03x04 - Cliff Diving, Sledge Hammer and Scooters

[bunniefuu]

[Richard]
This is the Science of Stupid.

Yes, this is the show
that puts the "fizz"...

-[loud bang]
-...into physics.

It's a c*ck of scientific suffering.

One part science,

two parts stupid.

Shaken and stirred,

poured over ice,

it's best enjoyed
with scientific principles...

like conservation of momentum...

-[yelling]
-[crashing]

...troublesome old gravity...

[man]
Whoa!

[man]
And reaction force.

[boy]
Aah!

[man]
Mingle science with mayhem,

and you've got yourself a mighty mixture.

[shouts]

So stand back.

It's the Science of Stupid.

[electricity crackling]

[shattering]

In this show, we'll explore
the ups and downs

of kinetic energy.

Angular velocity:
Can you have too much?

And the scientific principle
behind lift...

[crashing]

Or the lack of it.

But first, this.

[glass shattering]

[electricity crackling]

[shattering]

For those who don't ride a motorbike,

the only way to appreciate
their visceral thrill

is to ride as a passenger.

But there's no thrills
without the potential

for some pain-inducing spills,

so safety is paramount.

It's a matter of wearing the right gear

and using one's head.

-[man yelling]
-[thuds]

Yeah, that's not what I meant

by "using one's head."

-[man yelling]
-[thuds]

For those compelled to show
their passenger their riding prowess,

something closer to terra firma
might be a little safer,

like this, the tandem wheelie.

It's just like a regular wheelie...

-[crashing]
-[man] Aah!

[man]
...but a lot harder to pull off.

[man]
Aah!

[man]
Pulling a wheelie on a motorcycle

results in a supercharged unicycle.

Add a girlfriend to the back,

and it's a wobbly
supercharged unicycle.

What could possibly go wrong?

Let's see the science.

[electronic music]

To initiate the wheelie,

the rider rapidly accelerates,

creating torque around the rear wheel

and lifting the front.

To stay balanced,
both rider and passenger

ensure their combined center of mass

remains over the base of support.

When the front wheel returns to Earth,

they both need to hold on tight.

The sudden downward motion
creates angular momentum,

which could unseat
an unbalanced rider.

To pull off the tandem wheelie,

both rider and passenger
have to balance in unison.

If either mess up,
they're both going down.

No such problem for this couple.

Perfectly balanced,
they look totally relaxed

as they rocket up the runway...

[crashing]

But now less so.

The front of the bike lifted too high,

making the angle too steep
for the passenger to hold on.

And as she was clinging
onto the rider,

he went flying, too.

[country music playing]

[crashing]

Some wheelies aren't on purpose.

This couple are in a drag race.

[engine revving]

There, that is a drag.

The rider accelerated too hard,

sending the bike's weight
to an already heavy rear end,

and it wheelied out of control.

But thanks to their momentum,
both rider and passenger

finished the sprint on their bottoms.

And they still won.

Well done.

Having had their fill
of tandem wheelie-ing,

it's time for the rider
to get the front wheel

back down to Earth,

and that's when the fun really begins.

[upbeat music playing]

The riders up ahead

fancy a cheeky wheelie on the freeway.

It's not the best place
for a lie-down, really.

I think it's time we made way
for the pros.

What these two don't know
about center of mass

isn't worth--

-[woman screams]
-Oh, good grief!

Traveling at over 40 miles an hour,

when the front wheel hit the ground,

angular momentum rotated
the passenger forwards,

hitting the ground with a force

equal to nearly eight times her weight.

[woman yells]

That may have hurt.

[man, off-screen]
So what happened?

[woman]
I was a dumb ****.

Rolled over this bar.

It happens.

It was fun, more or less.

[man]
"Fun more or less"?

[woman yells]

I'm thinking less.

[electricity crackling]

[metal clanging]

If you asked me to while away
a few hours with friends,

it would probably involve
stimulating conversation,

a bottle of something French,

and a spectacular selection of cheese.

Not trampolining.

But team trampolining is all the rage

amongst high-flying ladies.

[screaming]

And groups of lads think
it's flipping good fun, too...

Apart from him. He doesn't.

[boy screams]

One person on a trampoline
is fairly simple to understand.

Add a few more, and things
get a lot more complex.

