05x18 - Moped Wheelies, Splashless Dives and Kettlebells

[bunniefuu]

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

Yes, this is the show where
absurdity and acumen face off

dressed in lab coats.

Prepare yourself to see
renegade risk takers,

gamble it all in the pursuit
of scientific knowledge.

We'll show what went wrong.

And why.

With the help of fundamental
concepts of science such as

co-efficient de-friction.

[screams]

Torque.

And Newton's third law.

[grunts]

In the w*r between
science and stupidity,

you have to choose sides.

So, don't be a loser.

Pay attention, it's
the Science of Stupid.

In this show, we'll
be looking at sliding.

Nucleation.

[laughs]

And deflection.

[grunts]

But first, this.

For most of us, ice skating
brings up the image of

leotard-clad dancers, spinning
to classical music and

interpreting ideas of romance.

But not me, I'm all about the hard core
winter sport Crashed Ice.

[Dallas off-screen] Crashed
Ice involves ice skating

downhill at high speed with
tight turns and steep drops.

To succeed, you must
practice with the pros.

And don't let anyone
get in your way.

[grunts]

Three hip replacements later
and I realized what it was

that I was missing.

The science.

[Dallas off-screen] Our man
can easily gain velocity down

an ice slide, thanks to the
low co-efficient of friction

between his blades
and the ice.

The skate forms a small
groove in the ice as it moves,

which resists sideways motion.

If his skates slip
backwards or forwards,

slip sideways out from the
groove or dig in too far,

he'll lose stability.

I haven't come out of
the groove since 1978,

but enough about
my disco days,

let's strap on our skates and get ready
for competition time.

[Dallas off-screen]
On your marks, get set.

I'm not sure he's
getting a medal.

The low co-efficient to
friction between ice and blade

gives high velocity but not
much grip when the skate

leaves the groove.

His right leg slides out
creating a lack of stability

and gravity drags him down

for a crash landing.

Can anyone else do better?

[man off-screen] Ow.

[Dallas off-screen]
Well, not him.

I think the idea is to
go down on your feet.

Right, let's try
some cornering.

[grunts]

Eh, that didn't go
as well as I'd hoped.

On the downhill, he has
sufficient grip by creating a

groove for the skates.

While cornering, his skate
slips out of the groove.

The co-efficient to friction
is too low to offset the

centrifugal force.

[grunts]

If you get up you
can still win.

You're gonna have to go
faster than that though.

Yeah, loser.

To be a true Crashed
Ice champion,

skaters must be
able to jump but,

with a low co-efficient
to friction,

any legs positioned forward
of the skater's center of mass

will be likely to
slip from under them,

which is not what you want
on a steep downhill race.

Trust me.

[Dallas off-screen]
There you go.

That is how it's done.

That was more of a long jump.

With his legs forward
of his center of mass,

gravity rotates him to the
ground and his crashed ice

becomes a crashed backside.

We might need to
practice without the ice.

I give up!

For most people, bouncing on
a trampoline is enough of

an adrenaline rush.

But not for me, I love to push
the envelope a little and make

things difficult, so I
always try the drop-in.

[Dallas off-screen]
Lovely stuff.

[grunts]

Yeah, that's less good.

Even if you have mastered it, best not
to try it from a roof.

[man] What are
you trying to do?

[Dallas off-screen] I don't
know if anyone knows the

answer to that!

Clearly, this is a dangerous
pursuit that should not be

attempted without
caution, preparation and,

if you're young,
adult supervision.

But what separates those that
re-bound with those that are

simply floor bound?

[Dallas off-screen] The high
platform means the jumper

builds lots of kinetic
energy as he falls.

By landing in the center, our
man can make the best use of

the elastic recoil
of the trampoline,

converting his kinetic energy
to elastic potential energy

and back again to return
him to the platform.

But if his landing
isn't vertical enough,

he'll have too much horizontal
displacement on the bounce,

which will send him flying.

So there's an energy build-up
that must be converted.

Get the angle right and you're
safely back to the platform or

heading straight upwards.

Get it wrong and you
could be off anywhere.

Sounds tricky.

I wonder if people have
been paying attention?

[Dallas off-screen] Warning,
stripey socks will not reduce

the risks.

As he has just discovered.

By landing slightly later, he
gets an extra kick of kinetic

energy and an off vertical landing means
it sends him straight

out of the net.

Let's see if this
grown-up does any better.

If anything that's worse.

The high start gives him
lots of kinetic energy,

but when he leans forward on
the bounce he doesn't develop

much vertical displacement
and his horizontal

displacement takes him...

[man] Whoa.

[Dallas off-screen] For a
little lie down on the grass.

Shall we step things up?

[man] I'm good!

[Dallas off-screen]
Maybe stick to the basics.

An impressive rotation but
he doesn't quite complete it,

leaving his feet in
the wrong position.

