04x13 - Boat, Roller Skating and Dirt Bike Jump.

[bunniefuu]

[Dallas]
This is the Science of Stupid.

[reading onscreen text]

Yes, this is the show
that puts the "sense"

into ridiculous nonsense.

We learn the fun way,
while others learn the hard way.

As we dissect what went wrong and why.

With their help,

we'll shine a guiding light on
such scientific principles

as angular momentum,

sliding force,

-and pendulum motion.
-Ohh!

Science is a force to be reckoned with.

Mess with its laws,
and it will mess with you.

So don't try any of this at home.

Actually, don't try it at all.

Watch out!

It's the Science of Stupid.

[electricity crackles]

In this show,
we'll be looking at hydrodynamic drag,

directionality...

[screams]

...and off-center force.

But before we get carried away...

-[screams]
-...this.

[electricity crackling]

To me, there's nothing quite
like the glamour of car racing.

The smell of the fuel,
the efficiency of the pit crews,

the A-list fans,

and this is nothing

like the glamour of car racing.

[screaming]

[Dallas] But you've got
to start somewhere.

This grown man surely knows better.

[bleep]

[laughter]

[Dallas] Apparently not.

More adults showing
the kids how it's done.

[all cheering wildly]

I can see a pattern emerging here.

Yep, toy cars are the polar opposite

of a good off-roading vehicle,
but they do look fun.

So, if any of you are thinking,
"I'd like to give that a go,"

then you'd better understand the science.

Unlike a normal off-road car,

this toy car doesn't have suspension

to absorb the upward force
from small-scale bumps.

Add to this the small, hard wheels,

mean that even a little rock
gives a large angle of attack.

And let's not forget that
this is designed for a small child,

but with our man in the driving seat,

the combined center of mass
is raised further

above the car's short base of support,

making it more prone to rolling over.

So there you have it.

For success, all you need is to be wary

of the bumps in the road and keep an eye

on that center of mass,
and then it's just child's play.

So how will these grown men get on?

That'll be badly, then.

These guys couldn't avoid that bump,

and on landing, their high center of mass

easily fell outside the wheel base.

And a roll was almost inevitable.

Let's see what happens
when you add a couple of friends.

That looks fun!

[all screaming]

That looked slightly less fun.

These three guys
have a high combined center of mass,

so during the turn,

centrifugal force and friction
combine to flip them over.

[all screaming]

Let's see if this guy does
any better in his car

with non-existent suspension.

Nope.

The axles can't take his weight,

and his wheels come off.

And that's because
they're designed for a small child,

which he isn't.

But he is, so we should be fine.

Ah, ah. Hmm.

-All of which begs the question...
-[child cries]

...why did we buy Little Percy this
for Christmas?

I don't know.

[electricity crackling]

Have you ever wondered about the science
behind the art of trapeze?

No? Me neither until recently,

but now I do know, I want
everyone else to know.

So don your best Lycra,
dust down your hands

and pull up your leg-warmers
as we contort our brains

around the science of the trapeze.

[circus music]

This is where art meets science.

So graceful.

Do it right, and it looks like
you've defied gravity.

[man] Aah!

[Dallas] That's not right.

But what did he do wrong?

The key to success in trapeze
is good grip and muscular strength.

Mix it up with a proficient aim
and precise timing,

and you've pretty much got it.

So let's take a tumble
into the science of it all.

A trapeze is a type of pendulum,

and pendulum motion
describes the movement

of a mass hanging beneath a pivot.

As gravity accelerates
and decelerates the trapeze,

gravitational potential energy
is exchanged for kinetic energy

and then back again.

Trapeze artists exploit this
to achieve the desired amount

of horizontal and vertical velocity
for tricks,

allowing them to dismount with style.

So at the bottom,
all the gravitational potential energy

from the swing has been
converted to kinetic energy,

and the trapeze artist
is swinging at their fastest.

Sounds simple, but let's see
who's been paying attention.

[playful music]

Apparently not him.

Yes, this can be very dangerous,

so it helps if you start low

and...

enjoy the taste of crash mat.

[folklorico music]

This guy's got the hang of the swing...

[man] Aah!

But that dismount needs some work.

Lovely pendulum motion,
look at all that kinetic energy...

but a badly ex*cuted flip means
he gets a... nil points...

and a mouthful of sand.

OK, I think you're ready
for the flying trapeze.

[yells]

[Dallas] I was wrong, you aren't ready.

But these pros are.

Ah, the trapeze, bringing us humans
closer to true flight.

[audience gasping]

But here, not quite close enough.

In trapeze, timing is everything.

These two have perfectly timed swings...

but his fast fall means
they can't hold on.

You are fired.

Or should that be let go?

Oh, and one last thing,
as this young lady is demonstrating,

you can get 3D pendulums, too,

allowing more than one plane of movement.