Time for some science.

As a trampoline stretches,

it stores elastic potential energy.

When it springs back,
the elastic potential energy

is converted into kinetic energy.

Two people jumping together

produce twice the kinetic energy,

and if she lands a fraction
of second before him,

some energy is transferred
from her to him,

resulting in a super strength bounce.

Trampolines will spend months
sitting in our gardens,

so before you and your bouncing
buddies jump aboard,

you'll want to check your equipment

for signs of fatigue.

Like corroded springs.

[man]
Oh!

[man]
And weather-worn fabric.

-[ripping]
-[boy shouts]

Particularly if you're a bigger kid.

[boy]
Aah!

[man]
Oh, that's torn it.

The jump mat was stretched
beyond its yield strength,

resulting in one broken trampoline...

[boy]
Aah!

[man]
And one very broken trampolinist.

[laughter]

Trampolines are soft and bouncy.

What harm can there be

in the occasional mega-strength
super bounce?

As long as you know
the double bounce is coming.

[thuds]

The chap in the red T-shirt

cheekily stamps on the trampoline.

This adds kinetic oomph
to his chum's bounce...

[thuds]

...sending him flying.

[laughter]

No trampoline here...

[boy groaning]

But the same high-flying science.

By transferring the kinetic energy

of a trio of free-falling lads,

the catapulted kid landed
with the equivalent force

of nearly twice his own body weight.

It was a nice somersault.

It's just a shame about the landing.

[boy]
My face is dead.

[electricity crackling]

[metal clanging]

[man]
This BMXer is going to attempt

a midair bike-to-bike transfer.

[man, off-screen]
Same spot?

[man]
But what scientific principle

is he about to encounter?

[glass shattering]

[electricity crackling]

[shattering]

[man, off-screen]
Here we go!

[man] Have you worked out
the scientific principle

that's going to affect this BMXer's stunt?

[shrieks]

[crashing]

That's right, it was
Newton's Second Law of Motion.

[man, off-screen]
Hey, you're an animal!

[man]
An animal with a really sore bottom.

He may have had the equivalent
momentum of a baby elephant

traveling at over 20 miles an hour,

but he didn't transfer enough
of it to the second bike

to allow it to accelerate

beneath his rapidly moving bottom.

In other words,
he was trying to do this.

Bingo!

[man, off-screen]
Bravo!

[electricity crackling]

[metal creaking]

[crumbling]

[man]
Catching. It's as simple as

holding out your hands and...

-Oh... One day.
-[shattering]

To me, the world of ball sports...

-[man] Oh!
-[laughing]

[man]
...is just a world of pain.

-[man] Aah!
-[man, off-screen] Oh, no!

[man]
He doesn't like ba*ls either.

Thankfully, science is here
to offer a helping hand.

When attempting to catch a ball,

we simply don't have the time
to calculate

where the ball is going to land.

Instead, we use
a catchy-sounding process

called "linear optical trajectory."

For a successful catch,

the fielder needs to track
the ball's trajectory

and reduce the effect of its momentum.

He does this by pulling his hands down

during the catch, increasing the time

over which the ball loses momentum,

thereby reducing the force.

If you keep your eyes on the ball

and get yourself in the right position,

you can pull off mind-boggling catches.

No matter which way up you are.

[splashing]

Hope he can swim.

But keeping your eye on the ball

does have its drawbacks.

Oh, nice catch, though.

Take your eyes off the ball,

and you're asking for trouble.

[grunts]

The basketball
may have been moving slower

than a speeding baseball,

but its greater mass means
that it will have hurt...

a lot.

[grunts]

Anyone who has ever caught
a speeding cricket ball

knows that they can really sting.

So when catching a ball,
it's important to remember

to pull your hands back
to reduce the force.

This is made harder
with irregular-shaped ba*ls.

The ball's momentum here

was transferred to her face.

[upbeat music playing]

And then the ground.

You can catch all sorts
of things at music festivals,

like drinks!

By moving his hand in the direction

of the flying cup,
he reduced its momentum.

The liquid still had momentum,

so some sloshed out,

but he did manage to save a mouthful.

I really hope that's what he thinks it is.

[man, off-screen]
Yip skiddly do!

[man]
Couldn't have put it better myself.

