02x04 - Half-Pipe Wipeouts

[bunniefuu]

[Richard, off-screen]
It's the Science of Stupid.

[Richard, off-screen] Yes, this
is the show that brings you

the parallel universes
of science and stupidity.

[screams]

Over the next half hour,

we will look at
science-based stunts.

And explain
where they went wrong.

We'll learn about
scientific principles

such as hydroplaning
and flash points.

[screaming]

Study buckling.

And sliding friction.

[screams]

If you're rough with science,
science will be rough with you.

So mosey on down for
the Science of Stupid .

In this show, we'll
look at horizontal

and vertical velocity.

Moments, to forget,
and center of mass.

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

[Richard]
But first this...

[cries]

When it comes to
gymnastics, I'm a lone wolf.

If I'm out there doing
back flips or somersaults,

you won't find
me asking for help,

and here's why.

[screams]

[laughing]

[woman] Ow.

[Richard, off-screen]
He's back.

Has he learned
from his mistake?

[man] Whoa!

[Richard, off-screen] No.

[crowd gasps]

Ah, he must have
learned by now.

[man] Oh... [bleep].

[Richard, off-screen] I
think we've seen enough.

Of course, not everybody
has my gymnastic prowess

and for those people, which
is most people actually,

a little scientific
assistance might go a long way,

starting with the turning effect
of a force known as a moment.

[Richard, off-screen] A moment occurs
when the lifter applies a force

that isn't through the
jumper's center of mass,

causing him to rotate.

The assisted front flip
also relies on a moment.

Here, the force is applied
through his hands

and the harder
the assister pulls,

the faster the rotation.

That's all very well, but you
are relying on the assister

to have the strength to help give you
enough height to rotate.

You see, lone wolf,
it's the only way.

[Richard, off-screen] But I
do hope I'm proved wrong.

These two don't give
me much hope though.

Yep, it's as expected.

A late lift means the
assister provides a moment,

but not much height,
so there's not enough

air time to rotate around.

It's a wedding.

How better to show your
joy than with a back flip?

And then spend the
wedding with a ripped suit

and grazed face.

If he'd stayed tucked in, he
would have rotated fast enough

to land on his feet.

Not easy in that suit, though.

Ah, sand should provide
a nice soft landing.

But not for your face.

Too much rotation equals
mouth full of sand.

Gather round girls,
this is how it's done.

Nothing to see here, just
a little over rotation.

Back flips are
clearly too hard.

Let's try
an assisted front flip.

Right!

Too much lift from
the assister means

too much rotation
by about 90 degrees,

and a carpet burn
on his chin.

[laughing]

Let's not overdo
the rotation, guys.

A moment he's
unlikely to treasure.

Not enough pull from the assister and
a lack of effort

from the jumper means
there isn't a big enough

moment to rotate him around.

I could really do with
a confidence boost.

Let's finish with a success.

Yes, yes, yes, yes, yes!

Oh my goodness, we're
going to do it.

Oh, thank you very much!

Everyone managed to nail
their moments,

but you had to let me down,
didn't you?

Usually when I see
scooters they're being

ridden by children or
overweight businessmen,

but there are people
who use them for tricks

like grinding, for example.

Sounds unpleasant, and the
consequences certainly can be.

[Richard, off-screen] The boy
experiences 14-G

when he hits the ground,

similar to what a fighter
pilot can experience

when he hits
the ejector seat button.

Yeah, I would advise against
trying this, but you might be

asking yourself "Is there some
science for guaranteed safety?"

Well, no, there isn't, but
there is some that could help.

[Richard, off-screen] To grind on a
scooter, he must keep his center of

gravity above his base,
in this case a narrow rail.

Subtlety shifting his body
weight, he can correct

the position of his
center of gravity.

The wider apart his
feet are, the bigger

the corrective effect
of his bodyweight

and the easier it is
to stay balanced.

So center of gravity
over base and legs apart.

Simple, but I have to admit the idea
of scooter grinding

still doesn't make
me comfortable.

So before we start,
a little commonsense.

And without wanting
to state the obvious.

[Richard, off-screen] First, make sure
the rail is clear of other people.

[screams]

And, second, don't miss
the rail completely.

Especially if that rail
leads to a main road.

Hopefully, that'll save
a few broken bones,

but I still think we need to
start slowly with this trick.

Maybe we should begin with
a nice gentle horizontal bar.

[Richard, off-screen] This
looks relatively simple,

but perhaps
not simple enough.

Hopefully he'll
have more luck.

Although technique is
probably more important.

