06x20 - Motorcycle, Parkour and Stairs

[bunniefuu]

[Dallas, off-screen] This
is the Science of Stupid.

Yes.

[screams]

[Cameraman, off-screen] Oh.

[Dallas, off-screen] This is the show
where intelligent and idiocy

are intertwined.

[Cameraman, off-screen] Whoa.

[Dallas, off-screen] Our researchers of
the ridiculous reveal key scientific

principles, through the medium
of their own stupidity.

With their hilarious help,

we'll study the science
behind radius of curvature.

[man] Oh, wow.

[Dallas, off-screen] Viscosity.

[man] Ah.

[Dallas, off-screen]
And material strength.

In the face off between science and
stupidity, there can only be one victor.

So, pay attention.

This is the Science of Stupid.

In this show we'll explore
angular momentum,

visual fields

and friction.

But first this.

In 1953, Edmund Hillary and
Tenzing Norgay conquered Everest

and became the first men to stand at
more than 29,000 feet above sea level.

Mountains rise up to challenge man all
over the earth's surface,

and that's all
thanks to orogenesis.

This is the process by which mountains
are built over vast periods of time.

Mountains dominate the
earth's landscape,

they also provide a playground
for the bravest among us.

And without them there would be no
opportunity

to do extreme things like this.

Although, personally I'd be happier
going for a simple bike ride,

just maybe not down the
side of a snowy mountain.

Mountains can take millions of years to
form, now to get some idea of the scale

of what's involved,
think about this.

The rocks at the top of earth's highest
mountain

were formed at the bottom of an ancient
seabed.

Convection in the mantle
creates massive forces that move

tectonic plates over
the earth's surface.

Where they collide these vast and
unstoppable forces are enough to crumple

solid rock or overcome its
sheer strength at fault.

Over time rocks deform vertically and
are uplifted into mountain ranges.

A weathering and erosion help to shape
their characteristic peaks.

Mountains formed this way are also
sometimes called fold mountains

as the rocks are
folded into shape.

But how do those shapes
impact earth's inhabitants?

This woman is a keen
free climber but...

[screams]

Slightly less keen now.

Solid rock surfaces can offer
good friction, but this can

be reduced when they've been
smoothed by erosion.

Downward force due to gravity overcomes
friction between her hands and feet

and the rock and she drops.

[screams]

Ruining her friendship but
reducing her impact force.

[screams]

This sheep is enjoying the view
on the side of this mountain.

But that looks like
a precarious perch.

[woman, off-screen] Poor sheepy.

[bleats]

[Dallas, off-screen] Weathering and
erosion create a steep incline

so when the sheep
loses its footing

gravity is able to accelerate
it very effectively down slope.

[woman, off-screen] Poor sheepy.

[Dallas, off-screen]
Poor sheepy, indeed.

[man, off-screen] Riding on a...

[Dallas, off-screen] Will this
cyclist fare any better?

[man, off-screen] Oh he's going
to eat **** for sure...

...I hope anyway.

I told ya!

[Dallas, off-screen] Loose sandymaterial
is formed by

weathering and erosion over a long
period,

it offers low traction so there's little
resistance

to him sliding sideways when he turns.

[man, off-screen] I told ya!

[Dallas, off-screen] You did.

When I was a boy I often dreamt
of doing tricks on a dirt bike.

But unfortunately, it's a dream that
remains unfulfilled to this day.

And doing a flip in front of a crowd was
my ultimate fantasy, well one of them.

But if I'm honest I've never fancied
doing it on a quad bike or a skidoo.

Getting a flip right is
incredibly exhilarating.

[man, off-screen] Wonderful!

[Dallas, off-screen] And getting it
wrong is both painful and humiliating.

[man, off-screen] You all right?

[Dallas] The dirt bike flip
is one of those stunts that

involves many variables
and lots of physics.

So, unsurprisingly it's a
dangerous trick to perfect.

Before leaving the ramp, our man
must throw his weight backwards

to create torque that generates
angular momentum.

As he jumps from the ramp he's launched
into a parabolic trajectory,

in the air he can increase angular
velocity

by giving the rear wheel a burst of

acceleration and decreasing his moment
of inertia

tucking his body close to the bike.

But if he fails to generate enough
angular velocity

he will not complete a full rotation.

[man] Ah, ah.

[Dallas] In 2006 Travis Pastrana

completed the first successful double
back flip on a motorbike.

Unfortunately, Travis wasn't
available for our research.

A small ramp and a low approach speed

don't give our dirt biking dare devil
much time in the air.

To compound his problems, he doesn't get
enough angular momentum

and with his body far
away from the bike,

his moment of inertia is large,

so he rotates a little bit
slower than he'd have liked.

[woman, off-screen]
Are you all right?

[man] That hurt a lot less
than I would have thought.

[Dallas, off-screen] In 2016 Gregg Duffy

completed the first successful double
front flip

on a motorcycling competition.

Unfortunately, he wasn't available
either, or wouldn't return our calls.

[man, off-screen] You all right?

