08x08 - Grass Boarding, Aerial Splits and Waterfalls

[bunniefuu]

DALLAS (off-screen): This

is the Science of Stupid.

Yes, this is the show that

detects the science hidden

in the stupid.

Learn as untrained researchers

examine the laws of science

and fail to understand them.

We'll discover what went wrong

and why it shouldn't have

with the help of

simple scientific principles

such as impact force,

momentum, and,

of course, friction.

Take on science and you

open the door to stupidity.

Watch out,

it's the Science of Stupid.

In this episode we'll be

examining the difference

between fear.

And phobia.

Between traction

and no traction,

and we'll be looking

at stability in water

or the lack of it anyway,

but first this.

I love cycling,

it offers so many modes

of exploring physics.

I've got my road

bike for the commute,

my mountain bike for the

trails and my trial bike.

DALLAS (off-screen):

For the ridiculous.

This is bike trials where

riders show off astonishing

feats of balance over

obstacles or at least try to.

The next time someone tells

you something is as easy

as riding a bike, tell them

they don't know what they're

talking about, unless

of course they've

understood the science.

We're talking center of

mass and Newton's favorite,

reaction force.

DALLAS (off-screen): First he

shifts his weight back pulling

on the handlebars to help lift

the front wheel whilst driving

down on the pedal to generate

a large reaction force

launching him into the air.

Before landing he applies the

back break to help keep the

combined center of mass of him

and his bike over the small

base of support at his wheel.

He then releases the break

to repeat the process.

There you go, it's a big

reaction force for the hopping

and a carefully balanced

combined center of mass for

the not falling over.

Good, simple physics but let's

see if our young trialists

were paying attention.

DALLAS (off-screen):

He wasn't.

Starting on one wheel gives

him a tiny base of support and

when he leans his center of

mass too far forward gravity

causes him to pivot, which

might have been less painful

if he'd bothered

to wear a helmet.

It's an odd choice of

location but go for it.

Good start.

Back wheel locked

ready for the big jump,

loads of downward force and

he's made it, momentarily.

On landing he was leaning

too far back which means the

center of mass

was, once again,

outside of the

base of support.

Maybe next time just bring

your swimming trunks to the

pool, like everyone else.

Here we go.

Good technique.

Great balance.

Oh, maybe the pool

wasn't such a bad idea.

He hasn't generated

enough reaction force,

so he lacks the momentum

to make the second wall.

Look, this clearly

isn't working.

Why don't we try going

down rather than up?

See, gravity is your friend,

but not checking what you're

landing on is your fault.

Maybe it's not the

jump, it's the bike.

So, let's try a different one.

Much better.

I think it's time we took

a break from watching the

scientifically challenged

and concentrate on one of

science's heroes, Tyler

Bradt, kayaker extraordinaire.

DALLAS (off-screen): He

wants to kayak over this,

Palouse Falls in Washington.

Thousands of cubic feet of

water pass over this fall

every second and drop

186 feet to the pool below.

To consider kayaking over

this you must either be a few

sandwiches short of a picnic

or a world record breaker.

We hope.

Oh, there he is.

The new world record holder

for one of the most dangerous

stunts I have ever seen.

Needless to say, even if you

do have 186 foot water feature,

don't try this at

home or anywhere else.

Falling off a waterfall is

the easy part but as gravity

initially accelerates you

down at 32 feet per second,

per second, it's surviving

that's the tricky bit.

DALLAS (off-screen): Our

kayaker must go over the falls

at the correct speed to give

gravity just enough time to

generate the angular

velocity needed to rotate

the kayak 90 degrees.

This angle minimizes

hydrodynamic drag,

so he experiences less impact

force and cuts through

the water.

It's also worth noting that a

kayak's stability is dependent

on keeping the center of mass

in line with the center of

buoyancy, which is in the

middle of its submerged

volume, otherwise.

Okay, science taught.

Let's see if our team of

wannabe record breakers

have learnt.

DALLAS (off-screen): He's

practicing the science with a

manmade kind of waterfall,

but the law of gravity

is the same.

The thin layer of water acting

as a lubricant combined with

the steep angle allows

gravity to do its thing.

It's not quite the 32 feet

per second per second of a

waterfall freefall but

he's only practicing.

Onto angular velocity, or

in his case the lack of it.

Launching too fast meant he

gained very little angular

velocity, hitting the

H2O at a terrible angle,

thereby maximizing

hydrodynamic drag,

which is bad as it brought

him to an almost immediate and

very painful stop.

Waterfall, tick.

Angular velocity, tick.

Stability, tick-ish.

It's an upside tick but

technically he's still got

himself into a

stable position.

