dangerous pursuit

so maybe the most important thing to
remember...

[cameraman off-screen] Oh.

[Dallas off-screen] Is
your health insurance.

[man] [bleep]

[Dallas off-screen] What
scientific principles are these

friendly fishermen
about to witness?

[fisherman] Hey, hey. Hey.

[Dallas off-screen] Have you guessed
what scientific principles

these animated anglers are
about to witness?

[man off-screen] Oh my God!

[Dallas off-screen] If you said
'momentum' then well done you.

The moving boat, like all
objects in motion, has momentum.

This is a function of
its mass and velocity,

and because it's large and moving quite
quickly it has a lot of momentum.

Despite a soaking, our fearless
fishermen

escape with relatively minor
injuries.

One of my favorite things about
having a celebration

is that it gives me an excuse to get the

party poppers out and enjoy the minor
rush of using domestic pyrotechnics.

This science obsessed dad
clearly shares my sensibilities,

but I think he might have got
a little bit carried away.

I'm not convinced that the correct
effort

to reward ratio has been
realized.

[man] Was that it?

Flaming two hours
of work for that!

[Dallas off-screen] Obviously
if you wanna bigger bang

a confetti cannon might
be preferable.

[woman off-screen] I don't think you're
supposed to aim at the light!

[Dallas off-screen]
She's got a point.

Yeah, party poppers and confetti
cannons are a lot of fun

but they're also expl*sive and therefore
potentially dangerous,

especially if you
don't understand the science.

They're powered by small explosions

that release a large amount of energy
and gas,

creating a pressure wave.

This gives the lightweight confetti
kinetic energy

to make it fly through
the air.

Over distance the intensity of
the pressure wave

decreases due
to the inverse square law

and the confetti loses speed
thanks to drag in the air.

And of course, when setting
off a party popper

or confetti cannon it is safest

to direct it away from
yourself and anyone else,

so with that in mind let's put theory
into practice in the real world.

And what better way to
begin than a festive party,

always nice to get new
year started with a bang.

[screams]

[Dallas off-screen] He has his confetti
cannon the wrong way round

so the force of the pressure wave is
directed straight at this body

and at close quarters that
pressure wave and the confetti

carried with it still have
most of their kinetic energy.

[cameraman off-screen] Oh.

[Dallas off-screen] Now, I'm no expert
but I suspect letting off a confetti

cannon whilst riding a hover
board is a bad idea.

But not as bad an idea.

[man] Oh my God!

[Dallas off-screen] As
aiming at someone's face.

Luckily, she's fine.

When the cannon goes
off at point blank range

the confetti's velocity is directed
straight at his friend's face.

And with the confetti moving quite fast
she's knocked off her feet.

[woman off-screen] [Bleep]

[Dallas off-screen] While he
makes a roll for it.

Nice touch, this one is shaped just like
a real bottle of bubbly.

[girl] Ah.

[Dallas off-screen] Yeah, you really
don't want to look down the end.

Now it's time for today's
science lesson,

that part of the show where we
take apart one

specific scientific principle
to see how it works.

So, who can tell me what the
following have in common?

This gym spinner.

This clumsy ring bearer.

And this silly slider.

[man groans]

[Dallas] Did you guess that they were
all to do with angular velocity?

If you did, well done and
feel free to enjoy the warm,

self-satisfying glow of
knowing you were correct.

Angular velocity is the speed
of rotating objects,

linear velocity becomes angular

velocity as they
rotate on the spot.

They can change their angular velocity
by changing their moment of inertia,

how spread out their mass is.

Large moments of inertia mean a
slow spin

but reduce it and you
increase the angular velocity.

Hopefully your heads aren't spinning
after that

because now it is time for a test,

let's see who's been
paying attention.

Question one, what
is angular velocity?

It's the speed that something
spins at

as this careless
chap is about to demonstrate.

[cameraman off-screen] Oh.

[laughter]

[Dallas off-screen] When the juice hits
the fan, angular velocity accelerates it

to nearly 20 miles per hour,

yet another thing
not to try at home.

[cameraman off-screen] Oh.

[Dallas] Question number two, how can
you change your angular velocity?

By changing your moment of inertia but
ideally not like that.

His moment of inertia is too big while
his angular velocity is too small,

meaning he gets a
trip to the dentist.

Okay, now the third
and final question,

how can angular velocity
relate to linear velocity?

This skater is about to find
out in a rather painful way.

Angular velocity in its propellers

is turned into linear velocity of the
drone as a

whole, giving it lift and forward
propulsion but not quickly enough,

to avoid that.

Traction beneath his tire turns its
angular velocity into linear velocity.

[screams]

[laughter]

[Dallas off-screen] But
sadly, not quite enough.

[screams]

[Dallas off-screen]
Class dismissed.

[Dallas] Health and safety around
swimming pools

has always been an
important area

of research for us here at
the Science of Stupid.

So you'll already know the basics

like not to go into any pool if you
can't swim.

But no matter how much work we do, there
is still so much to learn.

Francisco and Albert are exploring the
physics behind the hugging dive.

