07x11 - Bouldering, Wakeboards and Foam Pits

[bunniefuu]

[Dallas]
This is the Science of Stupid.

[sparking]

[klaxon blaring]

Yes, this is the show that extracts

nuggets of real science

from the minds of stupidity.

♪ ♪

-Sit back and learn...
-[yelling]

-as science's worst offenders...
-[exploding]

-break all the rules...
-[laughter]

-and suffer the consequences.
-[smash]

-We'll explore what went wrong...
-[thud]

-and why...
-[beeping]

-with the help of scientific
principles... -[revving]

-like Pascal's law,
-[splash]

-thermal expansion, and that cruel,
-[expl*si*n, screaming]

cruel mistress, turbulent flow.

[water flowing, splash]

Science is not to be toyed with.

Play with its rules
and you're playing with fire.

Watch out,
it's the Science of Stupid.

[electric crackling]

In this episode,
we'll be cushioning the blow

-with the impulse momentum theorem,
-[thud]

conducting inadvisable
research into adhesion.

Don't do this yourself.

We'll explore the
limits of reaction time,

-about... now,
-[thud]

but first this.

[electric crackling]

If you're interested in rock climbing,

but a little nervous about heights,

you may consider bouldering.

It's like rock climbing, but you're rarely
more than 20 feet off the ground.

And I, for one, found that comforting...

-[yell]
-[thud]

until I saw that.

Simply put, bouldering is
climbing over small rock formations,

crucially, without any ropes or harnesses.

The sequence of moves you
need to complete the climb

is called the problem,
and to solve any problem,

you're going to want masses
of material strength,

and a fistful of friction.

♪ ♪

Even the smoothest rock has
microscopic peaks and troughs

called 'asperities.'

Soft rubber climbing shoes
and the contours of skin,

called friction ridges,
lock into the asperities,

resulting in a high enough
coefficient of friction

to allow him to hold onto the surface.

The more force he applies
perpendicular to the surface,

the more friction he gets
and the more he sticks,

but there's a trade-off

because a force will
impart stress to the rock,

and if this overcomes
its material strength...

[crumbling]

he's going down.

Now, don't worry.

The most common injury
in climbing is merely

the ruptured flexor tendon pulley,
or climber's finger,

but I'm confident we won't see
any sore fingers with our lot.

Good work, but that surface looks

a bit tricky to get much friction on.

How about grabbing hold of that crack?

Yeah, that's the one.

-[crack]
-[shocked gasp]

Oh, my bad.

♪ ♪

Stress outer weak points,
and a fall from just 10 feet,

can result in you hitting
the ground with a force

of over twice your own body weight.

-[crumbling]
-Fortunately, boulderers use crash mats

-to protect from falls.
-[smash]

He just didn't land on it.

One of these rocks doesn't
have the material strength

to withstand much stress.
Can you guess which?

Oh, did you spot it?

-Yes, it's that little one there.
-[splash]

You gotta watch out for those.

-[man] Oh, oh! [laughter]
-[splash]

[Dallas]
But, more so for those.

Cracks can be helpful allowing
you to push with your feet

and pull with your hands,
maximizing force perpendicular

to the rock for more friction,
but if there's a weak point,

you're just pulling the rock off.

[man]
Oh! [laughter]

[Dallas]
He wasn't wearing a helmet either.

Maybe, it was so he could
fling that lovely hair around.

-[man, off-screen] Oh my God.
-[Dallas] I know, beautiful.

♪ ♪

[man, off-screen] The one on the
corner to the right-hand side,

right at the end.

[Dallas]
It's always good to have a friend below

to help guide you over problems...

-[gasp]
-[screaming]

And cushion your fall.

That little jump may have been
all the stress that rock needed

to reach its breaking point.

[screaming]

But, did it break their friendship?

-[man, off-screen] You alright? Yeah.
-[man 2, off-screen] Yeah, you alright?

[Dallas]
Nah, still best buddies.

[electric fizzling]

[rattling]

"Give me a place to stand
and I shall move the world."

So wrote Archimedes about the lever

in the third century BC.

But, as he well knew,

you can't have a lever without a fulcrum,

and if you're not sure what that is,

here are two of our top
researchers to demonstrate.

[man, off-screen]
Jump off it.

[Dallas]
Ready?

-[yelling]
-[laughter]

You're fired.

Okay, I'll explain.

A fulcrum is simply
the pivot in a lever system.

You can get either a mechanical advantage

or disadvantage,
depending on where you put it.

Let's look at the science.

♪ ♪

When the fulcrum's on one
end and the loads in the middle,

it will magnify the force
applied to the load.

