02x09 - Barbecues and Hammocks

[bunniefuu]

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

Yes, this is the show that
examines stupid stunts,

and reveals the science
behind what went wrong.

Join us, as we dissect
some gargantuan gaffes

and apply some
scientific wisdom.

We'll learn about

angular momentum...

[man, off-screen] Oh!

[Richard, off-screen]
Center of mass,

and gravitational
potential energy.

Step into the ring with science,
and you'll get knocked out.

Ignore it, and you'll find that
what goes around comes around.

Full steam ahead...

for the Science of Stupid .

[crash]

In this show, we'll discover
what happens

when you don't respect
flash points...

[screaming]

Make a hash of
your center of mass,

and when you find yourself
with a friction affliction.

[man] Ah!

[Richard, off-screen]
But first, this.

Have you heard of skitching?

Well, it's either
A, a form of needlecraft,

B, a sailing maneuver,

or C, hitching a ride
on a moving vehicle.

It's C.

And if you think that sounds
stupid and dangerous,

you'd be right.

[man] Ha! Oh!

♪ ♪

If your idea of fun
is being towed around

on a bit of rope
by a speeding vehicle,

don't come running to me

to patch up your grazed elbows
when you fall over.

I mean, I'm not even a doctor
or anything.

However, if you do insist on
pursuing this crazy endeavor,

at least put some science
into the stupidity,

and give yourself
the best chance

of avoiding a trip to hospital.

When someone is being towed
by a moving vehicle,

the best place for them to be
is directly behind it,

so that the towing force is
pulling them forwards.

As he drifts to the side,

the towing force
can more than double,

and will have
a sideways component

that pulls him back
towards the center.

To remain out to the side
of the vehicle,

he must constantly steer
in that direction.

If he lets go,
or slackens the rope,

the towing force disappears,

and he'll carry on in whatever
direction he was steering.

Skitchers try to stay
behind the vehicle

to negate those sideways forces,

because if they fall, they run
the risk of getting road rash,

which can damage blood vessels
and nerve endings,

not to mention possible injuries

to the head, spine
and internal organs.

I don't think I'll be giving it
a go anytime soon.

Or ever, in fact.

[screams]

[Richard, off-screen] Okay, one of these
skitchers has a helmet,

the other doesn't.

Oh, maybe he thought the
Frisbee would help.

It didn't, though.

When Mr. No Helmet lets go,

his sideways force disappears,
throwing him off balance.

[screams]

I think he needs some
new glasses, as well.

These skitchy scientists
are using longer ropes,

but what difference will it make
to the outcome?

Absolutely none.

This guy is either
brave or stupid.

[laughs]

[man, off-screen] Oh!

[Richard, off-screen]
Yeah, it was stupid.

Definitely.

That isn't a ride-on
lawn mower, you know?

[woman] This is terrible.

[Richard, off-screen] See, I'm not sure
this is such a good idea.

[woman] Oh woah!

[Richard, off-screen] Oh,
okay, I take that back.

That is actually quite
impressive.

[woman laughs]

When his string goes slack,
the towing force disappears,

and so does his ability
to stay straight.

[woman laughs]

There's one bush in this road,
and you manage to crash into it.

Ah, now, this is more like it.

Oh, dear, hang on,
he's speeding up, a lot.

This isn't good!

He's having to counteract the
turning effect of the tow rope,

so when he lets go,
he's still leaning back.

At 23 miles an hour,

the skate wheels will be
rotating over nine times faster

than the car's wheels.

To avoid falling, he'd have
to be running faster

than most 100-meter sprinters.

And that is why you should
not try this at home.

Fire breathing,
an impressive stunt

that has been performed
for hundreds of years,

from medieval traveling troupes
to circus acts,

rock and roll bands, and
irritating people at festivals.

Call me a wuss, but I can't say
I have ever been tempted

to try something that carries
a very real threat

of setting your head on fire.

[cheering]

As you can see, even
a professional can end up

needing a shower with
a fire extinguisher.

The fireball from fire breathing
can be very powerful,

and the world record
for the highest flame

from fire breathing
stands at over 26 feet,

but it's certainly
not just a case

of spitting flammable
liquids on a flame.

Fire breathers need to
understand some serious science.

[Richard, off-screen] Using the
correct fuel is very important.

The right fuel is one
that evaporates

at higher temperatures.

Scientists would say such a fuel
has a high flash point.

♪ ♪

Fire breathers blow fuel
across a flame,

triggering a chemical reaction,

which creates a fireball
of burning vapors.