While Ralph is working on the safest way
to throw Mrs. Ralph

off a pool side
c*ck bar.

[screams]

[Dallas off-screen]
Nice work, Ralph.

[camerawoman off-screen] Okay.

[Dallas off-screen] And little Alice is
discovering it's best to ignore Daddy

when he has a great idea.

[laughs]

[Dallas] Yes, launching oneself
into a swimming pool is fraught

with scientific complications

and these are multiplied when that
launch is assisted by others.

But we are getting ahead.

Let's start with reminding
ourselves about inertia.

The resistance of any physical object to
changes in its state of motion,

that means if something is stopped it
wants to stay stopped.

To jump off his
buddy's shoulders,

Barman needs to overcome
his inertia using force.

From his frame of reference,

he is applying all the force to
accelerate himself upwards

but if his friend does the same
it can boost his launch.

It's important that both he and
his friend

launch in the same
direction or he'll be unprepared

and unable to compensate for
the unexpected direction change.

[screams]

[Dallas off-screen] And two people
pushing together means more force

and more acceleration
than he anticipated.

The great thing about water
is that it should provide

a soft landing by slowing the

deceleration of anything landing in it,
so as my grandmother told me,

always make sure you land in
the pool and, of course,

you should always have the permission of
whomever you're chucking in.

That's safety but it's
also just basic manners.

Alright, so have these
guys been paying attention?

[woman] Woo.

[Dallas off-screen] Nailed it.

[woman off-screen] Can you hold
me and I'll do a backwards flip?

[woman] I like to...

[Dallas off-screen]
What about her friend?

[woman] Go straight cause I'm gonna do a
flip.

-[man] That way?
-[woman] Yeah, I can flip backwards.

[Dallas off-screen] Well,
she certainly seems keen.

of course there's a fine
line between confidence,

and overconfidence.

[woman] That could
have been way worse.

[man] Are you okay?

[Dallas off-screen] From
her frame of reference, all

she needs to do is push
up and lean back.

But with no horizontal
component to the launch

she's propelled
directly upwards,

so when the
momentum runs out

gravity does its thing.

[woman] Oh, that could
have been way worse.

[Dallas off-screen] In theory, more
people should make a launch easier.

[man off-screen] Oh.

[Dallas off-screen] But do
choose those people wisely.

The additional force provided by the
extra hands

becomes a problem when they
fail to

synchronize, and their combined forces
send them into an unexpected direction.

[man off-screen] Oh.

[Dallas off-screen] I won't sugar coat
it, that is gonna hurt in the morning.

Remember, if more than one person is
doing the launching,

synchronization is
essential.

[man off-screen] Three.

[camerawoman off-screen] Oh.

[Dallas off-screen] Perfect.

The well-synchronized launch actually
provides too much force,

meaning he's accelerated
head first into the ceiling.

[camerawoman off-screen] Oh.

[Dallas off-screen] Hopefully that's
knocked some sense into him.

Professional wrestling is very different
from the Olympic sport of wrestling

as it's a type of performance art that
combines athletics with theatrics

but that doesn't mean
people don't get hurt.

They often do, so this is best left to
the professionals trained

in a variety of combat moves,

that are choreographed
to look impressive.

But in reality, damage to
the competitors is limited.

Once the fakery was kept hush, hush but
now it's more of an open secret,

like my... let's not go there.

However, when amateurs get involved the
lines between fake and real

get a bit blurred.

In order to be entertaining
pro-wrestling has developed

impressive moves that tend
to involve big impacts,

so I think we'd all like to know what
are the tricks to limiting the pain

and damage while still
making it look awesome.

Professional wrestling involves
a lot of impact force generated

when something with momentum
is rapidly decelerated.

Pressure equals force divided by
area,

so the pain and damage can
be lessened by decreasing the

local pressure by spreading the
force out over a large area.

There are loads of professional
wrestling moves

all with very exciting
names.

There's the power slam, the
Boston crab, the doomsday device

and my personal favorite,
the neck breaker.

But before we get carried away,

it's probably a good idea to get some
practice in.

Maybe we should
take things outside.

[cameraman off-screen] Ah.

[Dallas] Yeah, I don't think his parents
will be pleased with that.

When he lands on his back he plans to
distribute his impact force,

but his foot has quite a lot of momentum
and he's able to deliver a large force.

[cameraman off-screen] Ah.

[Dallas off-screen]
Over a small area.

Of course, the best place
for wrestling is in the ring.

That was both painful and embarrassing
but at least the crowd is having fun.

When he fumbles his legs over the rope

he doesn't get the reaction force he
needs so he

doesn't generate enough angular
momentum

to go all the way round and
gets a...

-[cameraman off-screen] Ah.
-[Dallas] Face full of canvas.

Perhaps he should have left
it to the professionals.

Much better.

Well, that's all we have time
for for now,

but I will leave
you with one final thought.

If someone tells you that you
are one in a million,

they're actually telling you that there

are over 7,000 people just
like you

but hopefully none
of them are these guys.

[music plays through credits].