07x02 - Vehicles, Unicycles and Kayaks

[bunniefuu]

[Dallas Cambell]
This is the Science of Stupid.

[klaxon blaring]

[man screams]

Yes,

this is the show where we dip
the stirrer of science

into a test tube of stupid.

-Prepare to watch amateur analysts...
-[woman screams]

...attempt daft experiments

with minimal preparation

and zero common sense.

[woman screaming]

-We'll reveal what went wrong...
-[glass shatters]

...and why

with the help of
scientific principles such as...

impact force,

-[tires squealing]
-[car crashes]

inertia, and...

-[man yells]
-[laughter]

...air pressure.

When the foolish collide with physics...

there can be but one outcome:

pain.

Watch out, it's the Science of Stupid.

[electricity crackling]

In this show,

we'll be looking at steering...

flexural strength...

[man screams]

...and center of mass.

But first, this.

[glass shatters]

[electricity crackling]

[glass shatters]

I want to make something very clear.

I love being on the water.

I do not like being in the water,

which is why you would never catch me
in a kayak or a canoe.

I mean, this all looks excellent.

But to do that,

you first have to get in the kayak.

Oh, and stay in.

[woman shouts]

So before you learn the difference

between your blade and your bow,

you're going to want to learn the
science.

As our man boards a kayak,

his foot applies a force to it.

Thanks to the low resistance
to movement on water,

if he applies too much force,

the kayak will accelerate out
from under him.

Once in the boat, he keeps low,

avoiding excessive sideways movements.

Because if the combined center
of gravity, this,

moves too far from the center
of buoyancy, this,

-he'll be swimming.
-[man yells]

Whether you're safely
on shore or firmly afloat,

you want to keep your center
of gravity in check.

But first, we must avoid
applying too much force

to that kayak.

-[man 1] Dude.
-[man 2] Hold on, man. Balance it.

[Dallas] Let's see
if this newbie's got the knack.

[laughter]

[woman, off-screen] Just sit.

[woman 2, off-screen]
You're not supposed to stand in a boat!

[Dallas] Clear, simple instructions.

I like it.

Shame he's not following them.

Oh, he's down.

[laughter]

But somehow, he's not out.

[man, laughing] I'm gonna fall.

[man, off-screen]
Put it sideways right there.

[Dallas] Oh, dear.

I'm not sure he looks
particularly confident...

[man, off-screen]
Oh my God.

[woman, off-screen]
How's he gonna get in?

-[man] Are you getting this?
-[woman] Yeah.

[laughs]

-[Dallas] And justifiably so.
-[man gasping]

[woman laughing]

By leaning his weight
onto the far side

of the canoe for support,

his center of gravity shifts
outside the center of buoyancy...

leaving him damp and defeated...

but his friends elated.

-[laughter]
-Hmm.

Of course, even if you manage
to get in the kayak,

at some point you'll have
to get out again.

This doesn't look promising.

She's clutching at straws--
uh, well, grass.

-[woman screams]
-[laughter]

[girl, off screen] Mama!

[Dallas] She starts well,

but her boat is too far away
from the shore,

and she applies just enough force to it

to end up with her center of gravity

neither over boat...

[woman screams]

-...nor land.
-[girl, off screen] Mama!

[Dallas] I wonder how our novice friend
from earlier is getting on.

[man, off-screen] Let me get
the boat under you.

Lift yourself up.

[man 2, grunts] Right.

[Dallas] Not so well.

[electricity crackling]

[creaking, clanging]

Now, then, if you are after an instant,

take-anywhere treat for your buttocks,

then look no further
than the inflatable lounger.

It's the ultimate
in air-filled relaxation.

[woman screams]

For some people.

Now, it's really just
a giant sealable bag.

Inflatable loungers sound simple,

but the two key elements
of inflating them and sitting on them

seem to be causing people trouble.

So here's some science to help.

To inflate, pull the lounger
in a straight line like this.

Once full, the pressure inside the
lounger

can be higher than outside

and will equalize
unless you rapidly seal it.

Take care as you sit on the lounger,

as your weight combined with
the force of your momentum

will compress the air inside,
increasing the pressure.

A decrease in volume
equals an increase in pressure.

That's Boyle's Law.

Ergo too much force
and the air ends up outside the lounger,

and you end up on the floor.

Now, let's let those loungers
loose and relax.

[woman] Hold on, Bec.

[Dallas] First things first,
simply inflate the lounger.

[woman] I'm confused.

[Dallas] It's very simple.

Weren't you listening to the science?

[woman] I was doing that

and that's going straight through the...

I've got two...

Or is it two areas
that I've got to blow up?

[Dallas] What? No, no, no, no.

You've already made a mistake.

Spinning around causes the lounger to
bend

and stops the air pressure
from building up inside.

[woman] Oh, it's going!

[Dallas] Yeah, and so am I.

This looks much more promising.

The lounger is inflated.

He's just got to sit down gently.

[laughter]

Oh dear.

Our jolly holidayer does sit carefully.

Still, the force of his weight
increases the pressure

enough to break the clips, and...

