01x14 - Ring of Fire

[bunniefuu]

RICHARD: Stand by.
It's the Science of Stupid.

[electricity crackling]

[reading]

[alarm blares]

Yes. This is the show
that hits science right where it hurts...

with the stupid stick...

and reveals the results
of our favorite amateur experiments.

The next half hour

is a no-holds-barred battery of friction,

Newton's laws,

and angular momentum.

Find out the hard way
if you try to break the laws of science,

they'll break you.

So people, remember,

scientific knowledge shouldn't
come from a leap of faith...

[screaming]

...but from cold, hard fact.

Now strap on the safety goggles.

It's the Science of Stupid.

- [electricity crackling]
- [glass shatter]

On this show, we'll see how
gravity spoils your long jump,

how the biology of your inner ear
can get you into a spin,

and how jet propulsion
can ruin your picnic.

[glass shatters]

But first, this.

[electricity crackling]

For some people, just climbing up a cliff
is not exciting enough.

Getting down quickly is the fun part.

It's known as abseiling or rappelling.

But even with
the right equipment and training,

it can be fatal.

MAN 1: Let's go!

RICHARD: To learn how to do it right,

what could be better
than some military-grade training.

MAN 2: Yeah!

RICHARD: Yeah!

Oh.

And it all looked so easy
in the recruitment video, didn't it?

MAN 2: You all right?

But if you're still in love with the idea

that broken bones
mend faster than broken hearts,

then you need to know how to avoid
getting a face full of concrete.

In rappelling, or abseiling,
gravity pulls your body down,

and friction in the rope
stops you falling.

To increase friction, the climbing rope

is usually threaded around
a metal friction control device.

This works as a break.

The effect of winding is exponential,

which means the force you need to apply

could be under a tenth
of your body weight.

Adjust the friction by changing
the angle of the rope through the device.

Slacken the rope to descend,
and apply friction to keep still.

Get this wrong,
and you're heading for a fall.

[man screaming]

Yes. Unlike in relationships,
friction is a positive thing

when you're climbing.

You've heard the expression,
"Give him enough rope."

MAN 1: Whoa!

Oh, gosh! [bleep]

RICHARD: When abseiling,
you are supposed to tie a knot at the end,

in case you find yourself
with less rope than you need.

MAN 2: Oh, gosh! [bleep]

MAN 3:
Did you forget that was short?

[laughter]

RICHARD: It's possible, but not advisable,
to abseil without a friction device.

He's securing one end of the rope
around the balcony,

and wrapping the other end around himself.

This could be dangerous.

MAN 1: Go on, let it go!

Oh!

MAN 2: Oh, oh!

RICHARD: It doesn't matter how many times
he winds it around anything...

if the rope isn't strong enough.

MAN 2: Russ, you alright bruv?

RICHARD: Luckily, he was.

Russ walked away... eventually.

The British and Australians
call it abseiling.

In America, it's known as rappelling.

And that's known
as jumping out of a window

and smashing into a wall.

MAN 1: Ow!

RICHARD: Did someone say, "Pendulum"?

MAN 2:
Do you need an ambulance?

MAN 1: No, I'm alright.

RICHARD: Ah, the military.
They'll know how to do it.

- MAN: Ugh!
- RICHARD: Oh.

Maybe there's a manual they haven't read.

Abseiling is a bit like a controlled fall
using friction as a break.

[indistinct shouting]

Without friction, it's just a fall.

MAN: Ninety foot.
Thalehaha Falls, Rubio Canyon.

RICHARD: And his buddy is about
to experience most of that drop

faster than he was expecting.

MAN: Oh! [bleep] Matt!

[bleep]! Holy [bleep]!

RICHARD: When this climber slips,

he instinctively lets go
of his brake line.

Falling just 15 feet can have
an impact force of about three tons.

MAN: Matt!

RICHARD: He's lucky to walk away
with nothing but bruises.

- [electricity crackling]
- [metallic squeak]

I think we're all agreed
that walls are unsuitable for running on.

What with them
generally being vertical and everything.

Well, some people just have to push
the envelope, don't they?

MAN: Uh-oh.

RICHARD: Next time,
just use the stairs like a normal person.

If that's not put you off,

then pay attention to the science
before you go near a wall.

Friction is the successful
wall runners' friend.

A fast run up speed maximizes friction.

The aim is to generate enough friction

to push up against the force of gravity,
and grip the wall.

Running with his body at near 45 degrees,
stops him falling over or sliding down.

He springs off at the end,
and his momentum keeps him going.

Get this right, and you'll look
pretty cool as you run along a wall.

Get it wrong,
and you'll look like your dad.

[screams, laughter]

Oh, it is your dad!

MAN: Move!

RICHARD: Yeah, it really does help
if he hits the target.

Wall running can be vertical too,

providing the wall doesn't fall down.

He must hit the wall,

but not with his head.

MAN: Ahh.