[Dallas]
So get your timing and direction right,

and you can make knocking
over your little sister

look purely accidental.

[baby crying]

[electricity crackling]

[shouts]

[Dallas] He is certainly going for it,

but what scientific principle
is gonna beat

this enthusiastic street drummer?

[electricity crackling]

[Dallas]
We asked what scientific principle

this unpopular street performer
was going to show us.

You got it-- vertical momentum.

This showman needed to generate
sufficient vertical momentum

to clear the chair
by pushing harder against the floor.

He didn't, so he couldn't
complete the trick

and wow that audience of... none.

You might want an ice pack
for those bongos.

[electricity crackling]

I remember the first time someone told me

about sand-boarding.

"Try it," they said.
"What harm can it do?"

What they didn't tell me
was that it was completely addictive.

Sure, I started off with sand dunes.

-[woman screams]
-[man] Nice!

But I was soon hooked,

and even when I was
nowhere near the beach,

I found myself going down grassy hills,

and before I knew it,

the only thing that could get me going

was sliding down
the side of an active volcano,

like this guy.

[grunting]

-[man 1] You all right?
-[bleep] That hurt!

[Dallas] I bet it did.

But the sad thing is,
you'll be back for more.

[tearfully] We all will.

Honestly, this volcano-boarding
is a real thing

that real people do
on their holidays-- for fun.

It's fast, exciting,

and, in a number of different ways,
dangerous.

So let's have a look at the science,

and all that starts
with finding the right volcano.

Like this one. It's a cinder cone volcano

covered in loose
volcanic fragments called lapilli.

The surface has low sheer strength,

meaning that our volcano boarder
can easily carve through it.

But hit a bump,
and a limb can just as easily dig

into that surface,

applying an off-center force
and making him rotate.

And a low coefficient of friction

between him and the board
means that it's easy

to become separated from it
and take a tumble.

It's simple.

Keep your arms and legs inside the vehicle
to avoid a rotation.

Watch out for the low friction
between man and board

and do try to avoid any jolts or jerks.

[rock music]

Well, I bet that jolt
made him feel a bit of a jerk.

This boarder came across
a small bump in the surface

at high velocity,

which gave him some air
but also an awkward landing--

and some free exfoliation.

This is volcano-boarding at its best.

The large slope angle and loose fragments
allow the boarder to hit 50 miles an hour.

Yes, that is gonna hurt tomorrow.

The low sheer strength of the lapilli

is great for sliding through,

but if you try to put
your foot in it to slow down,

it'll dig in,
and you'll generate an off-center force...

[mellow music]

...and get a close look
at the local geology.

Ooh, is that an igneous formation?

How embarrassing.

This guy's turned up
in exactly the same outfit.

He only hits a little bump,

but due to the small
coefficient of friction

between him and the board,
they go their separate ways.

[man] Oh, dear.

[Dallas] Oh, dear, indeed.

[school bell rings]

[liquid bubbling]

All right, quieten down class.

Jones, put the Bunsen burner
back where you found it.

It's time for today's science lesson,

the part of the show
where we take a long hard look

at one specific scientific principle.

Right, 10 house points
for whoever can tell me

what the following have in common.

This Segway novice...

-Aah! [bleep]
-Ooh!

This impatient mechanic...

[screams]

And this speedy tractor.

[child] Wheels!

That's right, little fella,

they've all been bowled over by wheels.

It took me over three hours

to remember where I'd parked
the car this morning,

and I felt pretty stupid
until I remembered

that it took early humans
over 95,000 years

to come up with a wheel.

So who's the idiot now?

[rock music]

The wheel's gift to us is that,
when combined with an axle,

it can rotate independently

without the load needing to roll, too.

And rolling resistance is far lower
than sliding friction.

When larger wheels
and a suspension system is added,

you get the additional advantage
of a more stable load,

and wheels have
clear directionality of motion,

allowing steering.

Although that directionality
can be lost if there's no traction.

Right, OK, it is quiz time.

Question one, why is it imperative

the wheel is attached to an axle?

-[triumphant music]
-[man speaking indistinctly]

[Dallas] That's right.

No axle means little stability
for the wheel...

or for the person inside.

Oh, did I forget to mention
someone was inside the spool?

Sorry.

His weight was off-center
so he bounced around inside

before smashing out through the side...

which must have hurt.

Oh, look, it's back again.

It's got another one.

[wild music]

Question two, what happens
when you use small wheels?

[lively music]

Well, this can happen.

This fun guy's pallet truck
has small wheels

and low ground clearance,

so it was always going to be
a bumpy ride.

Still, for a while,
he did look pretty cool.

And question three.

Finally, what can be lost
if the wheel has no traction?

This guy is about to show us.