[laughter]

Pop goes the lounger.

She's managed it.

[laughter]

He's overcomplicated it.

Our man opts to drop rather than sit,

so the force from his momentum

is added to his weight
as he hits the lounger.

Just like Boyle's Law says,

as he falls and flattens the inflatable,

the pressure rises, and...

[laughter]

Maybe he should have worn the helmet.

[woman] There's the wind! There's the
wind!

[Dallas] Oh, back here, are we?

[woman] I don't think this is right.

[Dallas] That's what I've been saying.

[Bec, off screen] Roll it, roll it!

[woman] Oh, I've got it!

[Dallas] Thank goodness.
Quick, show us how it's done.

[woman] You'll have to help me get up,
Bec.

[Bec, off screen] Alright.

[laughter]

[Dallas] Well, to be honest,
I'm not sure the road

is the ideal place to be lounging.

[woman] Oh my God.

[electricity crackling]

[metallic clanging]

[Dallas] sh**ting hoops with your dad?

It's the perfect childhood memory.

[bell ringing]

But who can tell me what science
we're about to see play out?

[glass shatters]

[electricity crackling]

[glass shatters]

[bell ringing]

[Dallas] We asked you what science
we were about to see

this dunking daddy demonstrate.

If you said
"elastic collisions," you're right.

[man] Oh!

[Dallas] And if you identified
the target, two points.

[woman] You okay?

[Dallas] As the ball compresses
against the ring,

it stores its kinetic energy
as elastic potential energy

before transferring it back
to kinetic energy.

The ball's springiness means
most of the kinetic energy is conserved.

It's a highly elastic collision,

so almost bounces back to Dad.

Almost, but not quite.

Don't worry, he's fine.

[electricity crackling]

[engine revving]

Some consider the wheel
to be our greatest invention.

But for us rugged types,

it's got to be the continuous track.

They can handle any terrain: snow,

rough building sites,

slightly damp tarmac?

[woman, off-screen] Ooh.

[Dallas] Yeah... not so much.

This mighty invention
has helped us conquer the world.

But knowing they have is one thing.

Understanding how is quite another.

Tracks help large, heavy vehicles

distribute their mass
over a larger surface area,

thereby minimizing ground pressure.

This combined with their deep tread

means they can move more easily
across snow or mud.

Long tracks effectively allow the
vehicle

to climb over obstacles that
smaller wheels can't manage.

To turn, each track
is driven at a different speed

or in a different direction.

Known as skid-steering,

it allows them to maneuver on the spot.

So minimized ground pressure,
grippy tracks, and skid-steering.

All great stuff, providing
you know how to handle it.

Oh, a parade.

What a lovely way to celebrate
this miracle of engineering.

That was less lovely.

The steep ramp poses
little challenge for the tank.

But because the tracks are long,

the nose of the tank rises,
blocking the driver's view,

so he misjudges the steering.

He's absolutely tanked it.

When it comes to DIY,

now, I'm a bit of an expert,
and I can tell you,

this gentleman is crushing it.

Maybe more than he intended to.

This excavator is expertly
navigating its way

through the rubble
due to its low ground pressure.

However, when the pile
of debris gives way under it...

it can no longer support
the excavator's weight.

[man, off-screen] Uh-oh!

[Dallas] "Uh-oh" indeed.

Snowcats are such great fun.

Why wait for winter?

Don't look at me, mate...

or that might happen.

[laughter]

Skid-steering enables tracked vehicles

to turn in tight circles when
stationary.

At speed, however,

the steering levers
are trickier to operate.

Maybe he should have waited for winter.

[laughter]

[bell rings]

[clanging]

[bubbling]

Okay, settle down. Set--settle down.

Playtime is over.

I hope you've all got
your notepads at the ready,

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

the bit of the show
where we focus our microscopes

on one particular scientific principle.

Can you guess what it is
from the following?

This beer pong enthusiast.

[man] Yeah!

[Dallas] Poorly crafted furniture.

[woman screams]

And these novice woodsmen.

[man screams]

What were they expecting?

[grunting]

Yes, the answer is,
of course, flexural strength,

or the modulus of rupture,

which is a fancy way of saying,

"The ability of a material
to withstand bending forces

applied perpendicular to its length."

Here's the science.

As force is applied, wood flexes.

Fibers at the top are squeezed,
generating compressive stress,

whilst fibers below are stretched,
causing tensile stress.

The longer the unsupported section,

the greater the turning effect,

and so less force is required

to exceed the material's
flexural strength.

Brittle materials like this glass
don't bend much

before their flexural strength...

is exceeded.

Now, let's see who's been paying
attention with a little pop quiz.

Question one:

what stresses occur in a material

when it's being bent?

[drumroll]

[crowd gasping]

Yes, that's right.

It's compressive and tensile stresses.

This energetic koala is looking
for a new place to hang out.

But when he jumps on the branch,

the combined force
of his momentum and his weight

causes it to bend.

The top of the branch
is subject to tensile stresses

while the underside is subject
to compressive stresses,

until...