He needs a bit more horizontal
displacement to make it safely

back onto the platform.

Hindsight is a
wonderful thing.

Oh, and one last tip,
make sure you hit,

the trampoline.

We all love a pleasure flight;
there's so much to see.

But can you guess which
principle this high flying

holiday maker is about
to unexpectedly prove?

[Dallas off-screen] We asked you what
science

this high flying photographer
was about to show us.

[man] Oh, no.

[Dallas off-screen] Did you
say Bernoulli's principle?

Of course you did.

Because the air outside the
plane is rushing passed the

window much faster than
the air inside the plane,

it follows from Bernoulli's
principle that there must be a

decrease in pressure as you
move from inside to outside,

causing suction on his camera and a sad
tale of lost memories.

Much to the relief
of his friends.

At school I went everywhere
on my skateboard.

I loved how it helped
me combine coordination,

balance and looking cool.

I even came up
with my own moves.

[Dallas off-screen] There
was the backstreet slalom.

[grunts]

The barrier star jump.

[grunts]

Even synchronized skating.

[man] Three, two, one.

[Dallas off-screen] Yeah, that
one needed a bit more work.

But the one thing I
never managed to perfect was

the nose slide.

It's probably because I never
bothered with the science.

[Dallas off-screen] Pushing
down on the rear of the board

creates a reaction force to
propel it off the ground.

He then uses his feet to
generate angular momentum,

twisting the board in order to
place the front of the deck

on the block.

Keeping his weight directly
over the front of the board,

kinetic friction is just low
enough to allow the board to

slide so he can go the distance without
losing control.

I might have failed
to perfect this move,

but that doesn't stop me wanting to see
others get it right.

So, one word of warning when
you try anything like this,

helmets and pads are as
important as board and ramp.

[Dallas off-screen] A skater
and his board inseparable

and as one.

[grunts]

Well two.

He fails to rotate the board
the full 90 degrees needed to

be perpendicular to the wall.

And landing sideways means
that the rider and the board

sadly part company.

[grunts]

He looks professional.

I spoke too soon.

His wheels can't roll sideways and are
much grippier than the board.

So he never achieves a slide.

Someone must be
able to nail this.

[grunts]

Just not him.

He lands with his center
of mass too far forwards,

so kinetic friction isn't
high enough to stop the board

sliding out from under him.

[grunts]

Anyone want a final go?

Right.

I'm calling this to an end before
someone gets seriously hurt!

It's time to sit up, face the front and
start paying attention.

If you do, you might
just learn something.

Yes, it's the science lesson.

That part of the show where
we get to the heart of a

scientific idea and today's
principle is united by the

following three things.

[Dallas off-screen]
This party popper.

This barking bike rider.

And this gushing geyser.

If you said all of these
contained examples of

nucleation, then give
yourself a pat on the back.

As any scientist knows,
nucleation is the point at

which a substance starts to
change such as going from a

gas to a liquid or self-organizing into
a crystal structure.

So, pens at the ready,
as we see it in action.

[Dallas off-screen] When a
strawberry is dropped into

sparkling wine, the shock
is enough to make bubbles of

carbon dioxide rapidly
nucleate and grow.

Submerged in the liquid,
the strawberry's rough skin

provides lots of surface area
for nucleation to continue.

When an ice cube is dropped
into distilled water chilled

below freezing point, it too provides a
surface for nucleation.

So ice crystals
instantly form and grow.

Okay. I hope you're all paying attention
because it's quiz time.

Question one.

When can ice be soft?

[Dallas off-screen] The joy
of biking downhill is you just

get on and let gravity
do most of the work.

The key is, of
course, knowing.

[grunts]

How to stop.

He's fine and the reason
why is our answer.

The nucleation of ice crystals in this
case has created snowflakes.

It might offer
little friction,

but individual delicate
crystals trap air and are

perfect, for an injury free
if undignified crash landing.

[man] [Bleep].

[Dallas off-screen] Meaning
you can land almost anywhere.

[man] [Bleep], [bleep].

[Dallas off-screen]
Apart from there!

Question two.

How can you make bubbles of
gas nucleate from a liquid?

[Dallas off-screen] Great,
it's time for a toast.

What are we celebrating?

[woman] Here's to the New Year.

[Dallas off-screen] Maybe it'll be
filled with good fortune.

[group off-screen] Five,
four, three, two, one.

[screams]

[Dallas off-screen] Ah, there's
always next year I suppose.

At least you
provided our answer.

By agitating it.

Multiple hits ups the
nucleation of the carbon

dioxide dissolved
in the liquid.

This increase the pressure
inside the bottle and,

once it's smashed open,
the bubbles rise quickly.

[screams]

Still, Happy New Year.

If you want to stay dry, hold
the bottle still to reduce the

chances of nucleation.