[man, off-screen] He needs a beer!
Throw him a beer!

[man] Time for some more
beverage hurling,

but this fella's not daft.

He wants an unopened can.

Genius!

[man, off-screen]
Oh!

[man]
The can was coming in too fast,

and he didn't manage
to slow its momentum.

Well, he did...

[man, off-screen]
Oh!

[man]
But with his head.

-[man 1, off-screen] Oh!
-[man 2] Oh. Ooh!

[splashing]

[school bell rings]

[clattering]

[bubbling and sizzling]

[man] Now it's time
for today's science lesson,

so pay attention, class,

because we're about to learn
a groundbreaking principle.

Hands up. Who can tell me
what this winged wonder

has in common with airborne bonnets...

...and flying saucers?

-[thwacks]
-[groans]

That's right, they're all examples

of Bernoulli's principle

of fluid dynamics and pressure.

Or put simply,

today, class,
we're having a flying lesson.

[laughter]

All right, so turning to page 12,

Bernoulli's principle states

that the faster a fluid,
like air, is flowing,

the lower its pressure will be.

To take off, a plane
has to create enough lift

to overcome the force of its weight.

Its wings are designed
to make air travel faster

across the top surface.

This creates an area of lower pressure

above the wing, contributing to lift.

Once airborne, control surfaces
on the wings and tail

allow the pilot to change the flow of air

and alter direction and altitude.

To land, the pilot
eases back on the throttle

and reduces airspeed,

using the flaps on the wings
to maintain lift

and avoid a stall.

Right, that was the theory
behind taking off,

maneuvering, and landing.

Now it's time to put
your knowhow to the test.

First up, do you know
what these aviation pioneers

are lacking in their attempt to take off?

They've got wings, lots of them,

but without speed, they can't build up

a large enough pressure difference

to generate sufficient lift.

To generate speed,
you need a runway.

[whirring]

Not a picnic bench.

This car has got lots of speed...

[tires skidding]

[crashing]

But now it has less.

A racecar uses Bernoulli's principle

to generate downwards lift,

keeping it pressed to the track.

But as this car spun out of control

and damaged its structure,

that downwards force disappeared,

and the front lifted up.

[crashing]

Ooh, don't worry, mate.

Bit of polish, I reckon that'll clean up.

Question two: A plane has
movable surfaces on its wings,

but what are they for?

By adjusting the speed
flowing over each wing,

a pilot can accurately control
its direction, and--

-ooh, watch out!
- [man] Aah!

Aah!

[man]
Paragliders don't have control surfaces.

You steer them by pulling ropes

attached to the canopy.

It's not quite as responsive.

A powered paraglider's height

is controlled by changing speed.

[crashing]

Or you could just fly into a tree.

If he'd throttled up,

the airspeed hitting
the canopy would've increased,

producing more lift
to make it over the tree,

but he-- he didn't do that.

Anyone know how to remove
a tree from a paraglider?

Now it's time for question three.

We've seen Bernoulli's principle
at work on motorized vehicles,

but how does a hang glider
use it to stay airborne?

[playful music]

Like any wing, a hang glider works

by making air move faster over the top.

But instead of an engine,

they harness gravity to generate lift.

But when it's time to touch down,

Bernoulli's principle has to make way

for other scientific concepts...

-[man yelling]
-[crashes]

Like friction.

[man 1]
Ow. Ow!

[man 2, off-screen]
Are you all right?

[man 1] I think I might have broke
my elbow. I don't know.

[man]
Maybe you should try a safer sport,

like snake juggling.

[man]
Ow.

[man]
And that, class,

is Bernoulli's principle
of fluid velocity.

Lots of speed gives
a large pressure difference,

and lots of lift,

and lots of pain.

[glass shattering]

[electricity crackling]

[shattering]

We humans exercise
for all sorts of reasons.

Weight loss, fitness,

improved flexibility, posing.

But hamsters do it for the rush.

Research suggests that running

might lead to a sense
of euphoria in hamsters.

[squeaks]

Oh, I think he's hit the wall.

The good news is that us humans

have been getting in
on the action as well.

[man, off-screen]
Go man!

[man]
Cropping up in parks and playgrounds,

these oversized hamster wheels
are creating quite a stir.