The fuel must also be sprayed
in a fine mist,

to ensure that
it evaporates quickly.

♪ ♪

So, remember,

fire breathers use
high flash point fuel

that only evaporates at
a high temperature,

because low flash point fuels
may burn back in your mouth,

or ignite on your face.

And nobody really wants their
face on fire, do they?

[Richard, off-screen] Excellent!

A professional entertainer
who knows exactly

how it should be done.

Bravo!

No need to go again
on our account.

Oh!

Oh, yeah, you should've quit
whilst you were ahead.

[screaming]

Setting fire to spirits
is dangerous

and should never be attempted.

High-percentage alcoholic drinks
have a low flash point.

[screaming]

Yeah, I'd just drink it
next time, mate.

Did I mention how volatile
spirits are?

[screaming]

No? Well, they are.

I wonder if this chap knows
how volatile Sambuca is?

Well, he does now.

That is officially stupid.

Ever consider just
having a lager?

[man] That guy's a dragon.

And that guy will be a dragon.

And that guy's a
previous dragon.

He's no longer a dragon.
He's not cool.

[man laughs]

[Richard, off-screen] Now, I've never
seen a dragon with his face on fire.

Fuel with low flash point
equals burnt chin.

[man laughing]

I really, really hope
he knows what he's doing.

No, his head is on fire.

Because the fuel's flash point
is too low,

the drops around his mouth
catch fire.

[screaming]

[man] Hey! Are you ready?

[Richard, off-screen]
That's a jerry can.

I do hope it's not
gasoline inside.

[man] Yeah!

[laughs]

[Richard, off-screen] Yeah,
that's gasoline, alright.

It has a low flash point,

but, ironically,
has a burning temperature

of over 2,000 degrees
Fahrenheit.

Amazingly, he and the others
in these clips

weren't seriously injured,

but you definitely should not
try this at home.

Why would you?

[screaming]

A little science teaser now.

What scientific law is
this holiday maker

about to demonstrate?

[man] Woo-hoo-hoo!

[woman screams]

[woman laughs]

[Richard, off-screen] This
holiday maker is demonstrating

the turning effect of forces.

When all the people are
sitting on the boat,

the forces are in equilibrium.

But when our man jumps out,

the boat is being turned one way
more than the other,

causing it to capsize.

[woman screams]

[woman laughing]

When I'm out on my skateboard
or roller skates,

nothing beats the buzz of
overcoming a flight of stairs.

I like to mix it up.

Sometimes I jump the whole lot,

sometimes I grind down
the handrail,

but there are some serious risks
to your undercarriage

if anything goes wrong.

♪ ♪

[screams]

As you can imagine, doing
the splits unintentionally

when you're on roller skates
or a skateboard

can be very painful.

To successfully land on wheels,

without your legs tearing away
from each other,

you might want to pay attention
to this science.

[Richard, off-screen] A skateboarder or
roller skater

jumping forwards has momentum.

For a smooth landing, he must
keep all wheels facing forwards,

and his center of gravity
above the base.

Bending his knees on landing
will help correct minor mistakes

in the position of
his center of gravity.

♪ ♪

But if you get that wrong,

and a foot comes off the board,
or a skate is turned sideways,

friction can stop that leg
from moving,

whilst the other
continues forwards,

and from then on,
it's all just bad.

Do we really want to see

these next brave researchers
in action?

Yeah, course we do.

[Richard, off-screen] Okay, keep your
center of gravity above your base,

and you'll be fine.

Oh!

[laughing]

Even his board has split.

[man, off-screen]
Ah, you [bleep]!

[Richard, off-screen] Well,
at least he enjoyed it.

[laughs]

[laughing]

Here we go then.
I can hardly watch.

[man] Ah!

[Richard, off-screen] Is
it over? I closed my eyes.

Oh, great, there's a replay.

[man] Ah!

[Richard, off-screen] When
his foot hits the ground,

the friction stops his back leg,

and then it's a one-way ticket
to Splitsville.

[man] Ah! Ah!

[Richard, off-screen]
Please, not you, as well!

[screams]

[man, off-screen] Oh!

[Richard, off-screen] No!

I can't take much more.

Once his foot hits the floor
and the friction kicks in,

his legs tear apart
from each other

at around 20 miles an hour.

[man, off-screen] Oh!

[Richard, off-screen] Okay,
I'm thinking positive.

This guy will nail it.