It's just a shame his center

of mass is directly below his

center of buoyancy as his head

is the bit he uses to breathe.

Cheering without acknowledging

the person that's just saved

your life, tick.

MAN: Yeah!

DALLAS (off-screen): Even if our

wannabe record breakers do get

to grips with angular velocity,

hydrodynamic drag and stability,

like Tyler did, 186 feet

is just too dangerous.

Maybe it's better to

kayak something safer,

like a puddle.

Now then, can you deduce what

scientific concept this young

man is about to demonstrate

by jumping over his friends?

DALLAS (off-screen):

Did you work out the science he was testing?

That's right.

It's angular momentum.

As our jumper takes off he has

little angular momentum and so

would have landed on his feet,

but the beam applies a force

to his head causing him

to gain angular momentum.

Luckily his friends were

there to break his fall

and he was okay, in the end.

Avid Science of Stupid viewer,

and 32nd President of the

United States, Franklin

Roosevelt said,

'The only thing we have to

fear is fear itself.'

Well, he's obviously never

suffered from arachnophobia.

MAN: He's trying to get to you.

DALLAS (off-screen):

Just remember.

MAN: How's he doing that?

DALLAS (off-screen): They are

as frightened of you as you

are of them.

Apart from that

one, obviously.

MAN: It's on me!

DALLAS: Arachnophobia,

the fear of spiders,

is a funny old mix between

practical survival and totally

irrational behavior.

Fear isn't the enemy,

irrational fear is.

DALLAS (off-screen):

For example,

a fear of a big dog

bearing sharp teeth,

sensible but fear of a

placid small dog, phobia.

Fear of spiders is logical

as some are venomous,

in fact research suggests

it could be genetic.

Babies were shown pictures

of spiders and their pupils

enlarged, even though they may

have never seen one before.

It's part of the fight

or flight response where

chemicals are released into

the blood stream increasing

respiratory rates and blood

flow to the muscles preparing

the body to fight back.

Or in his case, flea.

Of around 43,000 different

spiders in the world less than

30 have ever k*lled anyone but

it's believe our innate fear

of them may have stemmed from

our cave dwelling ancestors

who might have had more

contact with the more deadly

and less incy wincy

of those 43,000.

Anyway, lesson over.

DALLAS (off-screen): Maybe

a nice glass of milk to

calm the nerves.

Because she didn't expect

to see a spider her

reaction is instinctive.

Flight and screaming.

MAN: Hello spider.

DALLAS (off-screen): Now, he

knows exactly what he's doing.

He's teasing this

jumping spider.

MAN (off-screen): A, attack.

DALLAS (off-screen): And

it's not called a jumping

spider for nothing.

This species can suddenly

increase blood pressure in its

legs so that they instantly

extend propelling it forwards

up to several times

its body length.

Which also causes a sudden

rush of blood in our

spider-botherer.

One particularly clean

researcher has discovered a

spider in his bath and

obviously he doesn't have a

phobia as he's

happy to poke it.

Not so happy anymore.

When his eight-legged friend

jumps in our bather gets a

heavy dose of fight

or flight chemicals.

Less relaxing

than bubble bath.

But remember fear

can be sensible.

Some spiders carry enough

toxins to k*ll an adult.

Others not so much.

Her fear causes her body to

bypass her rational brain to

react to the danger and escape

before she even realizes it

isn't a real spider.

But running on the spot?

Probably not the

best flight reaction.

BOY: I'm so glad we filmed that.

DALLAS (off-screen):

As are we.

Rallying is the ultimate

grass roots racing sport,

it takes road legal cars

and turns them into

racing machines.

DALLAS (off-screen): And

sometimes into spare parts.

You see, while some rally

events cater for your spec'd

up pro cars, others specialize

in vehicles that, well,

look a bit more like your

granddad's old bucket.

To win any rally it helps

to stay on the track and

professional rally cars are

packed with modifications to

help them navigate and

survive the toughest of races.

DALLAS (off-screen): Pro rally

cars have specially designed

tires with grippier

tread patterns,

and they're made from a softer

rubber compound that conforms

to a range of surfaces

to maximize traction.

Many pros also use

four-wheel drive,

distributing torque which

improves traction to aid

cornering and reducing the

risk of an unwanted understeer

or oversteer.

Shame that one was

a two-wheel drive.

In the professional realm

those enhancements are very

much standard and expertly

engineered to perfection.

DALLAS (off-screen): In the

amateur world it's more about

crossing your fingers.

The lack of traction in this

old car's hard skinny tires

causes it to oversteer and

when the driver tries to

correct this he

makes it worse,

which is why these purist fans

have decided to turn on him.

