04x10 - Hedges, Longboards and Parking Gates

[bunniefuu]

[Dallas] This is the Science Of Stupid.

[reading]

Yes, this is the show where science
crashes headfirst into stupid

to see who will rise
victorious from the ashes.

-Argh.
-You'll see lack of sense

and scientific understanding

mixed with a lot of pain
for very little gain.

Watch as we shine a light
on what went wrong and why...

with the help of scientific principles
such as static friction...

[screams]

[Dallas] Hydrodynamics...

And gravity.

So, sit back, brace yourself, watch out,

it's the Science Of Stupid.

In the show,
we'll be exploring acceleration...

-Deceleration...
-[screams]

-And muscular strength.
-[screams]

[Dallas] But first this.

There are many, many things
that fill up my thoughts during the day.

Have I remembered to turn off lights?

Did I lock the front door when I left?

Just what is the best way
to snap a piece of wood in half?

[Dallas] There's martial arts style...

High flying style...

And this.

Now that seems frankly ridiculous.

When I see those, I think there simply has
to be a better way to snap wood.

Luckily, science is here to help.

[Dallas] He applies a force
to both ends of the wood

and once he's exceeded
its flexural strength,

it will snap.

As the fibers on the inside
of the bend are squeezed

and succumb to compressive stress,

those on the outside
succumb to tensile stress.

A thicker bit of wood
is likely to be stronger,

but you can break this by using
your leg to apply extra force.

The amount of force he needs
depends on the length of wood.

So a longer piece of wood
will have a longer lever arm

and he needs to apply
less force to break it.

So, simple, right?

Well, let's see it in practice.

[Dallas] This biker is ready
and eager to put science to the test.

-[crowd] Oh.
-Dude, he's out!

[Dallas] Well,
that's one way of doing it.

By hitting the board
in the center at high speed,

he very effectively concentrated

the bending force,
making for an easy snap.

He did, however, forget about
the reaction force

which impacts on the object
applying the stress to the wood

which, in this case, was his face.

-[indistinct chatter]
-Yeah!

[crowd cheering]

[Dallas] Luckily,
the only permanent damage

to our biker was to his ego.

[woman] Zachary, if you break that
chair, I'll break your neck!

[Dallas] Threats of physical violence

will not stop Zachary pursuing
a career in science.

He uses height to maximize
the force he can apply and...

[woman] Zach!

[Dallas] Luckily for the chair
and Zach's neck,

he didn't have enough force
to break either.

Zach!

[Dallas] Two people
should mean more force.

[groaning and laughing]

[Dallas] But obviously not enough.

They forgot that the shorter the wood,
the shorter the lever arms,

so they needed more force to snap it.

[groaning and laughing]

[Dallas] I'd suggest a refresher course
on Newton's Third Law...

Every action has
an equal and opposite reaction.

[laughing and groaning]

[Dallas] This can only end badly.

-[laughter]
-[man] I knew it.

[Dallas laughs] Me too.

By using their body weights
to apply force at either end,

they've involuntarily created
a very effective human catapult.

When my friend asked me if I fancied

a bit of scrambling,
I jumped at the chance.

Brunch has always been
my favorite meal of the day.

Regrettably that's not
really what he was asking me.

And then I spent the best part of a Sunday
making my way over a bunch of rocks.

Not everyone has my rock aversion,
but some probably should.

[Dallas] She should.

-Oh.
-Argh.

[Dallas] And him.

[shouting and groaning]

[Dallas] Oh, she definitely should.

Mama!

Scrambling on rocks
can take multiple forms,

many of them very dangerous
and with a real risk of you dying,

or at least hurting yourself badly.

So if you fancy having a go,
then I suggest

paying close attention to the science.

[Dallas] Scrambling is
all about stability and grip.

To support his weight,
he uses his hands and feet

to create reaction forces
against the rocks.

For an effective hand grip,
he uses the muscular strength

in his forearms to press his fingers
down onto rough rock to increase friction.

His foot grip also relies
on maximizing friction

through careful foot placement

with his grippy climbing shoes.

When climbing a vertical rock,
the further his center of mass

is from the rock,
the greater the turning effect

which will stress his grip...

until friction is overcome.

It's all about finding

the right place to climb
and the right kit to climb with.

After that, it's a delicate
balance of stability and grip.

Sounds simple.

[Dallas] And done right,

climbing can be full
of excitement, highs...

[shouting]

[Dallas] And lows.

As the climber moved up
the vertical cliff,

he started to rotate backwards
and the turning effect

meant that he lost his footing.

[shouting]

[man] Damn, dude, are you all right?

-[man 2] Yeah, dude, I'm fine.
-[man] You cool?

[Dallas] Luckily, this dude's fine,

but the dogs are still in counseling,

which is tricky as they're
not allowed on the couch!

[man] Go on, Callum.

[Dallas] Callum knows ropes
are great to keep you safe

and attached to the rock
face should you slip.

-[screaming]
-Oh!

[Dallas] Though in this case,
a little less contact

with the rock face would have been better.