[Dallas, off-screen] This aspiring stunt
man fails to throw his body weight back

until after he launches
so doesn't generate enough

angular momentum for a flip and
once he's in the air he can't

accelerate that back wheel
enough to rescue the flip.

See.

If you're going to attempt
a flip on your dirt bike,

picking nice weather might make
up for the terrible bruises.

[man, off-screen] Are you good?

[Dallas, off-screen] His launch off the
ramp

fails to generate enough angular
momentum

to make it all the way round

and he doesn't make the
most of what he does have

by tucking his body in
close to the bike.

[man, off-screen] Are you good?

[Dallas, off-screen] I doubt it.

He's just been hit
by his own wheel.

[man, off-screen] Oh, [bleep].

[Dallas, off-screen] There's always
someone

who tries to drive on a snow day.

But what scientific principle is this
slippery slider about to demonstrate?

[Dallas, off-screen] Driving on
a snow day is never a good idea.

But did you guess what
scientific principle

this sliding sedan was
about to demonstrate?

[group] Oh.

[Dallas, off-screen] Well,
it looks like super powers

but if you said dynamic
friction, well done.

The car slides because ice has a low
coefficient of dynamic friction,

so there's very little
resistance to its momentum.

However dynamic
friction is still present

and offers an opposing
force to the car's tires.

And over time that frictional resistance
gradually decelerates the car.

So, the man only has to apply a small
opposing force to make it stop.

[group] Oh.

[Dallas] Here at the Science of Stupid
we are big fans of parkour,

although we don't recommend it unless
you know what you are doing.

But today we're looking at one
specific move called a lache.

It involves a person jumping to grip

a horizontal bar with both hands before
swinging

and launching off it again.

[Cameraman, off-screen] Oh.

[Dallas, off-screen] Some people
make it look rather easy.

[Cameraman, off-screen]
Swing, swing double. Woo.

[Dallas, off-screen]
And some people.

[crowd] Oh.

[Dallas, off-screen] Yeah, that.

A parkour lache requires a
great deal of strength.

Now that's not something for
the uninitiated to attempt,

especially not
in a playground.

Grip strength is needed to keep
a hooked shape with the fingers.

to keep them attached to the
bar throughout their swing.

The body becomes a pendulum,

exchanging gravitational
potential energy

for kinetic energy and
back again with each swing.

Releasing the bar, the body is launched

into a parabolic trajectory whose height

and distance is determined by
launch speed and angle.

The optimum launch angle for a
trajectory

with a furthest range is 45 degrees.

In a lache this is also where
half of one's kinetic energy

has been turned into
gravitational potential energy.

This researcher is very
keen to demonstrate.

[female, off-screen] Oh, ah.

[Dallas, off-screen]
How not to do it.

[laughter]

[Dallas, off-screen] He didn't have
enough gravitational potential energy

to turn into
kinetic energy,

his take-off speed was too low, so his
trajectory was slightly too short

to get a good grip
on the next bar.

[female, off-screen] Oh, ah.

[laughter]

[Dallas, off-screen] Should this
fully-grown man

be fooling around in a playground?

[screams]

[Dallas, off-screen] I think that
probably answers that question.

The grip of his right hand isn't strong
enough, his weight overcomes friction

and it slides off the bar.

His left-hand stays
attached a little longer,

creating angular momentum
that rotates him in the air.

Fortunately, no serious
damage was done.

And he gave his
friends a good laugh.

Well, more of a giggle.

[laughter]

Actually, it's just a chuckle.

And while you don't need
specialized equipment.

It is recommended.

Now it's time for your science lesson,

the part of the show where we take apart
one

scientific principle
to see how it works.

So, who can tell me what the
following have in common?

This inattentive ambler.

This mindless marksman.

And this speeding
selfie stick holder.

If you worked out that vision, or the
lack of it,

was what they had in common then give
yourself

a pat on the back because this lesson is
all about how the sense of sight works.

Our eyes are the organs
responsible for our vision.

Light is scattered off the objects
around us and enters our eyes

where it's detected, and information is
sent to the brain for processing.

Our vision consists of a central visual
field good for picking out detail

and our peripheral
vision which helps us

detect objects in motion
to the side of our gaze.

The visual information is sent to the
brain

where it contributes to our spatial

perception and spatial memory to help us
interact with the world around us.

I hope now you have a clearer view of
vision because it's time for a test.

Question one, what do we
use the sense of sight for?

We use sight for spatial perception and
constructing spatial memory,

so we can interact
with the world.

[laughter]

But not quite like that.

With his gaze directed downwards

he can't construct a complete picture of
his environment and

he fails to detect the lamp
post outside his visual field.

[laughter]

I think he's noticed
it now though.

Moving swiftly on, question number two,
what are the limits of our vision?

The answer is about 90
degrees to the side,

about 60 degrees up and
about 75 degrees down.

This means we find it hard to see
something coming in from the side,

above or below.

[meowing]

Luckily this junior Stormtrooper
was wearing a helmet.

[man, off-screen]
Are you all right?