Just remember to...

Watch your aim.

[man off-screen] Yes.

[Dallas] Time for our
third and final question.

How can you speed up the
process of nucleation?

[Dallas off-screen] This
foolish fellow and his boiling

water are about to find out.

[Drew] Ooh.

[woman] Oh Drew! Are you kidding?

[Dallas off-screen] No,
he really is that stupid.

[woman off-screen] No!

[Dallas off-screen] There's
a large temperature gradient

between the cold air
and that hot water.

But water can't evaporate
easily into cold air,

so any vapor instantly
nucleates into a cloud

of water droplets.

[Drew] Oh.

[woman] Oh Drew! Are you kidding?

[Dallas off-screen] And
that, ladies and gentlemen,

concludes our lesson
on nucleation.

Class dismissed.

[Dallas] There are those who prefer
animals over other humans,

and I can see their point.

Rabbits, for example, never
seem to judge me on my hair,

my political opinions or
if I've showered recently.

They only care if I've got
a pocketful of carrots

and I always do.

[Dallas off-screen]
Animals are great.

Such grace.

Such poise.

Such a clean floor.

Like everything else
in the universe,

animals are subject to
the laws of physics.

So many of them can slide
around like the best of us.

To understand why we have
to look at the science.

[Dallas off-screen] Sliding
is resisted by kinetic

friction, which is
affected by two variables.

The co-efficient of friction
between the two surfaces and

the normal force pushing
the surfaces together,

which is determined by the
object's weight and is reduced

by a steep angle of incline.

Kinetic friction is usually
less than static friction,

so it's harder to start sliding than
it is to keep going.

My best slides were
done on the dance floor,

until I was banned from the
disco for knocking over the

girl I wanted to impress.

At the time, I thought the bouncers were
just jealous of my moves,

but I know realize that they were
appalled at my physics.

[man] Do the moonwalk!

[Dallas off-screen]
Plus there are always

better dancers around.

[man] Oh, my.

Oh look!

[Dallas off-screen] Hang on,
he's definitely stolen

some of my moves.

[man off-screen] I just
got that on record.

[Dallas off-screen] Dog hair
and flat carpet would normally

have two higher co-efficient
to friction to allow sliding,

but the dog produces a
horizontal force by pushing.

This overcomes the static friction and
he's well on his way.

[man] Oh my.

Oh look!

[Dallas off-screen]
To a Jackson 5 slide.

Animals like seals often
use sliding to enter water.

But when the static
friction is too high,

they have to
resort to rolling.

It's exactly the same way
I got down the stairs

after a large meal.

Just as effective, but can
leave you a little dizzy.

It's always important to take your time
getting into a cold bath.

It might be worth checking the
temperature first, next time.

The smooth claws on a
smooth surface create a low

co-efficient to friction so
the cat slides down easily.

The same combination and steep
angle of incline help and

prove that what goes down
won't necessarily get back up.

And he turns that lizard
bath into a Jacuzzi.

When I get time to relax,
I love to play pool with my

friends, but it can be tough
to find people skilled enough

for a proper game.

[Dallas off-screen] I
guess it's my shot now?

We're gonna be here
all night like this.

[grunts]

Well that's one way
to beat your opponent.

When I play, I always like
to throw in a trick shot.

It might not help me win, but
it does surprise my friends

who are then desperate
to know the science.

[Dallas off-screen] The pool
cue delivers a force which

drives the ball
diagonally forwards.

By using a steep cue angle,
the player generates back spin

and it deflects backwards
to pot the hidden ball.

For his next trick, he pushes
the cue ball into the table

generating a reaction
force to make it bounce.

And rebound off the cushion
at an angle back towards him.

So it's all about the power and the
precision of your shot.

Get it right and your friends
will think you're a hero.

Get it wrong and, well,
let's have a look.

[man] Ready?

[Dallas off-screen] Ah, the
classic sinking two ba*ls

in at once trick.

And here's my tip.

[man] Ooh.

[Dallas off-screen]
Don't stand there!

By striking a coin
placed on the bays,

he creates a chip which
lifts it off the table.

It's an unconventional move.

[man] Ooh.

[Dallas off-screen] But
he did pocket both ba*ls.

It's always good to
record your achievements.

And if you fail, you can
just destroy the camera.

The high angle of his cue
gives the ball the jump it

needs to clear
the line of ba*ls,

but the trajectory isn't quite
right, and he misses the ball.

But does hit the camera.

So, that's the secret
to playing pool.

Remember the science and you
too will soon be celebrating.

Smashing stuff.

Well that's quite enough of
this gruesome glimpse into

scientific ignorance, and
unless you want an evening

with the doctor, just remember
the words of Aldous Huxley.

Facts don't cease to exist
because they are ignored.

And if you don't
believe him, watch this!

[music plays through credits].