I'd run if I were you.

And it's why many rally

drivers favor the four-wheel

drive, of which that is not.

Front-wheel drives are more

prone to understeer as the

front wheels can lose

traction on the corner.

Luckily it won't be too

expensive to replace.

Hmm, lose gravely surface,

that should help us

drift into a ditch.

High performance rally

cars can hug a corner

at high speed.

This little hatchback

prefers to oversteer and

cuddle the ditch.

But upgrade that run-around

with all the right bits and

the trophy is in the bag.

He kept the steering

wheel right.

DALLAS: Surfing, exhilarating

stuff but sadly we don't all

live near the beach and surfing

without surf just isn't

the same, is it?

DALLAS (off-screen): Or is it?

It's not.

Nevertheless, it turns out

that surfing on grass is a

thing, not a particular safe

or advisable thing but a

thing, nonetheless.

Whilst there are less sharks,

the stopping bit can really

bite thanks to the dead eyed

fun k*ller we call 'friction'.

DALLAS (off-screen): An

initial input of forward

velocity, like

a running start,

will help overcome the static

friction with the grass and

then gravity can provide

additional momentum.

The lower the coefficient of

kinetic friction between the

grass and the board the more

effective gravity will be as

he glides over the grass.

Sitting or lying is easier

than standing as upright

surfers have a higher

center of mass,

which is trickier to keep

over their base of support.

Basically it's pretty much

the same as water surfing,

just a lot less salty

and a lot more hurty.

Okay, first up we need to

overcome static friction.

A little run up will do

but even better if we catch

ourselves a tube.

I mean, hill.

DALLAS (off-screen): Like

this one but without the

gigantic bush.

Gravity caused this rider to

pick up velocity very quickly

and his momentum meant he

couldn't stop in time to avoid

the shrubbery.

Maybe next time try

somewhere with less shrubs

and more space.

That's better.

Hang on, that's cheating.

Yeah, serves you right.

He appears to hit a rough

patch and the increased

kinetic friction

slows the board,

making it very hard to keep

his center of mass over his

base of support.

So, what if we lower that

center of mass by lying down?

Well, he didn't fall over

but since the wet weather

decreased the friction

between him and his board,

when the board stopped sliding

his momentum kept him going.

I made exactly the same

mistake this morning.

Get the friction right and

it's amazing what momentum can

do on grass.

Sand, that's a

whole other science.

If I asked you to stop

what you're doing,

get up off the sofa and do the

splits you would naturally ask

me to be more specific.

DALLAS (off-screen): Do I mean

a passive split where you use

the weight of your body?

No muscle work, just gravity?

Okay, I think we

get the point.

Or the split leap which

you perform in the air?

Less annoying

but probably more tiring.

I think let's look

at the leapy ones.

Now, the pinnacle of the

leaping splits is obviously

the grand leaping gracefully

into the air like a bird in

flight and landing with

the lightest of touches.

Of course, to master it

you need to understand

the science.

That's vertical velocity,

angular momentum and our old

chum base of support.

DALLAS (off-screen):

First she generates enough vertical velocity

at take-off for

sufficient airtime to fully extend her legs,

meanwhile generating plenty

of angular momentum

to bring both legs 90 degrees

to the upper body.

As she lands she uses the

muscles and joints in her legs

like shock absorbers, bending

to reduce the impact force

whilst insuring her center of

mass comes over her base of

support for stability.

And don't forget the

coefficient of friction

between the dancer's

feet and the ground.

In other words, don't slip.

DALLAS (off-screen):

Well, someone wasn't

paying attention.

Generating too much angular

momentum is practically a

guarantee of a center of mass

outside of base of support

style landing but whilst you

can reduce the impact force

with your legs, your

face is less effective.

Maybe try it without

so much spin.

Maybe try it without

smashing onto the floor.

Same problem, yep.

That's way too much angular

momentum and that is

definitely not landing

over your base.

Okay, maybe the

wood's too slippy.

How about a different

wood altogether?

Nice angular momentum,

room for improvement.

Her grand jetes were good

but her spatial awareness

needs a bit of work.

Maybe we should just forget

about all the jumping and

instead allow gravity to

ease us into our splits.

Well, they don't call

them splits for nothing.

Your leaping days

are over, my friend.

And that's it, we've done

all we can to help the

scientifically challenged.

Please do not attempt any of

the dangerous stunts you have

just seen.

As Benjamin Franklin is

alleged to have said,

'We're all born ignorant,

but one must work hard to remain stupid,'

and guess what?

These guys have

worked really hard.

(music plays through credits).