04x06 - Boats, Bicycles and Tablecloths

[bunniefuu]

[Dallas]
This is the Science of Stupid.

[reading onscreen text]

Yes, this is the show
where complex science

and complete stupidity combine...

as our band of intrepid investigators

challenge the boundaries
of scientific knowledge

so you don't have to.

With their assistance,

we'll examine the science behind
some key principles,

such as pendulum motion...

horizontal velocity...

and angular momentum.

So, sit back and prepare to be educated,

because this is the Science of Stupid.

[electricity crackling]

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

neutralization reactions...

and impact force.

But first, this.

[electricity crackling]

Some people love cycling
for the sense of freedom

and the wind in their hair.

Others like being environmentally friendly
and kind to the planet.

But for me, the best thing about cycling
has always been the shorts.

They're so silky
and surprisingly forgiving,

especially after a large lunch.

But cycling itself...

is fraught with dangers.

[screams]

See what I mean?

And that...

is the reason you'll never catch
me on a bike,

even with my special shorts.

Yes, for many people, going fast on a bike
is one of life's simple pleasures.

But throw a corner into the mix,

and it can be a recipe
for pain and humiliation,

which we obviously hate to see
here at the Science of Stupid.

So, pay attention and learn how to turn.

When turning on a bike,
centripetal force is created

by the friction between the tire
and the ground.

This inward-directed force
makes the bike travel in an arc,

but your body's inertia makes it
want to travel in a straight line,

leading to an outwards-directed
turning effect.

This is counteracted by leaning
into the turn.

The tighter the turn,
the greater the centripetal force

generated by the tires,

and the greater the angle of lean
needed to balance it.

Also, if you corner at double the speed,
you quadruple the centripetal force

and massively increase the odds
of your wheels losing traction.

Okay, so the faster you go,
the more you need to lean.

But lean too much, and you fall off,

and don't lean enough
and you'll also fall off.

Sounds tricky.

Ah, a hairpin bend.

Have all those cyclists
remembered to slow down

to reduce centripetal force
on this tight corner?

That'll be a no.

As well as not slowing down,
he's forgotten one crucial element--

turning.

Awesome! Yeah!

So remember to lean with the bend.

-[crowd whooping]
-[cyclists grunting]

[cyclist groaning in pain]

Just not like that.

[man groans]

The high speed
at which this road racer enters the bend

generates a large amount
of centripetal force.

But his lean overcompensates,
resulting in a loss of traction...

[groaning in pain]

...and any lingering hope
of looking cool.

[child] My friends are racing
for a hundred dollars.

[Dallas] That sort of motivation
should make this interesting.

[child] Anthony's in the lead.

But before you get too excited,
just remember...

-[groaning in pain]
-[laughter]

...uh, to look where you're going.

Don't worry, Anthony was fine.

He just lost the bet.

-[groaning in pain]
-[laughter]

[electricity crackling]

[creaking]

I love nearly everything about boats--

the gentle rocking motion,

the sound of the lines
ch*nk on the mast,

the constant smell of fish and diesel.

If it was up to me,
I'd live my life on the water.

If only staying on board wasn't so tricky.

[grunts]

[Dallas]
That happens to me all the time.

[screams]

And that.

It just shouldn't be this hard.

I'm really not sure
why anyone would be stupid enough

to jump off a perfectly good boat.

But if you thought that looked fun,

then please make sure
you're schooled in the science.

For an impressive leap
away from the boat,

our man needs to apply force
with his legs

at an angle from the vertical.

This generates a ground reaction force

that can accelerate him
both vertically and horizontally.

But fail to achieve the correct angle,

and it won't be the water you'll hit.

Adding a run-up can help
achieve the distance required,

but boats are in water,

and a wet deck can significantly
lower friction,

meaning less horizontal reaction force

and an ungainly rotation into the water,
thanks to gravity.

Did you know the world's
biggest cruise ship

towers over 70 meters above the waterline?

And if you were foolish enough
to jump off,

you would hit the water
at more than 80 miles an hour.

Our testers couldn't resist
the urge to experiment

on some smaller vessels.

But have they got their heads
around the science?

[suspenseful music]

[groans]

[Dallas] He hasn't.

This guy failed to take into account

the lack of friction
on the slippery deck.

Without enough ground reaction force,
all that effort is wasted,

as he rotates backwards under gravity.

Ha, ha! The elegant poise of a mermaid.

[screams]

And the execution of a clownfish.

Again, there is very low friction
on the deck,

so as our jumper launches,

she doesn't get the horizontal,
nor the vertical acceleration needed,

and so she enters the water...

[screams]

...slightly less elegantly than planned.

Water is denser than air,

and so bodies entering it from above
will experience a sudden increase in drag.

