04x01 - Pogo Backflip, Ski Cliff Drop In and Reverse Parking

[bunniefuu]

[Dallas]
This is the Science of Stupid.

[reading onscreen text]

Yes, this is the show
that combines highbrow science

and lowbrow stupidity.

It's where we get to watch
a smorgasbord of disasters

and then dissect what went wrong and why.

Through their pain,

we'll gain insights
into such scientific principles

as angle of attack...

the coefficient of restitution...

and traction.

Science is a force to be reckoned with.

Mess with its laws,
and it'll mess with you.

So don't try any of this at home,

or anywhere else.

Watch out...
it's the Science of Stupid.

[electricity crackling]

In this show, we'll learn
about angular momentum...

quadrupedal stability...

and the best use of an inclined plane.

But first this.

[electricity crackling]

As I learnt when I was
being taught to drive,

two wrongs don't make a right.

But three lefts do.

But like most learner drivers,

I soon realized
that driving along the road

isn't really the hard part--

it's when you have to maneuver

into a tight space that things get tricky.

That's it: mirror, signal, then maneuver.

-[upbeat banjo music]
-[man] Ohhh!

Remember to grip the wheel firmly

and do check your blind spots.

[man groans]

I think you're almost ready
for your test.

It's no wonder he needs
a bit of a sit-down.

Yeah, one of the hardest parts of driving
is safely reversing,

and there are two main things
that make it difficult.

Luckily for all you
learner drivers out there,

we've got the science behind the skill.

[wheels screeching]

Your first issue is the complications

of rear wheel steering geometry.

While reversing,
you are essentially steering

from the back of the vehicle,

meaning that to go towards an object,
you need to aim away from it,

and this often confuses beginners.

Secondly is visibility.

Fermat's principle states
that light always

takes the quickest path,
and that means in a straight line.

But the supporting pillars
holding the car's roof

blocks areas of your vision,
creating blind spots.

[wheels screeching]

So, rear wheel steering makes it
tricky to maneuver backwards,

not to mention
that the controls are reversed,

and Fermat's principle means
that you have to be very careful

of what's in your blind spots.

Let's see if they've
been paying attention.

In Finland, it takes two years

to get a full unrestricted
driving license,

and they produce some
of the best drivers in the world.

[swelling classical music]

-[car alarms blaring]
-Sadly, this isn't Finland.

This inexperienced driver
has forgotten that the controls

are reversed when you employ
rear wheel steering geometry

and then massively overcompensated.

Still, he got into the space in the end,

and that's what really counts.

That's nice to see.

It looks like someone's gonna
offer his granddad a lift home.

[engine revving]

Looks like he'd rather walk.

Ah, this looks better.

Plenty of space
and nothing behind to crash into.

[jazzy percussive music]

Ooh, that was close.

That's a bit too close.

Looks like this driver forgot
their Fermat's principle.

You've got to check your blind spots...

or that happens.

One of the hardest things
to learn as a driver

is reversing out of a tight space.

The important thing is to keep it slow.

[crashes]

Rear wheel steering is all very well

as long as you remember to turn.

A quick science reminder:

energy can't be lost,

only converted.

In this case, really expensively.

[electricity crackling]

Some people go for the ponytail,

others, leather trousers,

but when it's my time to relive my youth,

I'm gonna get a pogo stick.

A lot cheaper than a sports car

and they're ideal
for a mid-life crisis on a budget.

You can do it almost anywhere.

-[clothes ripping]
-[laughter]

[man] He's stuck on the door!

[Dallas] It's like aerial ballet.

Such grace.

[screaming]

The backflip is pretty much
the crème de la crème

of any pogo trick arsenal.

But to pull it off
requires an understanding

of some serious physics.

Pogo sticks store kinetic energy
from downwards velocity

as elastic potential energy

which is converted back
into kinetic energy

to return our man into the air.

To successfully flip his body

and stick all the way round,

he needs to generate plenty of energy
for sufficient height.

The combination
of this backwards movement

of his center of mass

and the upwards movement
of the rebounding stick

gives the jumper enough angular momentum

to get up and over.

But mistime it,

and you might find yourself
jumping into a hospital bed.

When you're doing gymnastics,

you can always rely
on the good old law of conservation

of angular momentum,

speeding up any flip by tucking in.

But it's harder to tuck in
around a pogo stick,

which makes it very easy to hurt yourself.

This is best left to the pogo pros.

You have to start by generating

enough elastic potential energy.

-[grunts]
-[man laughing]

[Dallas] And that's not enough.

It doesn't matter how good you are

at throwing your center of mass
backwards,

you're never gonna make the flip

unless you've sufficient height.

-[grunts]
-[man laughing]

[Dallas] Remember to throw
your center of mass backwards.

Good!

Less good.

He didn't create enough angular momentum

for a full rotation.

That's a pogo no-go.

This looks like someone
who can get it all together.

[grunts]

Well, he sort of did.

He got enough kinetic energy
to get the height needed,

enough angular momentum
to make the full rotation,

but he forgot to keep his feet
on the pegs

and all that lovely kinetic energy...

is just wasted on his face.