With a fulcrum on one end, the force in
the middle, and the load at the far end,

the load will move a greater distance,

-so its speed is magnified.
-[snap]

[click, smash]

And when the fulcrum's
between the force and load,

if there's equal amount
of lever on either side,

well, you just get out what you put in.

[thud]

If a fulcrum helps increase the force,

we call the system a force multiplier.

If it increases the speed,

we call it a speed multiplier.

A classic example of a fulcrum
in the middle is the seesaw.

It doesn't multiply the force or speed,

making it harmless
fun for little children.

♪ ♪

[Dallas]
Ah.

[woman]
I'm really short.

-[Dallas] That doesn't make you a child.
-[indistinct chatter]

Remember, with no mechanical
advantage or disadvantage,

it's just a question of who
applies the most force.

-[man] Oh!
-[laughter]

[Dallas]
Yes, and that wasn't her.

Okay, so does anyone
know how to use fulcrums?

What's this? A slack line. Mousetraps?

[man] I think it's time for me to
take my shirt and pants off now.

[Dallas]
Uh...

Ah, I see. But, don't you
realize that those mousetraps

are actually 500 little speed multipliers?

[friend, off-screen]
Heck yeah!

[Dallas] Right, then you'll know that
whilst they don't multiply the force...

-[thud, traps snapping]
-they do multiply the speed,

-[laughter]
-and the pain.

[friend 2]
You're bleeding, he's bleeding!

[man]
Check this out.

[friend, off-screen] Oh, yeah.
It's just a flesh wound.

[man]
Just a flesh wound.

-[Dallas] 500 reasons right there...
-[man, off-screen] Oh, oh, oh!

[laughter]

[Dallas]
why you should never try this.

-[trap snaps]
-[screaming]

[man, off-screen]
That was a good one.

[Dallas] No, it wasn't.
And from one bad idea

to a man struggling with the concept

of how a claw hammer works.
Let's help him.

The fulcrum of the hammer
is here at the claw,

and will give him the mechanical
advantage he needs

to gently pry the nail out of the wall,

if he uses it as a lever
and turns it like this.

[man]
The hammer's coming apart!

[woman, off-screen]
What?

[Dallas]
But, will he do that?

Of course not.

[snap, crash]

[woman, off-screen]
Are you okay?

[Dallas]
At DIY, no.

At falling over,
he's a world authority.

[man]
[laughter] Ow.

[electric fizzling]

[creaking, crumbling]

[Dallas]
Whoa, there. Thank you.

Now, can you guess what
science this staircase cyclist

is about to demonstrate?

[shattering]

[electric fizzling]

[expl*si*n, crumbling]

[Dallas] Did you guess
the science we're about to see?

-[man, off-screen] Oh my God!
-[Dallas] Yes, it's Newton's first law.

The bike rapidly decelerates
when it hits the wall,

but Newton's first law dictates
that an object, this guy,

will remain in motion at the same speed
and in the same direction

until acted upon by an external force,

-[grunt]
-like gravity,

and then it's over to friction.

-[grunting, groaning]
-[clattering]

[clattering, electric fizzling]

[engine revving, tires spin]

[expl*si*n]

[Dallas] Over the hundreds
of pain-inducing activities

I've winced through on Science of Stupid,

it's occurred to me how much we,
as human beings,

fail to appreciate the softening qualities

of our good friend, foam.

♪ ♪

It's colorful fun for kids.

[shriek]

Ah...

And don't forget the big kids.

[shriek]

Aw...

And it's always there to
catch us when we fall.

-Oh-- ow. Ooh...
-[smack]

He made a full recovery, but ah...

-[smash]
-[yell]

Foam is a gas-filled polyurethane

that squidges when you land on it.

Foam pits are less painful
to land on as explained by

the impulse momentum theorem.

Impulse is the change in
an object's momentum

when it's acted upon
by a force over time.

The more time over which it is applied,

the less that force will be.

Cue the science.

♪ ♪

After launch,
his parabolic trajectory is set,

and must line up with the foam pit.

In the air, he tucks in to
reduce his volume of revolution,

the maximum space his
rotating body will occupy.

So, he comfortably
clears the edge of the pit.

As he lands, the foam applies

lots of small reaction forces on his body

over a relatively long period of time,

thereby cushioning the blow.

And tucking in, otherwise known as

decreasing your moment of inertia,

can also accelerate your spin speed.

But, I know what you're
thinking. Small jump,

vast pit, hundreds of
pieces of squidgy foam?

Easy.

Well, it is for this guy.

Oh, nice volume of revolution.

Arms and legs tucked nice and tight,
accelerating his spin.

But, it's not just your limbs
you need to worry about.

-[man] Whoa, whoa.
-[smack]

[Dallas]
Yes, your face is quite important, too.

