08x05 - Building a Champagne Tower, Taking Off in a Paraglider, Vortices

[bunniefuu]

DALLAS (off-screen): This

is the Science of Stupid.

Yes, this is the show where

we stir science into a

test tube of stupid.

Prepare yourself to see our

dedicated researchers take on

the universe's great mysteries

without any clue as to what

they're doing.

We'll reveal what went wrong

and why with the help of such

scientific principles

as brittle fracture,

defensive behaviors

and gravity.

The story of the foolhardy

versus physics always

ends in pain.

So, watch out it's

the Science of Stupid.

In this show we'll be looking

at elastic restoring force,

thrust.

MAN (off-screen): Oh.

DALLAS (off-screen): And

impact force but first this.

Paragliders, they're

an ambitious bunch.

They've been known to launch

off Machu Picchu in Peru,

The Great Wall of China,

even the summit of Everest,

which is remarkable really,

especially when you consider

that merely launching

off a gentle hillside.

DALLAS (off-screen): Can be.

Scientifically complicated.

Not to mention dangerous,

wherever it's done paragliding

should only be attempted

by the highly trained and

adequately equipped but it

appears even they seem to be

struggling with the launch.

So, let's take a good run up

and leap into the science of a

paragliding take-off.

DALLAS (off-screen): To launch

our man positions his wing to

the correct angle of attack

so air can fully inflate it.

The wing shape deflects

the airflow downward,

which creates an equal and

opposite reaction upwards

or lift.

The faster the air speed

over the wing the more

lift is generated.

Our man can increase

this by running forward,

which comes with

its own problems.

In summary, more air

speed, more lift.

It's such a simple equation.

Surely the only way

from here is up?

DALLAS (off-screen): This chap

is struggling to inflate his

wing but he's off anyway.

Just a short haul then.

His wing isn't at

the correct angle,

so isn't inflating properly,

thus when a sudden gust of

wind increases air speed

he can't control the lift,

which luckily doesn't

last very long.

MAN: Sorry.

DALLAS (off-screen):

Much better.

Perfect angle of attack.

I can't complain, he's

definitely generated lift.

Shame he won't actually be

enjoying the flight too.

Onto tandem take-offs and with

more mass you need more air

speed, well more

than that anyway.

Even running they don't

increase the air speed enough

to generate sufficient lift,

but they do get to find out

what's over the cliff.

Now, this looks promising,

tandem take-off but with some

real speed.

MAN: Looking good.

Looking good.

MAN (off-screen): Oh.

MAN: Almost.

DALLAS (off-screen):

Yeah. Define 'almost'.

Here on the Science of Stupid

we've seen it all, the falls,

the fails, the flops but we

thought it was about time we

saw some people

getting it right.

In fact, getting

it really right.

Now, it's hard enough doing

one back flip but imagine

doing ten in one minute.

DALLAS (off-screen):

On a jet ski.

Meet stunt riders Dan

Rowan and Liam Mellett.

They're attempting to complete

ten synchronized flips,

a Guinness World Record title.

No mean feat.

Three more and

they've done it,

and that is a world record.

Congratulations lads,

go grab a towel.

Impressive but you really

shouldn't attempt this

yourself because while messes

Rowan and Mellett make back

flipping on a jet

ski look easy,

for the rest of

us mere mortals.

WOMAN: Woo.

DALLAS (off-screen): Just

staying on can be hard enough.

Okay, what's the secret to

becoming the best of the best,

aside from practice,

practice, practice?

Well, it's thrust.

Turning effect and

center of mass.

You knew that.

DALLAS (off-screen): Our

man's jet ski uses a pump and

impeller to force

water out of the back,

this creates a forward

force known as 'thrust'.

To do a flip our rider creates

a wave to use as a ramp,

he'll need maximum thrust

as he rides up the wave to

produce enough of

a turning effect.

By standing up straight he

raises the combined center of

mass of him and the jet ski,

increasing the turning effect.

He just needs to make

sure he holds on tight.

That's the theory but I don't

want any of you trying to put

it into practice.

Luckily for us we found our

own potential record breakers

willing to give it a shot.

DALLAS (off-screen): This

aqua pack man is practicing

his thrust.

Water is force one way,

he moves the other,

just like a jet ski.

Almost.

But when he lets go the

thrust direction changes

and so does his.

So, what happens when we

apply thrust with a jet ski?

In his case that happens.

Because if you don't have

enough thrust as you hit the

wave you might

start your flip,

but you won't complete it.

This lady is learning about

the turning effect in a rubber

ring and using the

wave as a ramp,

whether she wants to or not.

The rubber ring is providing

no thrust so she's unlikely to

produce enough of a turning

effect to complete a flip.

So, back to the jet ski.

More thrust.

MAN (off-screen): Oh.

DALLAS (off-screen):

But still not enough

of a turning effect.

