04x02 - Swimming Pool Handstands

[bunniefuu]

[Dallas] This is the Science of Stupid.

[reading]

Yes, this is the show
where complex science

collides with complete stupidity.

You'll see backyard experimenters

push themselves and science
to the extreme,

often with painful results.

[screams]

We'll reveal what went wrong and why

using scientific principles such as

vertical acceleration...

[screaming]

...the coefficient of friction

and turning force.

So strap in...

[cat yowls]

...hold on tight,

because this is the Science of Stupid.

[electricity crackling]

In this show, we'll be exploring

angular velocity,

stealth...

[yowls]

...and traction.

Or lack of.

But first this...

[electricity crackling]

I'll always remember the day
I got my first skateboard.

The excitement of being able
to get gnarly with my homies.

Of course, they didn't
want to skate with me,

after they found out
I was calling them my homies.

But still, I'll never forget
how exciting it was

when I first started
learning radical tricks.

[upbeat music]

Ah, that brings back memories.

-[boy] Ahh!
-[Dallas] As does that.

And this was always happening to me.

And that grip tape
leaves a really nasty mark.

Of course the basis of almost
every skateboarding trick

is the ollie.

That's what us skaters call a jump.

But combining speed,
force and timing isn't easy,

and our friend science can explain why.

As he kicks down, our skater rotates

the back of the board
around the rear wheels

and pushes it to the ground,

generating a reaction force
to launch it into the air.

Once airborne, he rotates his foot

and flexes his knees and hips
so the board gains height

and then controls the front of the board

so it follows the shape of the arc

it makes through the air,
before pushing the back down

so the board is level when he lands,
evenly distributing the impact force

across all four wheels.

Well, that all sounds
fairly straightforward,

but before you start jumping
over things on your board,

you need to gain sufficient speed.

A run-up is very important
for building horizontal momentum.

[man] You win this
and you win a million dollars.

[Dallas] As is a financial incentive.

But a good launch is vital.

This guy's center of mass
was too far forward

when he hit the ramp,

so he couldn't propel himself effectively

and his front wheels
weren't able to lift onto it.

He still got air, just without his board.

[boy] I think you missed the target.

[Dallas] I think you're right.

Let's see how he does.

I guess that's why
it's called a roadblock.

This skater didn't push
hard enough on takeoff,

so didn't get enough reaction force,

which means...

not enough height.

And height is a key ingredient

if you want to jump over things.

Rubbish.

This backyard skater
doesn't push hard enough

to produce the reaction force required,

but with the ramp so close to the bin,

he didn't really have a chance anyway.

Nice kick flip.

Good landing.

-[boy] Yeah!
-[Dallas] Painful dismount.

After a textbook ollie,

this guy shows us
why a solid place to land...

is vital to a successful jump.

As is...

landing with your skateboard
the right way up.

Adding a trick into the mix,

he spins his board an extra


Well, it's not the kind
of landing he'd have wanted,

but it's--it's a landing.

So there you go, skateboard ollies.

-[boy] Ahh!
-[laughter]

[Dallas] Not really worth it.

[electricity crackling]

I love jumping,

and I love kicking.

They're both fantastic ways
to spend an afternoon.

But I've always wondered
if there was a way

to combine my two hobbies.

Well, it turns out there is.

[upbeat music]

[man] Got it. Ohhh!

[Dallas] Just not quite like that.

Ah, a military man.

Highly trained...

in unarmed combat.

But what if I'm more formally dressed?

[laughter]

Grass stains are a nightmare
to get out of chinos.

Yes, a flash kick
is all sorts of fantastic.

It's a back flip with a kick added in.

And just like mac and cheese,
burger and fries,

or wine and regret,
they just seem to go together.

So let's find out how this
two-in-one is done.

As our man jumps upwards,
he generates vertical momentum

and then converts some of it
into angular momentum,

as he leans back
and kicks his legs around.

By flexing his hips and tucking in,

he decreases his moment of inertia,

making it easier to rotate,

increasing his angular velocity.

Then for the kick,
he extends his leg at the knee.

His outstretched foot will travel faster

than the rest of his body.

So it's jump, turn, tuck, kick, land.

Got it? Good.

Right, let's see if this lot have.

First box to tick is a back flip.

[boy] Aye-yi-yi.

[Dallas]
I think you need a bit more commitment.

As this guy didn't lean back enough,

he couldn't generate
sufficient angular momentum,

so he seriously under-rotated.

[boy] Aye-yi-yi.

[Dallas]
I couldn't have put it better myself.

Done right, a flip can lead you
on to bigger and better tricks.

Nice spin.

-[boy 1] Ahh!
-[boy 2] What?

[Dallas] Terrible landing.

Our kicker added a twist to his flip

for some added flair,

but he should have concentrated
on one of the basics,

like getting enough height
for a full rotation.

-[boy 1] Ahh!
-[boy 2] What?

[Dallas] I said he didn't
get enough height for--

oh, forget it.