To be fair, he's not
a "koala-fied" scientist.

Question two:

if an object has a longer
unsupported section,

do you need to apply more or less force

to exceed the flexural strength?

This man has a simple goal:
to cross the stream.

[man] Steady myself.

[Dallas] Balance won't help you, my
friend.

Because as we all know,
the longer the unsupported section,

the less force you need to...

[laughter]

[wood creaking]

[laughter]

[woman, off-screen] And you're wearing
your best socks.

[Dallas] We must all
make sacrifices for science,

but that is too much.

And finally, question three:

if flexible objects bend under stress,

what will happen to a brittle material

when the flexural strength is exceeded?

Can you guess?

[woman screams]

Yes, it'll break suddenly
and without warning.

This young lady strikes a perfect pose

with her hands and feet
on the table's frame

taking some of her weight.

When she turns,
all her weight becomes focused

on the center of the table,
and the flexural strength

is suddenly dramatically exceeded.

[woman screams]

Luckily, she escaped
with just a small cut on her ankle

and a slightly bruised ego.

-[woman screams]
-Class dismissed.

[glass shatters]

[electricity crackling]

[Dallas] Unicycling.

It's a bit like learning to ride a bike,

just twice as hard
and with half the wheels.

But it is versatile.

It can you take you there...

onto that...

and even up there.

But when it comes to getting down again,

it can take you...

straight to the hospital.

[man, off-screen] You hit pretty hard.

[Dallas] Yeah, I think he, uh, noticed.

The unicycle stair jump trick,
or stair drop,

can be particularly dangerous,

especially for the unskilled,
untrained, and un-scientific.

A unicyclist is in unstable equilibrium,

constantly adjusting
to keep his center of mass

above his base of support for balance.

He applies enough downward force

to create the ground reaction force
needed

to clear the stairs.

On landing, the tire helps
absorb the impact force,

dissipating some kinetic energy.

The unicyclist is now back
in unstable equilibrium

and adjusts to maintain balance.

We've grasped the science,

and now to grasp a saddle.

Start small. That seems wise.

-[man grunts]
-Whoops.

Well, wearing a helmet was also wise.

Plenty of momentum
and ground reaction force

to clear the stairs, but as he lands,

he leans too far back

and can't adjust with
his pedals to find balance.

[grunts in slow-motion]

It's a shame you can't
get helmets for bottoms.

You know what they say.

Good friends don't let you do
stupid things...

[man grunts]

...alone.

On landing,
our first rider fails to absorb

and dissipate the impact force
and so loses balance.

And then his chum's unstable equilibrium

is made even less stable

by the carelessly discarded unicycle.

[man] Ow!

[Dallas] Well,
what are friends for? Really.

Of course, even if you manage
to do everything right...

sometimes things just go "wheely" wrong.

The height of the stairs meant
he built up lots of kinetic energy.

Most of the large impact force
was absorbed by the wheel,

and the rest was absorbed by his bottom.

Here's a thought.

Next time, maybe just walk
down the stairs.

[electricity crackling]

[metallic clanging]

Every once in a while,
a dance craze comes along

that is so popular,

everyone and their mother
wants to have a go.

This is Gangnam Style.

These guys are a little confused.

[man] Oh!

[Dallas] And now dazed and confused.

Now, I've never
actually done Gangnam Style,

and I'd love to have a go.

The best bit is the bouncing,

but that's also where your problems lie.

So before I give it a try,

I'm going to need a breakdown
of the science.

To perfect the signature bounce,

she exerts a downward force on the floor

to generate a reaction force
that overcomes gravity

and accelerates her into the air.

On landing, the force from her momentum

combines with her weight,

so the surface must be strong
to withstand the impact,

especially if she has backing dancers.

It must also be stable

so they can all maintain balance.

Okay, dancers, put your best feet
forward

and prepare to overcome gravity.

That young gentlemen in the shades

looks like he knows what he's doing.

Everyone follow his lead, yeah?

Wait, I thought we were doing
Gangnam Style,

not--not break dancing.

Uh...

[laughter]

This table is sturdy enough
to hold the group,

but all that jumping produces a force

greater than the weight of a grand
piano.

This exceeds the table's strength.

[laughter]

He's done with Gangnam Style.

On to the Running Man.

[laughter]

These boys look organized.

I reckon they've been practicing.

You're not joining in, girls?

[laughter]

Wise choice.

Dancing on a table with only one leg

means his base of support
is both small and wobbly.

The more the table wobbles,

the further afield his center
of mass moves, until...

[slow-motion scream]

You're supposed to bust a move.

[laughter]

Not bust a table.

So, when you've perfected your moves,

there is just one other thing to
remember.

It's not just the dancers
that are subject to gravity.

[glass shatters]

[electricity crackling]

[glass shatters]

I think it's time
to wrap this up, don't you?

Please remember, don't try
any of these stunts at home.

They are all stupid.
It says so in the title.

If you need any more persuading,

then please watch this.

[woman screams]

[man screams]

[laughter]

[man] Oh!

[glass shatters]

[man grunts]

[laughter]

[woman screams]