Yes, it's directionality of motion.

This dude's tricycle
had a loss of traction,

and therefore his three wheels

had no directionality of motion.

In other words, you can't steer
when you're in a skid.

Throw in a bit of downhill action
at high speed,

and you'll quite literally be down
in the dumps.

[playful music]

So that's it for wheels.

How did we ever cope without them?

[screams]

And that, ladies and gentlemen,

is a hole in "dumb."

[electricity crackling]

Cool, cheap, plenty of it to go around--

no, I'm not talking about me.

I'm talking about water.

And with water covering 70% of the globe,

there's enough for us all to dive into.

Water is over 800 times denser than air.

[man laughs]

Although, quite frankly,
it's not the only thing

that's dense around here.

It also makes for a romantic setting.

Ah, here comes the bride,
all dressed in...

[people shouting]

...sewage, seaweed, diesel.

[man] Help her!

Maybe animals will have
better luck in the water.

[meows]

No fish supper for you tonight, Ginger.

Yep, we are talking diving.

And unlike those we've just seen,
some animals are very good at it,

seamlessly transitioning
from air to water effortlessly.

So let's dive right into the science.

[rock music]

An animal experiences

relatively little drag in the air,
as particles are widely spaced.

But when it enters the water,
which is denser and more viscous,

the dog experiences hydrodynamic drag,

which slows her down more quickly.

So, for a deeper dive,

the animal needs to build up momentum,

either with lots of velocity
or lots of mass,

and to enter the water
with a streamlined body shape.

So building momentum

and perfecting that streamlined body shape

makes for a deeper, more impressive dive.

Let's see some of that animal
magic in action.

Darwin's Theory suggested
that this sure-footed penguin

has been sculpted by evolution
to cut through the water

with a streamlined shape.

[playful music]

[laughter]

Yeah, never trusted that Darwin.

Let's see if this four-legged friend

can handle the transition
from air to water.

[laughter]

Well, not elegantly.

He had plenty of momentum,

but that wasn't exactly
a streamlined entry.

Still, he got that toy,

and if you're a dog, then that's a win.

Who's the best boy? There's a good boy.

[mellow music]

Capybaras are the largest rodents
in the world

and spend much of their time
in the water.

They do like a bit of warning, though.

After the cheeky monkey's surprise push,

the capybara gained vertical momentum,

and he managed
a relatively streamlined entry

under the circumstances.

And finally, if you can't fly,

remember that momentum
when exiting the water

is just as important.

[laughter]

Funny, for an animal
that spends its life on ice,

you would think it would have
got the hang of it by now.

[electricity crackling]

Virtual reality--

it seems and feels real,
but here is the twist: it's not.

You could be being chased by a dinosaur,

riding a terrifying roller coaster,

or having the life frightened
out of you by a zombie,

all from the comfort of your own sofa!

[suspenseful music]

[rock music]

Virtual reality is just
good old-fashioned fun.

-[screams]
-[laughter]

[Dallas] Who doesn't love
an amusing trick, eh?

[screaming]

Yeah, all right, calm down.

Maybe take it a bit easy
on your mum, though.

Are you crazy?!

He's coming for me!

[laughing]

Right, so I'm ready to have
my senses stimulated,

but how do we really trick our brain
into having an immersive experience?

As always, science has the answer.

[dynamic music]

A virtual reality, or VR, system

supplies information
about a virtual environment

to the user via sight, sound,
and haptic feedback.

Haptics is the use of the sense of touch

to provide information to the user.

Success occurs when the user
is fully immersed

in the virtual world
without coming to harm.

But lose concentration,
and his body movements might work

for the virtual world
but not for the real world.

And that's not all.

If the equilibriums don't match up
between the two worlds,

then he might adopt a body position
that sends him off-balance.

Practicing your motor skills
will likely improve

how well you can resist this urge to move,

but for optimum success,

the most important thing
the user can do is to remain calm.

[calm music]

This guy's got it under control.

Aah!

Aah!

Or maybe not.

Aah!

Helped along
by his oddly hair-styled friend,

he lost his composure

and manipulated his body

into a position
that sent him off-balance.

Aah! Aah!

[Dallas] Ah, no losing composure here.

Oh, [bleep]!

Right, spoke too soon.

[bleep]

Utter terror has caused this chap's body
to be flooded with adrenaline.

Definitely more flight than fight.

In conclusion,
virtual reality isn't real.

It's just your brain being tricked.

[screams]

But the damage you can do
to yourself and your furniture is.

[electricity crackling]

Wow, watching people being stupid
is utterly exhausting.

So if you want to avoid public humiliation
and minor concussion,

then please don't try any of this at home.

And here's a reminder why.

[screams]

[playful music]

[screams]

Aah!

Ugh!

[screams]

Aah!

Aah!