Get a big push
from a friend and you get...

a detention.

With the help of his chum,

this schoolboy increased his
height and angular momentum,

but it didn't really matter,

as his spin was interrupted.

A dance-off in a fox costume,

this could only be
made better by one thing.

[crowd oohs]

And that wasn't it.

Using the pillar to launch into the flip

might have increased his angular momentum,

but his foot slipped,

and he didn't generate
enough reaction force.

I guess foxes aren't
as agile as they look.

But boy, do they have some stylish moves?

[electricity crackling]

Can you guess what science
these high flyers

are about to show us?

[electricity crackling]

[Dallas] Did you work out the science

these backyard experimenters

are about to demonstrate?

Yes, it's bending force.

As they swing in sync,

they're exerting a considerable
bending force on the wood,

and because their swing changes
the direction of the force,

the wood is also under twisting

or torsional stress, resulting in a snap.

And an awkward conversation with Mom.

[electricity crackling]

Most people think that walking
is just a simple case

of putting one foot in front of the other,

which it is, but it can still be tricky.

There's trips...

slips...

-[screams]
-[woman] Oh, my God.

[Dallas] ...and a lack of grips.

-[woman] Ah!
-[laughter]

[Dallas]
Congratulations on graduating though.

While your average two-year-old

has mastered the basics of walking,

throw in a long robe
or dress into the equation,

and things can get tricky.

But what is the science involved
in keeping you vertical?

Because wearing a robe will restrict

the length of stride
our graduate can take,

he needs to reduce
how far he stretches his legs

and take shorter, quicker steps.

This will help him keep his feet
under his center of mass

as his momentum carries him forwards.

He also needs to take care

that he doesn't step
on the edge of his robe,

as this can exert a downward
pulling force on him

and reduce friction
between his foot and the ground,

making him slip.

And don't get me started with stairs.

If you're wearing a dress,
they're even trickier,

as you often need to stretch
your legs further, apparently.

Anyway, who knew walking
could be so complicated?

[cheering]

This guy looks rather confident.

Perhaps too confident.

Hmm, what was it that comes after pride?

Oh, yeah, that.

Our attention-seeking graduate

didn't reduce his stride to compensate

for the restrictive robe
and was unable to flex

far enough at the hip
when starting down the stairs.

So maybe it's stride
that comes before a fall.

The catwalk model is basically

a professional at walking,
so this should be good.

But it isn't.

Her poor foot placement
created a downwards pulling force

and reduced the friction
between foot and runway.

Which led to a foot slip

and a less than elegant catwalk crash.

Ah, another freshly plucked graduate.

All those years of study,
all those tuition fees and...

still he hasn't mastered
the walk down stairs.

But what he lacks in coordination,

he more than makes up for
in upper body strength.

[laughter and cheering]

[school bell dings]

[crash]

[liquid bubbling]

Who threw that?

Jones, stay behind after class.

Yes, it's time for today's science lesson.

It's that part of the show
where we use the scalpel of physics

to dissect one specific
scientific principle.

Right, who can tell me
what these three things

have in common?

These girls...

having a ball.

This toddler's high hair.

And this guy with a magnetic personality.

Really? Magnetic?

I think we're being conned.

Yes, things like gravity,
static electricity

and magnetism are all non-contact forces,

meaning they're forces
that can affect an object

without touching them.

Let's let science explain more.

This is a Van de Graaff generator.

It generates static charge by causing
a buildup of electrons on its surface,

which move into his hair.

Because like charges repel each other,

the individual hairs
feel a repulsive force

and move away from each other.

When we put these pie cases on top,

they too become negatively charged

and are repelled from the sphere
one by one.

The cases are then subject
to another non-contact force...

gravity.

So that's the science.

Let's see who's been paying attention.

Question one.

What's an example of a non-contact force

that's only able to attract objects?

You know what's really
good for team building?

Trust exercises.

[woman] Ahh!

[Dallas] But that only works
if you can trust your coworkers.

[woman] Ahh!

This lady fell victim
to the non-contact force

of gravity.

Since her former friend got distracted,

she wasn't able to catch her,

and because gravity
is an attractive force,

it pulled her down to the ground.

How will she ever trust again?

Right, question two.

Name an example of a phenomenon

that's capable of exerting
a repulsive force

without contact.

Any ideas?

[man] Chuck dude.

Come here and touch Dad's finger.

-Ah.
-Ow.

[Dallas] Yep, it's static electricity.

Negatively charged electrons
in Chuck's hair

made it stand on end
due to the repulsive force

between individual strands.

That spark was a textbook discharge

of static electricity.

And a moment he'll be talking
to his therapist about

for years to come.

And now our last question.

We know that forces
from static electricity

can repel objects,
but can it also attract them?

Yes, as this cat has found out.

The balloon gained a negative charge

when it was rubbed on the carpet,

and it induces a positive charge
on the cat,

by repelling the negative electrons
on its surface.

And as we all know, opposites attract.

So there you have it, non-contact forces.

