01x09 - Zip Lines Fails

[bunniefuu]

RICHARD: Stand by,
it's the Science of Stupid.

- [electricity crackling]
- [glass shatters]

- [alarm blares]
- [reading]

Yes, this is the show that combines
science and stupidity.

MAN: Oh, [bleep]!

RICHARD: Over the next half hour,
we'll witness the daring exploits

of some of science's
least-fortunate guinea pigs.

We'll explain what went wrong and why

by exploring the scientific principles
behind fluid dynamics...

flammability,

the vestibular system...

and our old friend, friction.

Science is an unforgiving mistress.

WOMAN: Are you [bleep] kidding me?

RICHARD: Treat her with respect...

or it'll all end in tears.

So don't try any of this at home,

or anywhere else for that matter.

Watch out.

It's the Science of Stupid.

[electricity crackling]

[glass shatters]

On this show, we'll see what happens
when centripetal force

meets an external force.

MAN: Oh.

RICHARD: The consequences
of mocking gravity.

[laughter]

And the effects of inertia...

it's smashing.

But first, this.

[glass shatters]

[electricity crackles]

Gymnastics can be dangerous.

That's why people do it inside
with lots of lovely safety mats.

But that's what I thought
until I saw this.

Yes, parkour is the art of running around
an urban landscape

and can be particularly hazardous
where height is involved.

Somersaults, backflips, the spinny things.

And one of my personal favorites,
the cat leap,

a technique for jumping across a gap
to a vertical surface

and pulling yourself up by your hands.

It is actually inspired
by the way a cat can jump,

but not by the way it can fall.

[man laughs]

OK, folks, remember
cats supposedly have nine lives.

Humans only have one.

To get it right, the technique
of the parkour expert needs to be spot-on,

and here's some science to show how.

To get maximum velocity on takeoff,

he throws his arms forwards
in a swinging movement on the jump.

This creates additional downward force
on the hip joint,

giving over 20% more distance,

but the real skill is in the landing.

He swings his legs around
to cushion the force of hitting the wall,

his tendons act like springs,

absorbing the shock of impact
to prevent hitting the wall

with too much force to hold on.

But these urban athletes must first
remember to get their takeoff right.

Using the correct technique,

the maximum pushing force
of a jump at takeoff

is over 750 pounds,

enough to get a grizzly bear
off the ground.

Imagine what that would do to a cat.

Let's see those g*ns
in action then, fella.

Yeah, nice arm work, but for big jumps

he'll need a run up to boost his velocity

before his arms
add that extra 20% distance.

He's got it.

[cat meows]

He hasn't.

But it's pointless knowing how to takeoff

without knowing how to use
those spring-like legs to land properly.

It's all about timing.

MAN: Yeah, Casper, go.

Oh, [bleep]!

RICHARD: Just ask Casper.
Casper brought his feet up too late,

preventing his legs
from acting like springs

and absorbing the impact,

meaning he hits the wall
with too much force

and falls like a ton of bricks.

- MAN: Yeah!
- RICHARD: Don't worry, he's fine.

So he wants to bring his feet up
nice and early, right?

Not quite.

He brings his legs up too early
and the absorbed energy released

from those spring-like muscles
simple bounces him off the wall

like a tennis ball.

After the theory,
all it takes is practice.

And a lot of blood, sweat and tears.

But mainly blood.

And when it's finally nailed...

a good exit strategy is vital.

MAN: Ahh!

[electricity crackles]

Surely the only real danger
of being towed through the water by a boat

is that sooner or later
you might get a bit wet,

but that's half the fun,
so where's the harm?

[woman screams]

Well, it's there.

[screaming]

There.

And there.

Well, aside from using your eyes

and looking where you're going,

there is a little scientific
know-how on towing

that might save you
losing control of your mates

and mashing them into a pulp.

Here it is.

When a boat towing an object turns,

the object turns, too,
due to centripetal force

created by the tension in the tow rope.

The object being towed
has to travel further than the boat

within the same time,

and so will travel faster than the boat.

During a 360-degree turn,
the force of the whip is so large

it can actually triple the speed
of the object

compared to the boat.

If that boat is traveling
at 20 miles per hour,

these chaps could be doing up to 60.

Here's a wake boarder
enjoying centripetal force.

Remember as you get towed around corners,

you're likely to be going a lot faster.

At this point, the only thing
likely to stop you

is an external force...

from something like a bridge.

Now, let's see how those forces work
on dry land.

Much the same way...

- MAN 1: Oh!
- MAN 2: Oh, [bleep] [bleep]!

RICHARD: ...with much the same results.

MAN: Oh!

- MAN 1: Oh!
- MAN 2: Oh!

OK, so what science
is trying to tell us

is to take it easy on your corners

and only hammer it on the straights.