But how does that work in practice?

These boys are using hydrodynamic drag

to reduce their momentum
as they hit the water.

After a fashion, anyway.

Only his feet feel the full force
of the hydrodynamic drag,

which means the rest of his body
keeps going until it catches up...

painfully.

And for those rare occasions
where you have to jump onto a boat,

most of the same rules apply.

-[groans]
-[laughter]

He forgot that the wet deck
might have lower friction than the dock.

But who cares
when you've got moves like that?

So have you got it?

Yeah! Boy!

[Dallas] Oh, I give up.

[electricity crackling]

[creaking]

Can you guess what key
scientific principle

this donut-pulling doofus
is about to demonstrate?

[glass shatters]

[electricity crackling]

[Dallas] So, have you guessed
what science we're about to see?

If you said traction,
then move to the top of the class.

A donut relies on the back wheels
losing traction.

In order to do this, he keeps the wheels
spinning with enough torque

to overcome static friction.

But when the back right tire
hits the curb,

it no longer overcomes static friction
and catches,

launching the rider
painfully to the ground.

And that woolly hat
is offering minimal crash protection.

[electricity crackling]

[clanking]

As I am constantly saying to my wife,

I am a lover, not a fighter.

She never looks that impressed,

but maybe that's because
she doesn't know her biology.

It's a scientific fact
that be you man or beast,

you are equipped with the means
to protect yourself.

Prey animals are more likely
to be chased

and often use their hind limbs to deploy

a rear-directed defense
at a pursuing predator.

Like that.

Don't worry, though.

That was just a toy.

But most bipedal animals

can only kick out
with one leg at a time...

[screams]

I think they split up
fairly soon after that.

Yes, depending on the natural mode of life
of an animal,

it can either be optimized
for chasing or being chased.

When delivering a kick or a punch,

the idea is to produce an impact force

that is large enough to knock back
or damage your opponent.

This is achieved by increasing
the momentum of the striking limb

by having a large mass
and moving it at high velocity.

Depending on whether the animal
is the chasing predator

or the chased prey,

it can be adapted to reach out
and deliver force

in a forward or backward direction.

[whinnies]

Right, so there's the science.

But how does that work in practice?

It's rodeo time.

This should be fun.

Ooh, look, we've got a bucking bronco.

[neighs]

I said no photos.

The bucking horse is kicking down
on the ground

first to deliver powerful
two-legged kicks,

which are more than enough
to destroy that camera.

Clearly, it's not a good idea
to stand behind a horse.

-[groans]
-[woman chuckling]

I did warn you.

Uh-oh, a minor disagreement
between Mel Gibson and Russell Crowe.

This won't end well.

[man chuckling]

Get in there and break them up.

Get your boomerang out.

Kangaroos are optimized
for hand-to-hand combat.

Once they have hold of an opponent,

they use their large tails
to support their weight while they kick.

Stop it, lads, you're making me jumpy.

[bell rings]

[gurgling]

Right, you lot, settle down, settle down.

It is time for today's science lesson,

the part of the show where we take
one very specific scientific phenomenon

and really have a good, close look at it.

And if you want to know the theme
for today's lesson,

you're gonna have to tell me
what the following

foolhardy fellows have in common.

This expl*sive experimenter...

-[screams]
-[laughter]

[man] Go!

This spurting scholar...

...and this angelic alchemist.

[shrieks]

My eyes! Ohh!

If you said that they were examples
of extremes on the pH scale,

then you would be absolutely correct.

Yes, acids and alkalis are at the core

of some of the coolest
school experiments ever.

And here at the Science of Stupid,
we're all about being cool.

So litmus paper at the ready, please.

Concentrated sulfuric acid
has a pH of 0.1,

and like all acids
it turns universal indicator red.

Strong acids like this
are dangerously corrosive

and can dissolve many substances
like the plastic of this bath sponge.

At the other end of the scale
is potassium.

This is called an alkaline metal
because it reacts violently with water...

...producing an alkaline solution
of potassium hydroxide with a pH of 14.

It goes without saying

that you should never try
mixing chemicals at home,

as it can have deadly side effects.

Strong alkalis and acids
can be dangerous and corrosive,

but you might be surprised by how often

you come across their milder forms
in everyday life.

Question one:

what ingredient makes
super-sour candy super-sour?

All these brave test subjects
are doing their bit for science.

They're all experiencing quite
intense reactions to super-sour candy.

[moaning]

The candy contains
a small amount of malic acid,

which has a pH of 2.2,
the same as vinegar,

making it intensely sour.

Not surprisingly, our testers
all exhibit the reflex reaction

that I like to call facial scrunching.

How flattering.

Question two: what happens when an acid
comes into contact with a metal?