Most backflips in a row ever.

[Dallas] Ah, I see
you found the clip of me

trying to break the world record
for consecutive flips.

[heroic music]

Yeah, I remember I needed 18.

But strangely, I can't remember
how my attempt went.

[crowd gasps]

[Dallas] Yeah, yep,
it's all coming back to me now.

Ow!

[electricity crackling]

[metallic creaking]

What scientific principle

are these Antipodean swingers
about to demonstrate?

[man] This is gonna go so bad, man!

[glass shatters]

[electricity crackling]

[Dallas] We asked you
what science these grown men

and their paddling pool
were about show us.

[laughter]

[Dallas] Well, it's taught us
a bit about pendulums.

Our experimenter tries to jump

at the apex of the swing's arc,

but that's when it has the least velocity

and that means he doesn't have
sufficient horizontal momentum

to make it into the kids' pool.

Still, he's around supportive friends.

[electricity crackling]

[motor revving]

I don't usually like to talk about it,

but I do do a huge amount
for various charities.

For example, at the weekends,

I volunteer for the
Animal Mountain Rescue Service.

This sheep has got his head
stuck in the fence,

right at the top of this hill.

I've got you.

There you go, my woolly friend.

[sheep bleating]

[upbeat music]

[man] Yeah!

[Dallas] You know, "hero" is a word
that's often bandied about.

But in my case, it's probably accurate.

[man] Yeah!

Our friend, Woolly the Sheep, was OK,

but he was a bit of a rubbish sheep

because science suggests

that if one of us were to take a tumble,

it should have been me.

As every schoolboy knows,

balancing is all about
keeping your center of mass

above your base of support.

Four-legged animals
have an advantage over us humans

as quadrupeds have more points of contact

with whatever they're walking over,

which means the total area
of their base of support

is vastly increased.

And the lower the center of mass,

the more stable a body will be

which is why this cat is crouching.

So, any animals
with a low quadrupedal gait

should be very stable
and good at crossing narrow ledges.

Now let's see how this dog gets on

walking across this fairly wide pipe.

[lively music]

[woman laughing]

[Dallas] Butter paws.

Unfortunately,
his sprawling gait didn't help

because he couldn't get enough friction

between his feet and the pipe.

-Luckily...
-[splash]

he's a good swimmer.

[woman laughing]

I've often been told
that I have the reactions of a cat,

which sounds great until I realized

they meant this cat specifically.

-[meows]
-[thud]

With only its rear legs supported,

this kitten lost its quadrupedal
advantage

and found its center of mass

well outside its base of support.

-[meows]
-[thud]

[yowls]

Ah, the lion,

the majestic king of the beasts.

And, as it turns out,
quite a clumsy paddler.

When one of this lion's paws slips,

one end of his body
is no longer supported

and he topples.

He's all right, though.
The only thing damaged...

was his pride.

[bell ringing]

[glass shattering]

[liquid bubbling]

OK, settle down at the back, please.

Jones, see me after class.

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

the part of the show
where we put one specific

scientific principle
under our microscopes.

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

This teenage skateboarder...

[man] Oh!

This real-life fruit ninja...

And this clumsy commuter?

[man grunts]

They're all examples
of inclined planes or wedges,

simple machines that use geometry

to make moving an object easier.

Classic examples include the ramp,

a simple inclined plane,

and the axe, a more complex type

of inclined plane we call a wedge.

A ramp decreases
the amount of force needed

to move an object vertically

by increasing the distance
it has to travel.

The steeper the ramp,
the shorter the distance

an object has to travel,

but the greater the force needed.

Regardless of its steepness,

every ramp converts some
of the downwards pull of gravity

into horizontal force.

[dubstep music]

This axe is an example of a wedge

where the downwards applied force

is redirected horizontally.

Right, let's just check
you've all been paying attention.

Question one, when an object has to travel

a shorter distance to achieve
its vertical destination,

does it need more or less force?

[motor sputtering]

[man stuttering]

-Oh!
-[man] Holy [bleep]!

[Dallas] That's right,
the steeper the angle of the ramp,

the more force is needed to get up it.

[man] Holy [bleep]!

Yo, you OK?

Oh, my gosh.

Question two,

how does gravity affect
an object on a ramp?

This guy's about to find out.

[upbeat rock music]

[girl laughing]

[Dallas] The force on the tire
has two components,

one acting perpendicular to the slope

and the other acting down the slope.

This results in the tire moving
diagonally

and our adventurous skater
getting a soggy bottom.

[girl laughing]

Question three,
other than making it easier

for things to go up or down,

can inclined planes be used
for any other purpose?

Actually, before we answer that question,

let me just quickly
check on my home webcam

to see how the painters are getting on.

[man laughs]

[Dallas] I can't believe it.

They knew I wanted that room dusky peach.

[man laughing]

[Dallas]
The wedge shape of an axe

redirects the considerable
downwards force

into lateral force,
splitting the cans open...

and letting the pressurized
contents explode outwards.

So that's inclined planes.