[man] Don't slow down, there's a
predator on your tail!

[man]
We just haven't figured out...

how they work yet.

[laughter and cheering]

If, like me, you dream
of having a hamster's physique,

and I don't mean the big cheeks
and the stupid stubby tail,

put your best foot forward and join me

for a spin through the science.

She applies a force to the wheel

to generate angular momentum

so it starts to rotate.

[electronic music]

This momentum, combined with friction,

drags her feet backwards as it spins.

So she lifts her leading leg
high to drive the wheel

and takes large strides
to keep pace with it.

To stop, she slows gradually,

allowing the wheel
to lose momentum.

Tumble on a hamster wheel,

and it'll toss you around like a salad,

so you've got to slow down carefully.

Here's a young lab rat filming himself

for scientific purposes.

Yeah, you look great. Get running.

The wheel is rotating
with a linear velocity

of nearly 10 miles an hour.

Not bad.

But I reckon he'll be
getting tired round about...

[thuds]

...now.

Maybe three hamsters
will be better than one.

[laughter]

Or maybe not.

[laughter]

Well, we've seen what happens
when we come to an abrupt halt.

But hamsters are smaller
and proportionally lighter,

with a lower center of gravity.

This means they can
pull off stunts like this.

Hamish used centrifugal force
to complete his spin,

so simple when you're small and light.

Ah, this hamster wheel

is for little people to crawl through.

[woman, off-screen] Come on,
so you can have more rides!

Yeah, now you've got it!

[man]
Um, not quite.

She's supposed to be in the wheel.

[woman, off-screen]
Oh, my gosh!

[man]
What? What's going on?

Oh, good grief.

-[woman laughing]
-[child thuds]

[child]
I liked that, Mommy!

[man]
That's nice, darling.

Mummy needs to sit down now.

[woman, off-screen]
Oh, my gosh!

[electricity crackling]

[man] As you know,
when it comes to fashions and trends,

I am at the cutting edge.

Yo-yos, pogo sticks,
the Rubik's Cube,

I've been there
and written a postcard.

These days,
I'm all about the Hula-Hoop.

[male reporter] America's
newest gift to the continent:

the Hula-Hoop craze,
spreading like wildfire

in lands already ravaged
by rock and roll.

[man]
Everybody loves the hip-swinging fad.

Businessmen, chimney sweeps,

even c*ck waitresses...

And their customers.

[playful musical sting]

It has been mentioned often

that old Snake Hips Hammond

makes hula-hooping look like magic.

It isn't.

It's centripetal force,

friction, and torque.

[electronic music]

Our hoopist starts the spin

by sharply rotating the hoops
around the body,

creating centripetal force.

The friction between her body and the hoop

allows the hoopist to generate torque.

By rotating the hoop around her waist,

she creates angular momentum,

preventing the hoop
from falling to the ground.

Hula-hooping might look
like child's play,

but to nail the technique,
you'll need to know the basics.

First up, to get the hoop gyrating,

it needs a short, sharp spin.

Sounds simple.

Great action.
Now let's try it with the hoop.

[woman, off-screen]
Want to try it again?

[man]
I'd quit whilst you're ahead.

To get a hoop spinning,

you need friction,

but not too much.

This looks more like it.

Hips swiveling, torque,
centripetal force,

groovy purple leggings...

-[shattering]
-[woman yells]

Where's she gone?

When the hoop lost its axis,

it became a m*ssile.

-[shattering]
-[woman yells]

She might want to
head outside next time

she attempts aerial hooping.

That's better.

Dad's giving his daughter

a master class in centripetal force.

[thwacks]

Oh, dear.

Today she's learned
that centripetal force

only works when the hoop
is spinning around an axis.

[thwacks]

And he's learned not to
show off with kiddy's toys.

[thwacks]

[glass shattering]

[electricity crackling]

[shattering]

And that brings us to the end

of yet another monstrous montage
of scientific misfortune,

but before you go, let's take a moment

to consider the many brave scientists

who've put their necks on the line

so we could learn from their mistakes,

and laugh at them.

Good-bye.

[lively fiddle music]

[crashing]

[laughter]

[man]
Aah!

-[man screaming]
-[crashing]

[grunts]

[woman yells]

[thuds]

-[crashes]
-[groaning]