[Dallas, off-screen] This guy.

Should look where he's going.

This preoccupied barman has a slight
upward gaze,

meaning the hole in the floor is at the
very

edge of his visual field,
so he doesn't see it.

Not the best way to get
a sore head in the pub.

And now for our third and final
question,

what do we do with the visual
information?

Well, the answer of course is that we
process it and react to it but often...

[speaking foreign language]

[Dallas, off-screen] We
don't do it fast enough.

A person's reaction time to visual
information

is about a quarter of a second.

Now, many things move a bit
faster than that, like chairs.

[Dallas] So, that is the end of our
lesson on vision, class dismissed.

[laughter]

[Dallas] In my teenage years I went
through a phase

where I thought I wanted to be a clown,

I even got the enrollment form
from my local clown college.

But when I realized I'd have
to master the unicycle,

I decided it wasn't for me.

Of course, you don't have to
be a clown to ride a unicycle.

In fact, it probably helps
if you're not because the

wig and funny shoes can
be quite distracting.

And once you master the basics, doing
unicycle hop ups

is one of the most popular tricks.

They take a lot of skill and if you get
them wrong you might end up

looking like a clown.

One of the keys to mastering a unicycle
hop up is having good core body strength

and a basic
understanding of physics.

The rider needs to maintain dynamic
equilibrium,

constantly moving his center of mass and

base of support to
ensure they stay aligned.

When jumping he generates a ground
reaction force to push off.

He needs enough horizontal
velocity and enough vertical

velocity to reach the
top of the ledge

and jumping sideways rather
than forwards means that

friction can more easily resist the
lateral forces being applied.

So, anyone who wants to hop their
unicycle

needs to know all about dynamic
equilibrium,

friction, horizontal velocity
and vertical velocity,

which is a lot of stuff to
keep in your head.

Especially when you need to
worry about reaction force too.

She might need a
bit more practice.

This hip hopper pushes down

to generate ground reaction force to
lift into a near vertical

jump but doesn't get enough vertical
velocity

to get her wheel all the way up and her

slight forward velocity
tips her over the edge.

This is one of our top testers and he
really does have an excellent technique.

He also seems to have mastered

the art of the unicycle hop up and those
obstacles seem to be

bringing the best out of him.

[man] [bleep].

[Dallas, off-screen]
Except that one.

He keeps his unicycle balanced

by maintaining dynamic equilibrium using
successive

bounces to bring his base of support
under his center of mass.

But jumping onto the
edge of the box

applies a force not aligned with the
box's base on the floor,

creating a turning effect that
easily rotates the box and him.

[man] Oh [bleep].

[Dallas, off-screen] When you're
doing tricks in the real world

you may find it's not that well-built,
but it can be quite heavy.

Jumping to the wall with a turn his
trajectory

is a little too short and a little too
low.

He tries to gain stability
by grabbing that beam.

But all he gets is trip to
the unicycle repair shop.

Stairs, we've all seen them, love them,

hate them, they're here to stay and
they're

designed to make it easier
to ascend a vertical distance.

Meaning getting up them should be as
easy as raising a leg and taking a step.

This pug has his own unique
technique, it might seem strange

but if it's not broken
then why fix it?

And this side flipping stair
climber is coping just fine.

[laughter]

But walking upstairs on an escalator

that's going the wrong way is no fun for
anyone.

Especially not her.

A bit late to
phone a friend now.

If like her you struggle with stairs,

you might find that a clearer
understanding of the

science might help.

Stairs split a vertical incline into a
series of flat steps

that are within the range of motion

of the human hip,
knee and ankle joint.

Our man needs to maintain dynamic
equilibrium

to keep his center of mass near his base

of support while friction on the flat
steps keep his feet in place.

Spatial perception allows him to
calculate

how high he needs to raise a leg;

a miscalculation can result in
a slowing force at his feet.

[man] Ah, oh.

[Dallas] Stairs come with risk

and some researchers have even gone so
far as to say that they

are the most serious accident hazards

that individuals encounter in the
everyday

environment, which is
why I live in a bungalow.

School is a place of learning.

And he's learnt not
to do that again.

This student's spatial
perception is off,

and he miscalculates how high
he needs to raise his foot.

[laughter]

It's night time here, let's see
if that makes it more tricky.

He's okay, her...

[man] Neve, come on!

[Dallas, off-screen]
Err, not so much.

Walking up the steps she leans too far
back

with her center of mass beyond her
base of support,

she tries to correct it but
misses her footing because the

floor was a little bit lower
than she expected.

[man] Neve, come on.

[Dallas, off-screen] Feeding your dog in
the rain can be a real pain.

Especially if your stairs
are a little bit slippery.

Running towards the steps he
builds up a lot of momentum

which applies a large
sliding force at his foot.

Bad news when you're
relying on wet steps.

Well, that's it for now and I will leave
you with this thought

from the author Douglas Adams.

'Nothing travels faster than the speed
of light,

with the possible exception of bad news

which obeys its
own set of laws.'

A little bit like these guys.

[music plays through credits].