Going down forwards means
a wide stance is impossible.

Flat rails were a huge
failure, but what happens

when a diagonal
is thrown into the mix?

That does.

As he rotates backwards,
his center of gravity goes

behind his base, resulting
in very painful landing.

One of these days, one of
our researchers is going

to surprise us
and nail it.

But not today.

Because his center of
gravity is too far forwards,

he's falling the whole
way down the rail, ouch!

The time has come to combine
diagonal and horizontal bars.

When a scooter rider
goes from one to the other,

he experiences vertical
reaction force as he hits

the horizontal.

Nasty, but the idea is to absorb
all that force by bending

the knees on impact.

Well, that's the idea anyway.

[Richard, off-screen]
Fingers crossed.

I think we saw that coming.

This chap only bends one
knee and so can't absorb all

of the reaction
force from the bar,

but the pavement does.

Can this guy absorb
that reaction force?

No, but he beat
his long jump PB.

As he hits the
horizontal rail,

there is a reaction force that
sends him up and off the bar.

But don't worry,
his phone was fine.

[groans]

Who can guess what
scientific law this man

is about to demonstrate?

[Richard, off-screen]
This man

is demonstrating
Newton's Third Law

that states that
for every action,

there is an equal and
opposite reaction.

[screaming]

[expl*si*n]

The firework spews out
hot particles and gas

at temperatures reaching over 2,000
degrees Fahrenheit,

creating an equal and
opposite reaction force,

which propelled the
firework upwards.

Playing with fireworks,
extremely dangerous,

extremely stupid.


road traffic deaths

happen amongst motorcyclists.

It's dangerous enough going
fast in a straight line,

but throw in a tight corner

and you could
be heading for trouble.

[announcer over loudspeaker]

[crowd gasping]

[Richard, off-screen] Especially if you
ignore the corner.

[man, off-screen] Yeah.

Motorbikes are known for their speed,
but with extra speed

comes extra danger.

You see, twice the velocity

means four times
the energy on impact.

So if a biker accelerates from ten miles
an hour to 80 miles an hour,

he'll have 64 times as
much energy on impact.

But cornering isn't
just about slowing down.

Here's the
science to show why.

[Richard, off-screen] To turn, a
motorbike needs centripetal force,

which is provided by
the frictional force

between tires and road.

By acting at the ground,
rather than the center of mass,

the centripetal force
has a turning effect.

So the biker leans his weight
to provide a turning effect

in the opposite direction
and stay balanced.

The faster he's going
or the tighter the bend,

the more he needs to lean.

Get that wrong and you and
your bike could be parting

company in a number of
unpleasant ways, including

the low side fall, where
a wheel slips whilst

you're leaning into a corner,
or the high side,

where the back wheel briefly
loses friction then regains it,

jerking you off your bike.

High side, low side,
either side,

it's gonna end in tears.

[Richard, off-screen] Oh,
looks like a pro race.

I hope these guys
know what they're doing.

And that is a
big low side crash.

Because he's going so fast,
he needs more centripetal force

to make the bend,

but he can't get
the friction he needs

and he overdoes his lean.

It looks nasty, but
he did make a recovery.

Nice action shot.

Leaning into the bends well.

Oh me and my big mouth!

He's leaning too far
into the bend

and his tires can't
provide enough friction,

causing him to low side,
before being run over.

Don't worry,
he was fine.

Ooh, that's a tight bend.

Well, hey, they made it!

[screams]

Oh, that's a shame.

Low side missed,
high side gained.

As his back wheel
hits the grass,

there's low friction
leading to a spin

and then a high side.

And then being run over.

What a nice day for a...

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

[Richard, off-screen]
High side in the country.

Cool, this is like
a computer game.

[tires screech]

[screams]

Although, I bet it hurts
more in real life.

Loss of friction at the wheel
followed by a sudden regain

of grip means massive
high side crash for him,

including a short
flight to the tarmac.

Now, I've done a bit of
car jumping in my time,

but luckily I'm inside the car
going from a ramp to a ramp,

and I've got my eyes shut.

But some people out there haven't quite
got the idea right

and have come up
with their own

absurdly dangerous version.

When done right,
it looks like this.

[Richard, off-screen]
But when it's done wrong,

it hurts a lot.

[man] Ow!

Safe to say this
is an extremely dangerous

and inadvisable thing to do,

but for the sake of scientific
knowledge alone, listen up.

[Richard, off-screen] First, he takes a
run up for optimum horizontal velocity.