Yeah, but it's not quite
as simple as that.

When the thing you're being towed about on

is a large inflatable object, like a tube,

you can encounter
another problem-- Taking off.

MAN: Oh, lovely! Yeah!

Oh! Oh! Oh, [bleep]! Oh, [bleep]!

RICHARD: Great at taking off,
rubbish at actually flying.

Remember that.
Well, you--you probably will.

- Yeah.
- MAN: [bleep]!

RICHARD: Tubes have similar
aerodynamics to airplane wings,

with curved edges and a flattish profile,

so when the underside of the tube lifts up

the air hitting it creates pressure,

pushing it further upwards.

An airplane has wings
to keep it stable in the air.

MAN: Oh, [bleep]!

RICHARD: An inflatable tube does not.

So next time someone offers you
a tow-about in the water,

remember that things could get fast.

Might even fly...

which is fun...

if you're partial to a bit of whiplash.

- [electricity crackles]
- [metallic thud]

Can you guess what scientific law

these sporty youths
are about to demonstrate?

[glass shatters]

WOMAN: Oh, my God.

RICHARD: Did you guess the scientific law
we're about to see?

It's Newton's third law.

With every force
there's an equal but opposite force.

The harder you hit a car,

the harder it hits you.

- [electricity crackling]
- [creaking]

Can you guess what the most dangerous
consumer product

in the United States is?

[drumroll]

No?

Here's a clue.

MAN: Whoa. Oh, Jesus.

It's quads.

In the right place,
and with proper skills and experience,

all-terrain vehicles
are designed to give maximum fun,

yet tend to be a bit unstable
for performing stunts.

A quad's center of gravity is very high

relative to its narrow wheelbase.

This means that when performing maneuvers,

the center of gravity
has a greater tendency

to move outside of the wheelbase

and the quad can tip over.

Quads often have ultra-springy suspension,

and typically inadequate
shock absorption for big jumps,

meaning that when they land,
the springs release all the energy

absorbed in the impact,
causing them to buck.

- [man screams]
- [crash]

But first things first, let's get to grips

with that dodgy center of gravity.

Use your body weight
to correct the center of gravity.

Not like that.

When cornering,

shift your weight forwards
and into the turn.

Sidesaddle doesn't work,
and let's face it,

it is a bit uncomfortable,

and what's really uncomfortable
is a 450-pound quad

piling in to you at 25 miles an hour.

What about going uphill?

Is that an issue?

Yes. At least it's never wise
to attack too steep a hill.

A standard quad is designed
to handle uphill slopes

of 45 degrees without a driver.

The problem is, if you actually
want to sit on your quad,

then you're raising
your center of gravity

to a precarious level.

There's the proof.

And that's confirmation.

On an uphill gradient,
keep your weight forward

to keep that center of gravity
within the wheelbase.

But not too close the wheelbase.

Right, so now you know why
having a high center of gravity

can be a problem.

So you might want to think carefully
before attempting a jump.

WOMAN: Oh, my God,
he's gonna crash!

RICHARD: Hey, that's a plot spoiler.

WOMAN [screams]: Oh, my [bleep]!

RICHARD: OK, you don't need
science to tell you

that you shouldn't jump into a cliff.

But there is somewhere science can help.

Remember what I said
about springy suspension?

Well, there you go.

When jumping, you need to stand up
to use your legs like shock absorbers,

as well as adjusting the center of gravity

by keeping your body weight back.

I said back.

And do watch out for the wall.

- [electricity crackling]
- [creaks]

Now for the ultimate battle
between man and beast.

Saddle up partners, it's rodeo.

The idea is to ride
a bucking horse or bull

for at least eight seconds,
holding on with just one hand.

It is easier said than done,

as animals like these can be
dangerously unpredictable.

[groans]

[moos]

[man laughs]

It's not just about holding on.

There is a bit of science, too,
so listen up, y'all.

What?

When a rodeo bull or horse bucks,

the rider's body
is subjected to tremendous force.

For a bareback rider,
this could mean accelerations

of up to 46 G's,

five times that of
a jet pilot in training.

When the animal stops
or changes direction,

the rider's inertia keeps them traveling
in the original direction,

which can throw them off.

Professional rodeo riders
overcome the effects of inertia

by using their center of mass

to counteract the bucking forces
acting on them,

pushing their body backwards

when the animal kicks back
and forwards when it rears up.

But even for pros, this is no mean feat.

If you're looking
for a demonstration of the science,

everything's happening a bit fast
with a pro rider.

But with the aid
of some intrepid amateurs,

and a mechanical bull,

we can see the effects of inertia
in a more controlled environment.

Here's test subject one. Are you ready?

I'm ready!

RICHARD: Good. OK, if you're sure.

Let's break that down.

Here's the kicking force.

Here's the change of direction.