Impressive high trajectory,

but it doesn't quite have the distance,

and as he increases
his volume of revolution,

-his head sticks out.
-[man] Whoa, whoa.

-[smack]
-[gasps, murmuring]

[Dallas]
And so to the landing.

["March of the Toy Soldiers" playing]

-Not quite how we did it in the science.
-[laughter]

Land face-first, and your entry will
mean that whilst you may still benefit

from impulse momentum's
soft, loving embrace...

[laughter]

your friends will have hours of fun,

trying to dig you out.

[bell rings]

[smash, splattering]

[hissing, bubbling]

Quiet at the back!
It is time for your science lesson,

where we unpack the particulars
of a scientific principle.

Can you guess what it
is from the following?

A flying man.

[speaking foreign language]

-[smack]
-[laughter]

-An icy girl.
-[crying]

[woman, off-camera]
Are you stuck?

♪ ♪

[Dallas] And a beautiful moment
between a husband and his loving wife.

[indistinct]

[screaming]

-[yelling]
-[woman] Oh, no, no, no.

[wailing]

[Dallas]
Aw, who said romance is dead?

[screaming]

He does.

[speaking foreign language]

Yes, that's right.
Today's principle is adhesion.

Two types here. Mechanical,
where one substance physically

-interlocks with another,
-[rip]

and intermolecular, like this glue,

where bonds are formed between
the molecules of substances.

Science, please.

♪ ♪

Electrostatic adhesion is an example

of intermolecular adhesion involving

electrostatic bonds between molecules,

which is the attraction
of two opposite charges.

Pressure sensitive adhesives,

like sticky tape,
use viscoelastic polymers,

bringing the adhesive
and surface close enough together

to form intermolecular bonds.

Some glues use both mechanical
and intermolecular adhesion.

They physically fill the pores
and gaps of a surface,

and form relatively weak
intermolecular bonds before drying

to provide strong joints.

[shatter]

Okay, it's test time. Question one.

You're about to see a form
of intermolecular adhesion,

but can you tell me which type?

[woman, off-screen]
Our cat loves balloons.

[Dallas] Good for you, but the answer is
electrostatic adhesion.

Thomas's fur loses electrons
to the rubber balloons

and becomes positively charged,

whilst the newly electron-ed up balloons

become negatively charged.

[woman, off-screen]
It's Thomas's birthday.

[Dallas] Yeah, and he's electro-ecstatic
about it.

Onto question two.

Sticky tapes are also
intermolecular adhesives,

but how do you get their molecules

to form bonds with other molecules?

Who have we got
to demonstrate this one then?

♪ ♪

-[laughter]
-Uh, was no one else available?

[ripping tape]

[man]
I'm bad and you know...

-[screams]
-[Dallas] Yeah, we do. We all know.

-See how tightly wrapped he is?
-[indistinct]

Sticky tapes are pressure sensitive.

Press them against
a surface so bonds are formed

between the molecules.
The more you press,

the more bonds are formed, and the more...

♪ ♪

-Yeah, they don't want to be apart.
-[screaming]

What a wonderful bonding
experience between colleagues.

Well, for her anyway.

-[screaming]
-Please don't try this yourself.

[laughing]

Now for question three. Can you name me

a type of adhesive that relies on both

mechanical and intermolecular bonding?

-[laughter]
-No, he hasn't fallen on an ice lolly.

-He's waxing his nasal hairs.
-[indistinct]

Sticking anything up
your nose is a bad idea,

and should only be done
by a medical professional.

[man]
I don't want to do it!

I don't want...

[chattering]

[Dallas]
I don't blame you.

-[man, off-screen] You gotta...
-[laughter]

[Dallas]
Wax acts a bit like glue,

which physically interlocks
with the hairs as it hardens.

[laughter]

[man]
Just pull it out already!

[Dallas] And intermolecularly
bonds, so that's like...

[man]
Don't mess around.

-[screaming, laughter]
-[Dallas] Double stuck.

[man 2, off-screen]
You got to relax.

-[Dallas] Until finally...
-[screaming, crying]

[laughter]

[man]
That hurt a little bit.

[Dallas]
Yeah, I'd leave the other one in, mate.

It's a... look you can pull off.

-[laughing]
-[ripping]

And that's your science lesson.

[screaming]

-Did you take it all in?
-[vocalizing]

I think that's a maybe.

[shattering]

[electric fizzling]

Often in life, we're told
to confront our problems head on.

But sometimes, it makes
more sense to dodge them,

particularly when those problems
are high velocity projectiles, like...

Soccer ba*ls!

-[smack]
-[laughter]

[man]
Ready?

[Dallas]
American footballs.

[boy]
Ow... My face!

[Dallas]
Or even... Oh boy.

-[thud]
-[man] Ow!