Then, by jumping
with both feet,

he's able to convert as much
of that horizontal velocity

into vertical velocity
as possible.

Jumping from two feet

means he would take off
from the ground 25% faster

so he can get both legs clear of
the oncoming car,

avoiding a collision.

To jump as high as possible,
a person has to be running

at 70% of their
maximum speed.

Even so, car jumping is
still a recipe for disaster,

and here are just
some of the ingredients.

Approaching at an angle.

[man, off-screen] Oh!

[boy, off-screen] Do a flip.

[Richard, off-screen]
A stationary car.

[laughing]

And, lastly...

[tires screech]

Jumping with
a bike instead of legs.

[man] Oh no!

[Richard, off-screen] Right, now it's
time to put all that together.

He clearly
wasn't listening.

He doesn't convert
enough of his velocity

from horizontal to vertical.

A new windscreen is
the least of his worries.

This guy takes no run up
and jumps too late.

He has to generate all his vertical
velocity from the jump.

I don't know, but
might be worth wearing

shin guards next time.

A ladder will surely solve all the
vertical velocity problems.

[man, off-screen] Oh!

[Richard, off-screen] But
it counts for little

if there's a plank of wood
hanging out the back.

What was he thinking?

Basketball, one of the most
popular sports in the U.S.

Loads of skills, fast
reaction and, of course,

the very impressive
slam dunk.

Well, most of the time.

To pull off the perfect slam
dunk you need to see yourself

as a projectile
on a parabola.

I know that, that sounds
odd, but bear with me.

[Richard, off-screen] Once you jump,

your center of mass follows
a set trajectory,

a curved path
called a parabola.

This trajectory is set by your
speed and angle at takeoff.

If you hang on to the hoop,
your weight can cause a moment,

which is the turning
effect of a force.

A jump, a ball and a hoop,

put it all together and you've
mastered the slam dunk, right?

Easy, well, not exactly.

[Richard, off-screen] This guy's
parabola makes him

collide with the pole,

causing a pain
between his legs

and no points for his team.

[men laughing]

With the wrong parabola
set by his takeoff,

it's his face that
hits the rim not the ball.

Nice way of cheating.

[woman laughing]

But by holding onto the hoop,
his weight causes a moment

and the whole thing
crashes down on him.

He's the first to get the ball
through the hoop, though,

I'll give him that.

[woman laughs]

Another one using an object
to help with his trajectory,

but his cheating causes a moment as he
hangs on to the hoop,

and what a moment it was.

Ever heard of high lining?

It's an extreme and often
extremely dangerous sport

in which people walk across
a narrow springy line

suspended high
above the ground.

[Richard, off-screen] This is what it
looks like when you get it right.

And this is what it looks
like when you get it wrong.

[screaming]

And that's why
high liners wear a harness.

Whether you're
balancing on a high line,

a beam, or any
other thin object,

the science
is much the same.

[Richard, off-screen] If your weight,
which acts from your center of gravity,

does not go through the
pivot point at your feet,

it'll cause a rotation.

Make yourself wide.

Putting your arms out widens
the distribution of your mass,

meaning it's harder
for you to rotate.

If your line isn't taut,

it's possible to use your legs to
bring it back

underneath you
if you lose your balance.

But once your center of
mass has moved outside your

base of support, it's
very difficult to settle

at that central position again.

Right, before we ascend
to the perilous heights

of the high line,

how about starting
with something a little lower.

[Richard, off-screen] This is
about as low as you can get.

Don't forget what I
just said about regaining

that central position.

That low line was
actually quite high,

by the time he fell off it.

A touch higher now, but that
wider bar should make it

easier to keep his center of
mass over his base of support.

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

[Richard, off-screen] Although,
I suspect he's beginning

to regret that metal bar.

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

[Richard, off-screen] Another
wider base, but you do know

that ice is slippery, right?

[screams]

I'm surprised
you got that far.

[groans]

Another step up in
height now but it seems he

doesn't think
he needs a harness.

Well, think again.

He was using his arms to control his
center of mass well,

but once it was
outside his base of support,

it was nose in
the grass time.

And here it is,
the high line.

Good use of arms to
control his center of mass.

This is a master
class in high lining.

Oh, a little work needed
on your dismount, though.

Well, I think that's
more than enough stupidity

and science for now.

If you feel inclined to
have someone flip you over,

grind on a scooter, or
take a corner at speed,

well, don't and hopefully
we'll see you safe and sound

for the next
Science of Stupid.

[screams]

[man, off-screen] Oh!

[screaming]

[groaning]

[man, off-screen] Oh!