Callum's grip strength wasn't enough
to support his weight...

-[screaming]
-And because he was on an overhang,

the rope applied
a vertical and horizontal reaction force

which turned him into a human pendulum,

hitting the wall with an impact force

equivalent to ten times his body weight.

To be a good scrambler

you need to be able to walk,
climb, jump...

Oh, my God!

[Dallas] And occasionally swim.

[laughing]

Our scrambler makes the jump,

but he doesn't have enough
friction between his legs and the rock,

meaning it was a watery end for him...

and his former best friend.

Even when you have the basics right...

remember that nature can be unpredictable.

[man] Wow.

[Dallas] Once a rock slide starts,
it can make everything unstable.

[man] Wow! Holy [bleep]!

[Dallas] Exactly. From now on,
I'm gonna stick to the indoor life.

This rather eager looking chap
is about to demonstrate

a scientific principle,
but can you guess which one?

[Dallas] Did you work out

the science this deckhand
is about to demonstrate?

It's angular momentum.

As he attempts to monkey vault
between the boats,

his horizontal momentum is redirected

when he pivots on his hands,
turning into angular momentum,

resulting in a bump and then a splash

and a refreshing dip.

[creaking]

I really, really love birthdays.

You get to gather all your
friends and loved ones around

to celebrate another year
and remind yourself

that you're speeding relentlessly
towards old age

and your eventual and certain death...

and cakes, there's always cakes.

[Dallas] Family cakes,

cakes on tables.

-Whew.
-Oh, my God!

[Dallas] And... cakes under tables.

It's such a waste.

But while to you and I cakes
are delicious sweet treats,

others use their tasty goodness

for acts of wanton prankishness
with the cake face smash.

Let's bring on some science.

[Dallas] A successful cake face smash
starts with his head

being accelerated down towards the cake.

Cakes tend to be soft
and deform around his head,

making the deceleration gradual,

which means he's less likely to be hurt.

But if his face misses
the cake and hits the table,

then deceleration will be more sudden,

resulting in a very sore head
and a spoilt birthday.

So aim is very important.

Not that we'd recommend
you try this at home

and if you were thinking about it, don't.

And if I can't convince you,
maybe these guys will.

[Dallas] Because many of you
may still think

that a cake face smash
is the perfect addition

to a birthday bash...

Whoo!

[Dallas]
Though I think she might disagree.

The birthday girl was suddenly pushed
with such force,

she had no time to react.

Luckily her face hit the soft cake,

slowing her deceleration deliciously.

You guys are good.

Am I the only one having apple?

[Dallas] Intensive research
tells us that variations on

the smash can work equally well.

Apple pie. A good choice.

Ali, here's yours.

-[all] Oh. [laughter]
-[screams]

[Dallas] Funny,
because I normally serve mine

with the cream on the side.

-[laughter]
-Oh, my!

[Dallas] Though,
just like the course of true love,

a cake face smash doesn't
always go according to plan.

[shrieks]

[laughter]

[Dallas] Attempting to avoid the cake

as it came towards him resulted
in our groom's losing balance...

illustrating that surprise
is an essential ingredient.

[screams and laughter]

[Dallas] As is a decent aim.

[bell rings]

OK, class, pens down, listen up,
nice and quiet please.

It's time for the science lesson,

the part of the show where we go
where others fear to tread

and delve into the deep,
dark, dank recesses

of one particular scientific principle.

Sounds rather exciting, doesn't it?

Right, so who can tell me what

these three things are demonstrating?

-[Dallas] High kicks.
-[boy] Woah!

-[groan]
-Mucked up flips...

and regrettable slips.

-Oh!
-[laughs]

[Dallas] Oh, he looks annoyed.

If you guessed Newton's First Law,

also known as the Law of Inertia,

then take five house points.

The Law states that an object
will stay in the same state of motion

or lack thereof unless acted upon
by a large enough force.

So let's check out the science.

[Dallas] When the balloon pops

the water is momentarily at rest
thanks to its inertia,

until the force of gravity accelerates it
towards the ground.

As a balloon flies through the air,

its inertia will keep it moving forward.

But when it hits another object,

the impact force overcomes its inertia,

reducing the momentum
as it rapidly decelerates.

An object with more mass has more inertia

and it'll be harder to change its motion,

and it's worth knowing the more momentum
a moving object has,

the longer it'll take
for friction or drag to decelerate it.

Right. On to question one.

What happens when a moving object
hits something with a larger mass?

[Dallas] Now let's see if these outdoors
men can assist us with the science.

[man] Straight line drive coming up.

[Dallas] What's a line drive?

[all shouting]

[Dallas] Oh, that's a line drive.

And it's a good example
of rapid deceleration.

When the can didn't release
from the elastic band,

it flew back towards him.

The fast moving can has a lot of momentum,

and the more momentum something has,

the more force it'll take
to decelerate it.

-[shouting]
-[bleep]

[Dallas] That's definitely
gonna leave a bruise.

Question two.

What do you need
to overcome an object's inertia?

Whoo!

[Dallas] Science is
about using your head,

but maybe not like that.