To get that you need

to ride up the wave.

MAN (off-screen): Oh.

DALLAS (off-screen):

Not into it.

Okay, one last go and, yes,

standing up will maximize your

turning effect but

don't forget the thrust.

I think the record's safe.

Great balance, champ, but

can you guess the scientific

principle we're about to see

at this lobster crate race?

DALLAS (off-screen): Did

you work out the science we're about to see?

Yes, it's friction.

When our competitor runs back

across the crates he builds a

lot of momentum but as he

tries to stop after his final

leap his momentum overcomes

the small amount of friction

between his wet

feet and the dock.

For the purposes of scientific

enlightenment that, sir,

is a win.

As my late grandmother

used to say,

'Slow and steady

wins the race,'

and whilst that may

have been true for Granny,

when it comes to

stock car racing.

DALLAS (off-screen):

It's quite the opposite.

(crowd cheering)

Whatever happened to just

chatting things through?

You may feel the need, the

need for speed but on an oval

track you want

to have traction,

momentum and steering

sorted too and here's how

all that works.

DALLAS (off-screen): Stock car

racing usually takes place on

an oval track, so whilst

maintaining speed our man must

also navigate

constant cornering.

As he takes a corner

centrifugal force tries to

pull his car to the

outside of the turn,

the friction between the

wheels and the road surface

provides a centripetal force

that holds him round the turn.

If he's hit by another car

the force of the impact can

overcome the friction

at his tires,

causing him to lose

traction and spin out.

So, we need to keep traction

without losing speed.

It's a delicate balance.

I think we better see

some experts in action.

DALLAS (off-screen):

Speed, check.

Steering, check.

Traction, uncheck.

As our racer takes the corner

a nudge causes his back wheels

to lose traction,

he starts to spin,

and the other drivers

can't react in time.

Don't worry,

that'll polish out.

Onto the dirt tracks now but

will that make it harder or

easier to maintain traction?

It's harder, obviously.

Coming out of the corner he

gets a little impact from the

side, the dirt shifts under

his wheels reducing friction,

he loses traction

and ends up, well,

I'm no expert but those

wheels are getting

no traction up there.

Okay, back to the track and

we are beautifully balancing

centrifugal and

centripetal force here.

Taking a smooth line

around the bends to

maintain traction.

You know what?

I think we've cracked it.

What do you guys reckon?

There is little better in life

than celebrating a special

occasion with your

nearest and dearest,

when you hear the cork pop

you know it's time to party.

DALLAS (off-screen): And no

party is complete without a

champagne tower.

WOMAN (off-screen): Wow, oh.

DALLAS (off-screen): Very

impressive but three glasses

is literally the

minimum you could use.

Now, that is a tower

and now it's a duplex.

Now, you may have noticed that

champagne tower building can

result in a lot of accidental

demolition and broken glass,

so do take care but get the

science right and your dinner

guests will be simply awe

struck by your deep knowledge

of impact force, moving center

of mass and base of support.

DALLAS (off-screen): As the

champagne is poured the liquid

will create an impact force

against the side of the glass,

the flow must be controlled

to avoid pushing the glass's

center of mass outside

its base of support.

This is most important for

glasses higher up the tower.

They have a smaller base of

support as they rest on the

rim of the other glasses.

This makes them less

stable than the bottom row,

which have a larger base

of support in contact

with the table.

So, there you have it.

Technically tricky and

almost certainly pointless.

Okay party people,

you've heard the science,

now let's get building.

DALLAS (off-screen): This

confident chap has opted for

the single stacker,

it's a bold choice.

Bold but not sturdy.

As each glass is balanced on

the rim of just one glass even

the slightest movement will

mean its base of support is

suddenly reduced.

I think you traditionally

raise a glass.

This gentleman has

opted for the more

conventional pyramid shape.

That table looks sturdy,

which is good for stability.

Oh, expertly done, sir.

You're an honorary physicist.

I hope you've been

waxing that coat.

The impact of the bottle

on the table causes a small

movement in the tower, this is

enough to move the top glass's

center of mass outside

its small base of support.

Well, at least there

were no guests.

WOMAN: Chris, get it together.

DALLAS (off-screen):

Right, Chris. You've been told, this is all on you.

CHRIS: Get your lips

on the end of this.

DALLAS (off-screen): Oh, I'll

wait for a glass I think.

Thanks though.

This tower looks strong

with a broad base and

a sturdy surface.

So, it'll all be down

to the impact force.

MAN (off-screen): Go, woo.

WOMAN (off-screen): Oh, wow.

MAN: Here's the

good stuff honey.

DALLAS (off-screen):

Hang on, Chris.

That third bottle will

increase the impact force on

the side of the glass.

WOMAN (off-screen): No.

DALLAS (off-screen): Chris,

you've let us all down.