Animal testing is often seen
as controversial,

but we would never do anything to harm
a cute little bunny.

Like that.

Don't worry, it's not real.

This toy bunny has been filled
with hydrochloric acid and aluminium,

causing a corrosive chemical
reaction inside.

This produces hydrogen gas,
which builds up pressure...

until it explodes.

And now we come to our
third and final question:

what happens when you combine
an acid with an alkali?

One of our lead scientists
is going to demonstrate.

Oh, my God, I can't do it!

[groans]

The baking soda is an alkali
which has a bitter taste,

while the vinegar is an acid
with a sour taste.

When they combine,
a neutralization reaction occurs...

...making lots of gas and foam.

Water! Water, water!

Seriously, don't try this at home.

So that's the end of our lesson
on acids and alkalis.

Class dismissed.

[glass shatters]

[electricity crackling]

Do you know what really grinds my gears?

I'll tell you what--

needless vehicle accidents
caused by acts of stupidity.

Kind of like this.

It's pretty basic stuff.

Always put your handbrake on

before chasing
your snowball- throwing friends.

At least this time the lake's frozen.

[laughter]

Does that make it better or worse?

That was an elementary mistake,
but one that happens all too frequently.

A hill is an inclined plane

which causes some of the force
from the car's weight

to be redirected in a lateral direction.

When a vehicle is on a hill,

this lateral force combined
with low rolling resistance of the wheels

will make it begin to accelerate
downhill.

The steeper the slope,
the greater the acceleration.

Applying the brakes
allows friction on the brake discs

to resist the car's movement.

But if you want to stop in a hurry,
you need a large opposing force.

Just to be clear, when you park your car,

the first thing that you should do,
before anything else,

is to apply the handbrake,

especially if you're on a gradient.

It's pretty straightforward.

This driver is about to have
a really bad day.

[groans]

Yes, getting hit by your own truck
is unlucky.

But when the driver in front
sees his runaway vehicle,

he tries to save it
without putting on his own handbrake.

[tires screeching]

Which was bad luck for both of them.

The driver escaped with a cut leg,

but I think someone has it in for him.

A quick bit of free advice:

never park on any bridge
that opens.

Because there's not
a handbrake in the world

that could prevent this.

Ah, that's more like it.

Apply the brakes and enjoy the view.

What a perfect day.

Fore!

Five!

The gravity acting laterally
on the steep gradient

means that once the brakes give out,

there's nothing to prevent the buggy
from beginning its descent.

This feels like a scene
from an '80s sitcom.

Here's the mum,
and she's spotted some trash on the drive.

[screams]

Hey, that's not funny.

-[crash]
-[screams]

I thought this was supposed
to be a comedy.

Mum can't apply enough force
to stop the car.

Fortunately, its progress is halted
by an immovable object.

Unfortunately, so is Mum.

[screams]

But she was okay,

after a little lie-down.

[electricity crackling]

[creaking]

My children are always telling me

what a messy eater I am,
which is quite something

considering their favorite
piece of cutlery is a catapult.

Needless to say, there's a lot
of cleaning up after mealtimes

in our house,

which is why I've been working
on an alternative tidying technique.

Oh, and he did it!

That is what I'm aiming for.

Hey, ready?
One, two, three...

But that's more my level.

What kind of table cloth is this?

That's right, a bad workman
blames his cloth.

Pull it off, and your world
could be a tidier place.

But get it wrong,
and you'll end up with egg on your face,

and crockery all over the floor.

During a tablecloth pull,

there is friction between the tablecloth
and any objects on top of it.

While the cloth and the crockery
are stationary,

static friction resists sideways
movement.

But by rapidly applying
a large horizontal force

to the tablecloth...

he quickly overcomes static friction,

allowing the tablecloth to slide out
under a kinetic friction regime,

leaving the silverware where it started.

Now, this is an important skill
for me to master,

so I've got some of our
keenest researchers investigating.

[drumroll]

Yeah, well, that didn't work.

Dan from research
has applied too much force

in his attempt to enter
the kinetic friction regime,

and next time, he might want to check
the material strength of his tablecloth.

That's not a euphemism.

He's from our advanced science
department.

On the count of three.
One, two, three...

Top work.

He knows how to bring the house down.

His wide grip causes the tablecloth
to ruffle as he pulls,

creating too much horizontal force
at the base of the tower.

I think tablecloth-pulling
in a domestic environment

might not pass the viability study.

But that's no reason to ignore
the science.

There's always something you can
do with it.

Like this.

[whooping, cheering]

That was very clever.

That was less clever.

[glass shatters]

[electricity crackling]

That's all for now.

I hope you've been paying close attention
to the science,

because you've seen what can happen
if you don't.

[lively fiddle music]

[groaning]

[screams]