First, the force of gravity

overcame his inertia
and accelerated him towards the ground,

which then did an excellent job
of overcoming his new inertia

and stopping his fall

with a force equivalent to a bowling ball
dropped from a height of 16 feet.

-[man] You OK, Andrew?
-Yeah, I'm good.

[Dallas] Good but not great.

And now we have
our third and final question.

What effect does friction
have on an object's inertia?

[Dallas] Any ideas? No?

Well, let's have a look.

[shrieks]

[screams]

[laughter]

[Dallas] Accelerating briefly at 1.5 g,

friction acted on her feet slowing them...

[screams]

[Dallas] And then slowing her.

And that ends our lesson
on Newton's First Law.

Class dismissed.

Since I was a child,

my motto has always been
you name it and I'll ride it.

Yeah, it could probably
do with a little bit more work,

but it has served me well
throughout the years

and there's absolutely nothing
that gets my blood pumping

more than the shout of,
"Let's pop a wheelie."

[Dallas] He's popping a wheelie.

So are they.

And he...

wheelie needs more practice.

Since we first invented the wheel,
we've been pulling wheelies,

and of all the wheelies
that have ever been pulled,

the circle wheelie is my favorite,

and here's the science to explain
how to do one properly.

[Dallas] The rider accelerates rapidly

and uses the bike's counter torque
to lift into a wheelie.

He tilts the bike and it starts
to turn and fall inwards.

He then touches the brake
to straighten the bike,

stopping it falling to the ground,

then turns in again
and repeats this pattern

to turn in a circle.

The rider needs to maintain
side to side stability,

positioning his body so that
the combined center of mass

remains in the right place.

Coming out of a circle wheelie is

a question of repositioning
your center of mass

and bracing for impact
as the bike drops down,

which sounds a bit complicated.

However, with science,
anything is possible.

[Dallas]
Ah, now look at this graceful biker

pirouetting with poise,
good posture, nice leg extension.

Now for his grand finale.

Yeah, that seems less like ballet,
more like break dancing.

Our rider successfully
shifted his body weight

and maintained his side to side stability,

but as he lands
the bike drops too suddenly

and he doesn't have
time to correct his balance.

Of course, for some, just getting into
the wheelie is problematic enough.

This biker had two much
counter torque in his lift

and his bike went too vertical
too quickly.

With no time to adjust his center of mass,

he slid backwards but still held on,

forgetting the considerable friction

between skin and road.

But that's the sort of thing
that you only forget once.

It's a rookie mistake.

Like forgetting to keep
an eye out for obstacles.

Like that.

The rider failed to maintain
his front to back stability,

allowing the bike to lean
too far backwards,

causing his foot to slip off its hold.

But hanging onto the bike
allowed it to fling him into the wall.

Why do they never just let go?

When I hear the word "ice",
my thoughts generally turn

to a long cool drink
on a hot summer's day.

What doesn't instantly
spring to mind is messing around

on slippery surfaces
and ending up in traction.

But I'm funny like that!

[Dallas]
Though others can't wait to do it,

-[laughter]
-even when they probably shouldn't,

as we aren't built for walking on ice...

unlike the moose.

Just not that moose!

Sadly, mucking about on icy surfaces

isn't all it's cracked up to be.

Unlike those guys we've just seen,

some animals have the ability to
move with grace and agility across it,

and here's the science to explain how.

[Dallas] Penguins have smaller legs
and shorter strides,

which compensate
for low friction on the ice

by reducing the lateral sliding force
from their weight with each step.

A quadruped will have
an additional stability advantage,

with four feet offering
a large base of support

and a lower center of mass.

Another advantage is sharp claws
that can increase grip.

With tiny points of contact,
their body weight produces

a large local pressure that can
pierce the ice, increasing friction.

This allows them to exert
a larger lateral force when needed,

such as when running or jumping.

So, when it comes to mastering the ice,

four legs and claws are very useful,

as is lowering your center of mass.

[Dallas] But maybe not quite that far.

This pooch seems
to have got the hang of it.

[barks]

Eh, well, almost.

But it is windy.

The puppy's quadrupedal
advantage didn't help,

because his mass was too small
to create enough pressure for his claws

to pierce the smooth ice,

-[yipping]
-and so he struggles to gain traction.

And the black ice is
even worse as it's unexpected.

The deer's long legs

mean their feet stretch away
from their center of mass,

creating too large
a lateral sliding force,

especially when you're in a hurry.

And, of course, there's always one guy

who bucks all the science
and goes his own way.

Look at this renegade.

Though this acrobatic pooch has given up
his quadrupedal advantage,

he is able to apply
a greater downward force on his two paws,

allowing them to sink further
into the snow

and stopping him from slipping.

He does look really stupid, though!

And sadly that brings us to the end

of a staggering amount
of science versus stupidity,

and I think we all know
who came out on top.

So, if you don't want to become
one of the stupid,

then don't try any of this at home.

[grunts]

Whoo!

-Whoo!
-Oh!

[shouting]

[screaming]

-Ooh!
-[laughs]