DALLAS: On the Science of

Stupid we pride ourselves on

our in-depth exploration of

the smarts and stupidity of

the human species but every

now and again we like to take

a detour and admire the beauty

and the beasts of nature,

and there's little so

beautiful or beastly

as the vortex.

DALLAS (off-screen): A tornado

is a vortex that can reach

wind speeds of over

250 miles an hour,

but vortices come in

all kinds of forms.

They can whirl up and carry

flames from fires forming

firenadoes and they can pop

up over bodies of water.

MAN: Look at that,

it's a tornado on the water.

MAN (off-screen): Look at it.

DALLAS (off-screen): No my

friend, that is a waterspout.

MAN: It's really, really, close.

DALLAS (off-screen): Yep,

so I would consider running.

MAN: Coming right at me.

DALLAS (off-screen): No,

just gonna stand there?

MAN (off-screen): Whoa.

DALLAS: Bad idea because

whilst they are varied in size

and power vortices are all

unified by the same head

spinning science, which can

be demonstrated by a simple

bottle of water and, well,

our very own firenado.

DALLAS (off-screen): A vortex

can occur in anything but

flows, such as air or water.

The sides of this bottle

provide a centripetal force

that causes the water to

rotate and form a vortex as it

drains out.

Next our firenado.

As the heat of this flame

causes the air to rise the

wire mesh imparts rotation to

it as the air gets pulled in

by the low pressure

at the center,

it spins faster and higher

due to conservation of

angular momentum.

Now, our firenado was built

under expert guidance,

please don't go messing around

with fire yourselves but now

you know how a

vortex is formed.

Where in the world

might you see one?

DALLAS (off-screen): A

camping vacation in the

American Midwest, perhaps?

Here air heated by the ground

is rising whipping the tents

up into the air.

The rotational airflow of the

vortex causes them to circle

the crowd below.

I guess no one

brought any tent pegs.

The last thing you'd want on a

skydiving trip is to fly into

any wayward vortices.

Luckily there doesn't

seem to be any here.

MAN (off-screen): Oh, God.

DALLAS (off-screen):

That you can see.

As our skydiver comes in to

land the rotating air current

of our vortex sped up by

the conservation of angular

momentum, whip up dust

and yank his parachute

to the side.

He did escape without

any major injuries,

but you have to say

that was very unlucky.

Here we have a kayaker

enjoying a paddle and now not

enjoying a vortex.

The rocks provide a

centripetal force,

deflecting the flow of the

river causing the water to

rotate and he becomes

trapped in the fast flow.

Luckily his friends fished

him out and luckier still.

MAN: You still had your

camera on, didn't you?

MAN (off-screen): Yes.

DALLAS (off-screen): He did

and how we've learnt from it.

So, vortices, beastly science

but beautiful to behold.

Vortex marshmallows anyone?

American boxer Willie Pep

claimed to be the only person

ever to win a round

without throwing a punch.

Very impressive if true but

for those new to boxing you

may want to practice your

punch before you get into the

ring, and what better way to

train than with a punch bag?

DALLAS (off-screen):

Providing it's properly fixed.

Well, don't look at me.

To make the most of our punch

bags and avoid a sucker punch

we're gonna need a

fistful of physics.

DALLAS (off-screen): When

our boxer hits this speed bag

kinetic energy is

transferred to it.

By carefully timing each punch

he can increase the total

energy in the system and so

increase the speed of the bag.

A freestanding punch

bag pivots at its base,

when punched kinetic energy

is again transferred to it but

now an elastic restoring

force returns it to the start

position, along with most

of the kinetic energy.

So, if you hit it hard

the bag hits back hard.

It seems like a

fair fight to me.

DALLAS (off-screen):

Lesson one,

when starting out go

easy or that'll happen.

Because he hits it hard he

transfers a lot of kinetic

energy to the bag but the

elastic restoring force causes

it to bounce back with

most of the kinetic energy.

Still, lesson learnt.

This kid's got the hang of it.

Perfect rhythm.

By timing it right and keeping

his punches small he's able to

manage the transfer of energy.

Now it's granddad's turn and he

hits hard but as long as his

timing is right he'll be fine.

Still got it.

That's a jumper, I mean.

When he misses his last punch

the majority of the kinetic

energy is returned to him via

the elastic restoring force

and, yeah, let's, uh,

try something different.

A suspended speed bag, these

are harder to hit as they

swing back to

the boxer faster.

This guy is taking

it nice and steady,

keeping that kinetic energy

under control until it's not.

Here the energy from the

boxer's punch exceeds the

metal attachment's

tensile strength.

He's almost too good.

And that dear friends is

the end of the show and,

as always, I must warn you

not to attempt any of the

dangerous stunts

you have just seen.

Biologist Thomas

Huxley once said,

'Science is common

sense at its best,'

but judging by this

lot common sense isn't common enough.

(music plays through credits).