Now excuse me,
I just have to quickly nip home

before they start on my bathroom.

[laughing]

[electricity crackling]

When I went on my last skiing holiday,

I cracked the nursery slopes
in just a couple of days

and then only fell over twice
on the green runs.

So I thought it was time
to give cliff drop-ins a go.

I wish I hadn't.

You can launch yourself off a precipice

and soar with all the grace
of a majestic condor.

[man screams]

Or you can plunge
like a flailing lemming.

Get it right, and it looks really cool.

But there is nothing cool
about picking up your teeth

with a broken arm,
so better listen to the science.

Skis are designed to have little
frictional resistance on snow,

so you can build up
lots of linear momentum,

which means that take-off
shouldn't be a problem,

but landing might.

While falling,
positioning your center of mass

in front of your feet

will help you stay balanced when landing.

Lean too far back,

and your slick skis
can accelerate out from under you,

converting linear momentum
to angular momentum,

which will rotate you backwards.

And while thicker snow
can reduce the impact force

from the drop,
too hard a landing will increase friction,

stopping your skis,
which will rotate you forwards.

So it's all about angular momentum.

You want to make sure you don't
rotate forwards or backwards.

Oh, and one more thing,

try to avoid rocks on take-off,
or guess what?

Exactly. More angular momentum.

So remember, just avoid the rocks.

[man screaming]

What did I literally just say?

[man laughing]

Maybe this next guy
will do better.

-[man screaming]
-[spectators exclaiming]

Or maybe he won't.

He leans so far back
that he manages to land on his head

with a force roughly equal

to eight-and-a-half times
his body weight.

Just another quick reminder,

if you're tempted to do this...
don't do this.

[upbeat music]

That body position looks better.

[man grunts]

Or maybe not.

Remember, the deeper the snow,

the more resistance you're likely to get.

Isn't science great?

If dropping in once looks hard,

then wait until you see multiple drop-ins.

The secret is to land, recover,

and then adopt the correct jump position

before gravity pulls you over
the next ledge.

[percussive music]

[man screaming]

[man 1] Ooh.

-Ooh!
-[man 2] Is he gone?

[man 1] Yep, he's all the way down.

-[man 2] Oh, there's a ski.
-[man 1] I don't think that's good.

[Dallas] My thoughts exactly.

From another angle, you can see
that on his second landing...

his center of mass is too far forward,

and that means he leaves
his skis in the deep snow.

But linear momentum and gravity

keep pulling him forward,

while angular momentum flips him over.

Incidentally, the world record
for roly-polies

is 75 in one minute.



Oh, how annoying.

So there we are.

A beginner's guide to ski cliff drop-ins.

[musette music]

The most elegant, painful way

to get down a mountain.

[man grunts]

[electricity crackling]

I don't want to sound paranoid,

but does anyone else feel like
doors are out to get them?

[lively piano music]

[shouts]

[cackles]

[laughs]

There, I knew it.

People are always making out
that moving from room to room

is easy, but it's not,
and science tells us why.

Most doors rely on hinges

and they are deceptively complicated.

Hinges need to resist
the vertically-oriented

turning force that pulls
the door towards the floor,

while allowing the horizontally oriented

turning forces so it can open and close.

When dealing with a jammed door,

as long as it should open away from you,

then the best place to kick it

is opposite the hinges
just below the lock.

This helps to maximize the turning force

and makes you look like a hero.

So it's all about turning forces.

But even when you know that,

doors can still be a little...

tricky.

Now where on earth is Susan from Accounts?

I asked her for the Peterson file
an hour ago.

Ah, here she comes.

[upbeat music]

[woman screams]

Susan hits the door's weakest point,

just below the lock opposite the hinges.

But pushing down on the handle

added to the vertically-oriented

turning force,.
and it was too much for the hinges.

That's the thing about Susan.

She's small, but strong as an ox.

[woman groans]

Terry from IT
has already been warned

about coming to work dressed as a chicken

and has been summoned to the boardroom.

-Oh!
-Oh!

[screaming]

I thought they were
gonna show him the door.

Our giant chicken friend

thinks this is a hinged door...

so he tries to apply

a horizontally-oriented turning force.

But a sliding door
is not designed for this,

so it falls off the rail,

allowing the vertically-oriented
turning force from gravity

to do its thing.

[screaming]

Glass doors are the worst.

The problem is that glass
is an amorphous solid,

which means the molecules
are arranged randomly.

Without any tiny crystalline
surfaces to bounce off,

light passes straight through,

and that makes glass rather hard to see.

[lively music]

When it's brighter outside than inside,

your irises shrink to let in less light

and that can make spotting
glass even harder to do.

Still, she should know by now

where the door is likely to be.

It's the sort of social cue
we pick up early on.

[lullaby music]

There you go, you're learning.

[electricity crackling]

Well, I think that's quite enough science

and stupidity for one day.

Please take note,

it would be extremely unwise
to attempt any of the stunts

you've just seen, and here
is a quick reminder of why.

[lively fiddle music]

[grunts]

[man screams]

[girl giggling]

[man screaming]

[man] Go!