Here's inertia keeping her moving forwards

and here's the nose job.

Inertia isn't a force.

In fact, it's a property that's present
in everything and everyone, including him.

And her.

And him.

Oh, a somersault, well done.

This lady's about to demonstrate

the relationship between
inertia and mass.

[people scream]

It's proportional,
so once the bull gets her moving,

it's almost impossible for her to stop.

So what have we learnt?

Well, riding rodeo will subject you
to the meanest side of inertia.

Fail to use your body mass
to counteract this

and you're gonna wind up eating dirt.

Tasty.

- [electricity crackles]
- [creaks]

I've always dreamt
of having special powers

like a superhero,
so when I heard about Batmanning,

I thought, "This is gonna be exciting."

I was wrong, it's not.

It's basically hanging about
by your feet.

OK, so it's not exciting
when it's done right.

Right. I'm so disappointed
that I missed out on planking

that I'm gonna give Batmanning a go
just for you, Natalie.

RICHARD: Look away, Natalie.

I've got a feeling he hasn't considered
the gravity of the situation.

[grunting]

[groans]

Do you think that's Natalie?

Let's hope her first aid
skills are up to scratch.

- [groans]
- [dog barking]

Batmanning can look boring,

but in the wrong place can be
incredibly hazardous,

so at least pay attention to the science.

Batmanning relies on
keeping the ankles tensed

as tightly as possible

and adhering to the principles
of leverage.

Feet balanced on the door edge

are effectively a lever on a pivot.

Leverage dictates
that the greater the distance

between the pivot point
and the force applied to the lever,

the less force it takes
to turn that lever.

For Batmanning, that means ankles
are as close to the door as possible.

Double the distance
from ankles to door edge

and it's double the tendency
to rotate and fall off.

Batmanning.

If you want my opinion,
don't bother, it's just plain silly.

But in the world of science,
we would know nothing

without the work of our great pioneers,

and here they are.

Remember, it's all about
keeping those ankles tense

and the principles of leverage.

[woman chuckling]

Her ankles may be weak,

but at least she now
has the unique ability

to look directly behind herself.

Full marks here
for getting the technique right,

but she does have to maintain it.

[women laughing]

WOMAN: Oh, my gosh.

RICHARD: Hmm. Remember, once up,

keeping those ankles tense
is, uh, pivotal.

This qualifies as a wild night out
in Lapland.

[man laughing]

Two problems here,
balancing on the toes

combined with consumption of mince pies

equals too much force on the ankles.

- [electricity crackles]
- [creaks]

[clattering]

Riding a motorbike safely is important

if you're riding a motorbike.

Then if you are, you need
the right equipment and training

so motorbike jumps
seem like sheer madness,

but they do say insanity
is close to genius,

so perhaps we shouldn't be too judgmental.

Or perhaps we should.

There are some common sense rules.

A bike that actually fits.

A regularly maintained bike.

And no performing stunts in a forest.

But there's also some science,

so what do you need
to perform the perfect jump?

Two wheels, a big motor
and very little common sense.

Well, there's more to it than that.

It's all about speed and angles.

The first thing you'll need
is adequate speed.

Speed equals distance over time,
so the further you jump,

the more speed you'll need to achieve it.

The next ingredient
is the angle of launch.

Adjust the takeoff angle
to determine the desired trajectory.

Balancing time in the air
created by height

and forward movement
gives the right direction.

They say the road to success
is paved with failures,

and that's just as well
because we've got plenty.

OK, so first things first.

Getting up to an adequate speed.

That was inadequate.

For maximum speed open up that throttle...

[screams]

...especially if you're an adult
on a child's bike.

Once he's up to speed
and wants to do some tricks,

a really steep angle
directs his velocity skywards.

And what goes up...

Oh, nice recovery.

How many degrees is that? Who knows?

But letting go isn't always
the answer if you're not sure.

And of course, angle of landing
is just as important

as angle of takeoff.

MAN: Oh! [bleep]!

RICHARD: To minimize impact,

the difference between
your angle of descent, this,

and the angle of landing surface,

must be as low as possible,
just like that.

But not that.

[man yells]

Nor that.

Had he landed with his bike,

all the reactionary force from the ramp

would have been concentrated
on just the back wheel,

which could have meant
an even more painful landing.

And whatever happens,
it's best to land on something forgiving.

- [thudding]
- Like a friend.

[glass shatters]

[electricity crackling]

That's about as much senseless violence
as I can take for now.

They do say no pain, no gain,

and I hope you've gained
some scientific take-home from this.

To skip on the pain,
just refrain from repeating

anything you've just seen,

I mean anything literally, at all.

[woman laughing]

- MAN 1: Oh!
- MAN 2: Oh! Oh!

WOMAN: [screams] Oh, my God!

- [moos]
- [man groans]

[man yells]