[Dallas]
One of those.

But even the most artful of
Artful Dodgers needs science,

and in this order.

Perception, reflex,

acceleration... Here we go.

♪ ♪

A human's field of vision
is around 190 degrees.

Since the projectile is within this field,

his brain sends signals to his muscles

so they contract,

with a reaction time of
about 0.25 seconds,

the average in humans.

[splash]

Due to his inertia,
it takes time to accelerate his body

away from the trajectory
of a projectile...

-[splash]
-if he can.

An eagle's eyesight is said to be

pin-sharp across two miles.

A cheetah can accelerate
naught to 60 in three seconds.

And a star nosed mole... [chuckle]

Has 230 millisecond reactions

from spotting to snatching prey.

None of the following
people can do any of that,

but maybe they'll get lucky.

♪ ♪

[woman]
Not today!

[Dallas] Alright, maybe not today,

but maybe someday, you'll focus
less on your friend filming you

and more on the ball rebounding

through your 190 degree field of view.

-[smack]
-[laughing]

[boy, off-screen]
It's dying all over the place.

[Dallas] Whatever you say,
but did you know that our field of view

only extends about 50 degrees upwards?

-[boy, off-screen] Oh my--
-[Dallas] That's much less.

-[boy, off-screen] Dude!
-[boy 2, off-screen] Sorry!

[Dallas] And it's even more
restricted when you're peering

through the viewfinder of a camera.

-[boy, off-screen] Oh my--
-[smash]

Gosh dude!

[boy 2, off-screen]
Did it break?

[boy, off-screen]
I think it broke my face!

-[Dallas] It didn't.
-[boy, off-screen] Oh my--

[Dallas]
But, the bottle was ruined.

-[boy 2, off-screen] Sorry.
-[Dallas] Okay, onto reaction times.

♪ ♪

It's backyard zombie
apocalypse training,

and Junior is flipping well acing it,

but can he handle the dodge?

Yes, he can.

Children tend to have slower reactions

than the 0.25 second reflexes of an adult,

but this kid is like a cheetah,

and a star nosed mole,
wrapped into one.

-This kid...
-[whip]

-[smack]
-more of a red nose mole.

[electric fizzling]

[rumbling]

Picture the sea.
You're on your wakeboard,

skimming over the water.

Your lovely friends cooing

as you carve past them
at 25 miles an hour.

You consider a flip, but it's a risk.

Get it right...

[man, off-screen]
Let's go Brado!

[Dallas]
And your friends will be like...

♪ ♪

[man, off-screen]
Yeah!

[Dallas] But get it wrong,
and they'll be more like...

-[yelling]
-[laughter]

So, you see, attempting a flip
on a wakeboard brings with it

a high chance of body
slamming into the water.

Hydrodynamic drag's your enemy,

and here's how you beat it.

♪ ♪

This wakeboarder twists
his upper body sideways,

pulling the handle towards him,
using tension in the line

to power the flip...

and generate enough angular momentum

to complete his rotation.

He lands,
leaning his center of mass back,

board pointing forwards
with the tip above the water

because if the board dips under,

hydrodynamic drag can result

in an unsightly turning effect.

So, to land elegantly,

board tip up and facing
the direction of travel,

we first need to get plenty
of angular momentum

and complete the flip.

♪ ♪

A little pull on the handle and...

-[yelling]
-[splash]

Lovely flip, but you need
to work on that landing.

If you don't want excess
hydrodynamic drag,

and you really don't,

then ensure your board doesn't do this.

-[yelling]
-[splash]

Maybe more airtime will help.

Let's try a ramp.

[splash]

Right, that didn't help.

The ramp gave him more
airtime for his rotations.

Shame they were
in the wrong axis.

-[splash]
-[laughter]

This looks promising.

-[splash]
-Yeah, mixed bag.

I mean, her center of mass
was all over the place,

but the tip of her board was up...

-[splash]
-Briefly.

[shattering]

[electricity fizzling]

[expl*si*n, shattering]

Okay, now please do not attempt

any of the dangerous
stunts you've just seen.

Society scoffed when
Charles Darwin first put forward

his theory of evolution
by natural selection.

It's now broadly accepted,

but it doesn't really explain
how this lot got through.

-[man, off-screen] Oh, oh!
-[splashing]

-[man 2, off-screen] Oh, my god!
-[crash]

[smack]

-[crumbling]
-[grunting]

♪ ♪

[screaming]

-[gasp]
-[screaming]

[whip, smack]

[splashing]

[boy, off-screen]
Oh, my-- Ow!

-[man] Oh!
-[gasp]

-[smack]
-[laughter]

[various screaming]

[smack]

-[smash, thud]
-[boy] I think you broke my face!