All right, class dismissed.

[laughter]

[electricity crackling]

There's a rumor going around
that us snowmobile racers

are a crazy bunch
of thrill-seeking daredevils.

And I should know. I started it myself.

But it's true that I am never happier

than when I'm roaring
across the snow and ice

with the wind in my hair.

I know, it sounds amazing.

[rock music]

But as in all sports,
you'll find a mix of highs...

and lows.

As well as hits...

and misses.

You're gonna flood the engine, mate.

Yeah, told you.

Snowmobile racing is a potent c*ck
of traction and acceleration

served straight up over ice.

Sounds delicious.

And here's the science to explain

how it's all expertly blended together.

Snow and ice have a low
coefficient of friction,

so snowmobiles are designed
with a caterpillar track at the rear,

which has a large contact patch.

Its sharp points increase
pressure to pierce the ice

for extra traction.

The track drives the snowmobile forward,

and the skis at the front steer.

To perform well in a race,
you need both speed and control.

But accelerate too hard,

and the counter-torque could overcome

the force of gravity
and lift the snowmobile into,

for want of a better word,
a wheelie or even flip it.

It all comes down to the perfect balance

of speed, traction
and a complete lack of concern

for your physical well-being.

And don't accelerate too hard,

if you want to avoid
excessive counter-torque.

But has this guy been paying attention?

[man] Ahhh!

[Dallas] No. No, he hasn't.

Counter-torque lifts the front,

and when those skis are in the air,
there's no way to steer.

So like a rhino wearing rollerblades,

he ended up with lots of power
but no control,

meaning his race was over
before it's begun.

But if you do get going,
then getting your jumps right

can gain you valuable time in a race.

[man yells]

[Dallas] But only if you land them.

When the snowmobile leaves
the uneven ramp,

it begins to rotate,

and poor attachment means the rider
easily separates from it in midair.

[man yelling]

[Dallas]
At least snow makes for a soft landing.

The large contact pad
of the caterpillar tracks

allow some high-powered snowmobiles

to reach speeds in excess
of 150 miles an hour.

But even at 60...

you need to a braking distance
of almost 600 feet.

Well, that's it, settled.
Too dangerous for me.

I'm gonna trade in my snowmobile
for a snow blower.

[electricity crackling]

[engine revs]

I'm about to blow your minds.

You'll think that I'm fooling you

and using trick photography, but I'm not.

Think I'm joking?

See if you can spot the hidden animals.

[quirky orchestral music]

Did you see him?

Apparently there's a dog here,

hiding in plain sight.

No, not him.

And according to my notes,

there's actually a cat in this one.

Isn't nature amazing?

[cat meows]

Camouflage is a vital tool
for a lot of animals in the wild.

It can help them catch prey
or avoid predators.

But what is the science

of disappearing into the background?

Let's have a look.

Camouflage is an evolutionary adaptation

to help animals blend in
to their environment.

This can either be adaptive,

where an animal can change color
to match the background,

or simply being
a similar color and texture

to their native environment,
so they blend in.

And moving slowly and stealthily

helps them avoid being seen
and reduces noise,

which also helps them avoid detection.

Such behaviors have become instinctive,

because they confer
an evolutionary advantage

by helping animals to survive in the wild.

I use exactly the same techniques

when my wife asks me to take the bins out.

I try and blend in to the background,

keep quiet and still,

and hide away until she's gone.

It doesn't often work for me,

but let's see if this next lot
have better luck.

Somebody has shredded all
the toilet rolls in this house.

So far, there's no suspects.

By burying himself
under a pile of dirty laundry

and keeping still,
this mutt hopes to avoid detection.

[woman] I know.

[Dallas]
But his owner is wise to his tricks.

In the wild, surprising prey is essential
instinctive behavior for many predators.

But it's still useful for domestic cats.

[yowls]

[woman] Oh, oh, oh! Honey. Are you OK?

Lucifer. You're such a [bleep].

[Dallas] Lucifer here thinks
he's well-camouflaged

hiding in this dark cupboard,

and then he uses slow movement

so he doesn't alert Honey to his presence.

[yowls]

It's a classic honey trap.

My advice when you're going
for a jungle stroll is always the same.

If you're not sure what something is,

then don't poke it with a stick.

[man gasps]

[Dallas] Oh, and always take
a spare pair of shorts.

You know, just in case.

Anacondas are ambush predators,

so this guy is an expert at camouflage.

It's also worth remembering
that an anaconda

can eat a 120-pound deer,

so you might not want to get too close.

-[snake hisses]
-[man gasps]

[electricity crackling]

Let's just take a moment to remember

that science is built on uncertainty

and the culmination of things
not going to plan,

which means we should look
at the people in this program

as innovators, explorers, inventors.

So let's watch some science in action.

[lively fiddle music]

[boy] Ahh!

[man yelling]

-[screams]
-[woman] Oh, my God.

[yowls]

[boy] Ahh!

-[snake hisses]
-[man gasps]