Turning a wall run
into a successful wall flip

doesn't have to be painful,

But it often is.

It doesn't matter if you take
one step, two, or more,

the principle is the same.
You need friction.

First, he runs at the wall with speed,
planting his foot firmly on the wall.

That speed gives him
the friction he needs to drive up.

He pushes outwards to add angular momentum
and avoid hitting the wall as he spins,

then lands on his feet.

So, all you need is speed and agility.

Easy. Isn't it?

Oh, yeah. I forgot to mention,

in order to complete
your rotation in time, you have to tuck.

A lack of speed means
a lack of friction on his foot,

so he only rotates enough to land...

on his head.

If the target isn't securely fixed,

you'll have issues creating enough force
to change direction.

It's even harder
if you're trying to flip forward.

MAN: Oh. [laughs]

RICHARD: He's just planted
his foot too high on the wall.

His body's angled like this,

not this.

So he can't push himself any higher

and loses the air time
needed for rotation.

So before he can tuck,
gravity slams his body

onto the pavement.

[electricity crackling]

[metallic squeak]

[metallic thud]

What scientific principle was overlooked
by these enthusiastic drag racers?

[engine revs]

- [glass shatters]
- [electricity crackling]

The scientific principle

overlooked by the driver
of this dragster is...

[engine revs]

...torque.

It's the engine's ability
to rotate the wheels.

The driving force of a drag car like this
generates a massive amount of torque.

But deliver too much torque too quickly,

and the whole car rotates
and over it goes.

I like things that are clearly labeled.

Take the long jump.
Does what it says on the tin.

Jump a long way.

What's hard about that?

[woman screams]

[laughter]

The current world record
for long jump is over 29 feet

held by the USA's Mike Powell,

and has now stood for over 22 years.

Here's the science behind his leap
into the record books.

A great long jump
needs horizontal velocity.

Every extra two miles an hour
can get you three feet further.

The best long jumpers
reach over 20 miles an hour

and take off at an angle
close to 21 degrees.

They follow an arc
up to six feet high at its peak,

and land extending the legs
to help maximize distance.

It also helps if you've got
a nice soft surface to land on.

Yes, a successful long jumper
must have great coordination and timing.

Sadly, these attributes
rarely go hand in hand.

Remember, speed, 20 miles an hour.
Jump angle, 21 degrees.

MAN: Whoo!

RICHARD: But actually jumping
is, of course, crucial.

MAN: Come on, Mitch! Power!

RICHARD: Speed.

Angle.

[man groaning]

I bet the USA's Mike Powell
doesn't land like that.

An impact with over 600 pounds of force.

He's trying to combine long jump,
high jump and hurdling.

And fails in all three.

If you don't want
to crash land on the floor,

then water can soften the impact.

Aw, who put that there?

All you need is the right speed,

and the right angle of takeoff.

You won't see that at the Olympics, ever.

Now, here's someone with confidence.

Maximum run up, good angle of takeoff.

Ah, that's why those pool signs
say no running.

- [electricity crackling]
- [creaks]

They say a healthy life
is all about balance, and I agree.

But I'm not talking about
a good diet and lots of exercise.

I'm talking about simply keeping upright.

What better way
to end a night out with the boys?

[laughter]

Yes, a humorous study of dizziness.

[laughter]

The human body
has developed systems

to tell it where it is
and how it's moving.

I call mine a sat nav.

Dizziness is caused when a part
of the brain called the cerebellum

gets confused as it processes information

from three of the body's
major sense systems,

the eyes, muscles, and the inner ear,

where a fluid called endolymph
moves in response to gravity

and acceleration.

It's the body's spirit level.

To avoid getting dizzy,

ballet dancers lock their gaze
for as long as possible

on a fixed point before moving,

a technique called spotting.

The eyes suppress
the dizzying signals from the ears.

With practice, the balancing part
of their cerebellum can shrink,

minimizing the dizzying effect.

Some people enjoy
all manner of fairground rides

that pick them up and spin them round
without getting the least bit dizzy.

But we're more interested
in people at the opposite end

of the dizziness scale.

This chap is managing
to keep his head up straight.

Is he contemplating a future in ballet?

Well, he certainly
hasn't got much of a future in football.

You can tell she's trying
to minimize dizziness by spotting,

like a ballerina.

[laughter]

And now she's falling...

like a tree.

When you bend over,

spinning has a greater effect
on the endolymph in your inner ears,

and the dizzier you get.

MAN: Oh, my God!

[laughter]

RICHARD: Nicely demonstrated.

MEN: Three, four...

RICHARD: Spinning the fluid
in your inner ears just makes you dizzy.

It doesn't actually make
other people appear green.

But getting hit there just might.

Feet off the ground, and no spotting.

How will her cerebellum fair?

GIRL: Oh!

RICHARD: Badly.

After spinning, the inner ear and brain
take time to return to equilibrium,

making your cerebellum think you're going
in the opposite direction.

You try to compensate, but instead...

you fall over.

- [glass shatters]
- [electricity crackling]

Medieval knights.
They were real men.

They may be consigned
to the history books now,

but some brave traditionalists

are keeping the spirit
of the Middle Ages alive.

Yes, it's at times like these
I feel closest to the heroic deeds

of past times.

Horses, spikes, and speed.

Real jousting can be deadly.

But any kind of jousting
depends on impact force and aim.

The greater the combined mass
of horse and rider,

and the greater their speed,

the greater the impact force
from the lance.

With 1,500 pounds moving
at 20 miles an hour,

the impact exceeds 1,000 pounds of force,

meaning a defeated jouster
briefly experiences more g's

than an astronaut during takeoff.

By hitting near the shoulder,
it's easier to knock your opponent down,

because the torque generated
makes him twist and fall.

These days, horses and armor are absent
from most suburban homes

and we're poorer for it in my opinion.

But, thankfully, some enthusiasts
have re-purposed

medieval jousting for modern-day pleasure.

It's a day out from the office,

and these desk jockeys
have brought their chairs.

They've got the armor,

they've got the speed...

but the torque on those wobbly chairs
spins them quickly into the dirt.

Swivel on that, Lancelot.

A direct strike on the shoulder...

sends this North Carolina knight
butt first onto ye olde black-top.

Proper jousting depends on mass and speed
to create impact force.

You can't get much speed up on a unicycle,

but you don't need so much force
to knock your opponent down.

Those chariots
are not as heavy as a horse.

And a hockey stick
can be ten times lighter than a lance,

but with impact force
and torque still playing a role,

- someone's going over.
- MAN: Ow!

RICHARD: Adding speed increases the force
experienced by your opponent.

The force is with him.

No powerful horse, and no heavy lance,

but both jousters
feel the same impact force and rebound.

That's Newton's third law.

To maximize your opponent's rebound,

you need more weight to send them down.

However you make your approach,

as long as there's a direct hit
near the shoulder,

torque will twist your opponent
to the ground.

[laughter]

MAN: The mother [bleep] gallon joust.

RICHARD: Remember,
the combined force of the rider's weight,

a trusty steed and his weapon of choice,

all goes into the impact.

MAN: Ahhh!

RICHARD: But don't milk it. [chuckles]

- [crowd groans]
- Oh, sorry.

- [electricity crackling]
- [creaks]

India recently launched a rocket to Mars
costing 45 million pounds.

That's cheap for a rocket,
but still a bit steep for most of us.

Luckily, in garages around the world,

enthusiasts are finding
cheaper and less intelligent ways

to launch themselves into the air.

Time to return Buzz Lightyear
to demo mode.

The problem with jet packs
is balancing power and control.

Jet power depends on thrust
to overcome weight and generate motion.

High speed ejection of fluid
generates equal momentum

in the opposite direction.

Yep, you guessed it, Newton's third law.

The bigger the payload,
the more thrust is needed for lift off.

Jet packs need to be both
powerful enough and light enough

to achieve lift off.

They need a high thrust-to-weight ratio.

Thrust is the problem.

Too much or too little, and you end up
looking less like a space ranger,

and more like a space monkey.

The operating pressure
of a fire extinguisher is 850 psi.

Not enough to get airborne...

yet great going forward.

Thrust wasn't the problem here.

It was tiny wheels.

Even the smallest bump flips the cart.

Each of the space shuttle boosters

generated 3.3 million pounds
of thrust at launch.

In comparison,
the thrust from a leaf blower

doesn't seem very impressive.

But it's more than enough
to make you dizzy.

So it's back to the drawing board.

Well, that's not lift off.

But it is a good demonstration
of why leaf blowers

shouldn't be used indoors.

Instead of rocket fuel,

this jet uses water under high pressure
to generate thrust.

Same scientific principle
and potential for embarrassment.

A separate fuel system vastly improves
your thrust-to-weight ratio.

[laughter]

More than 700 pounds of thrust

can propel the pilot
almost 30 feet into the air

at speeds of up to 22 miles an hour.

And even faster on the way down.

Great technology,
but it still relies on piloting skill.

I don't know, maybe he should have
kept his hands on the controls?

Jet skis use exactly the same process,
ejecting fluid to create thrust.

Quite a lot of thrust.

Using water, they've got
marvelous thrust-to-weight ratio...

until they take off.

Then they have a rubbish
thrust-to-weight ratio.

But a heavy hand on the throttle
can easily give too much thrust...

which can seriously ruin your day.

Or the garden furniture.

- [glass shatters]
- [electricity crackling]

Others may have been battered and bruised,

but we've arrived safely
at the end of our journey.

Shall we do a last little check
that everything's intact?

That swelling could just be
the souvenir of an extra lump of knowledge

from watching the Science of Stupid.

[lively fiddle music playing]

[man groaning]

[indistinct shouting]