-[man] Are you ok?
-[man 2] No I'm not.

[Richard, off-screen]
No, nor am I.

His back foot slips off
the board as he lands.

By now, we all know what
a nemesis friction is

in that situation.

-[man] Are you ok?
-[man 2] No I'm not.

[Richard, off-screen] Well,
not surprising, really.

The balance beam.

Beautifully simple,
impressively variable,

and when it goes wrong,
stupidly painful.

♪ ♪

[groans]

[man laughs]

[groans]

Most men will tell you

that watching someone
slip on the beam

can be seriously
wince-inducing.

It's even more so if it's done
off the back of a somersault.

To somersault on a beam,
there is, as always,

some science to get
your head around.

[Richard, off-screen] By leaning
backwards as she jumps,

her center of gravity is no
longer directly above her feet,

making her rotate.

To stay on the beam,

she must push off with one foot
in front of the other,

with her body facing
exactly down the beam,

so that as she rotates,

her center of gravity moves
parallel to the beam.

♪ ♪

That seems pretty difficult to me,

so before we start
somersaulting,

let's just master
walking on the beam.

Here's a few pointers.

[Richard, off-screen] First,
find yourself a solid beam.

[man laughs]

[man laughs]

If you can't
afford a gym,

a local park can provide
a handy place to practice.

[woman, off-screen] Oh!

That was terrible!

[Richard, off-screen] Finally, take
advice from elders and betters,

like this teacher, for example.

[man] Oh!

[laughter]

[Richard, off-screen]
But he's certainly older.

[man] Oh!

Right, then, I think
we're ready to move on

to the somersault and apply that
science we learnt earlier.

Actually, we're clearly nowhere
near being ready

for the somersault,
but let's do it anyway.

[Richard, off-screen] He's not
doing what I think he is, is he?

[gasps]

Gyms have soft crash mats
if you fail.

A half-built skyscraper
does not.

[man, off-screen] Ooh!

[Richard, off-screen]
It has a very long drop.

Because his body isn't facing
directly down the beam,

his center of gravity doesn't
move parallel to the beam

as he rotates.

An inch further,
and he'd be dead.

Please, for the love of science,
do not try this yourself.

[man] Oh!

[man, off-screen] Oh!

[laughs]

[Richard, off-screen] I think it's safer
if we move this into the gym.

Did you know men don't compete
on the beam in gymnastics?

[man] Whoa!

[Richard, off-screen] And
that's one reason why.

[man] Whoa!

[Richard, off-screen] Because
he rotates 90 degrees

around his center
of gravity,

his feet land either side of
the beam, rather than on it.

Yeah! Lesson learned!

Oh, another backward
somersaulter.

I can hardly watch!

[man laughs]

And yet I did
watch! I watched!

[man laughs]

Because he pushes off
with his left foot

more than his right, his center
of gravity moves to the right,

and his feet miss the beam,

but his bum certainly didn't.

[man laughs]

So, let's finish
with a flourish.

[gasps]

Not what I had in mind.

She's off balance after
the first rotation,

and so her center of gravity
moves sideways,

and her feet miss the beam.

For millennia,
man has been fascinated

by the myth of walking on water,

and it's become a synonym
for the impossible task.

So, imagine my surprise
when I discovered

that there are people out there

who actually think
they can run on water.

[grunts]

♪ ♪

[screams]

Okay, so
it's clearly impossible.

I dare say those guys on
the lake won't believe me,

but I have science on my
side, and here it is.

[Richard, off-screen]
It's all about buoyancy.

In a swimming pool,
most people can float

with the majority of their body
just below the surface,

but to run on water,
you'd need to float

with all of your body
above the water.

To overcome lack of buoyancy,
you'd need to run very fast.

If you could slap your foot down
on the water fast enough,

the inertial force generated
would be great enough

to stop you sinking
for a split second.

To actually run across
a body of water successfully,

a human would need to be running
at around 67 miles an hour.

That's about three times
faster than Usain Bolt.

Still, we can but try,
and completely fail.

[man, off-screen] Okay.

[Richard, off-screen]
Here we go!

[laughs]

Well, that was pretty good,
actually,

but I think it's just
shallow water.

[man] We have a little bit more
of a scientific background.

[Richard, off-screen] Yeah,
okay, enough talk. Wow us!

I'm not angry,
I'm just disappointed.

[man] Ready...
Set...

[Richard, off-screen] Well, this
isn't water running. That's ice!

[man] Go

[Richard, off-screen]
Okay, now it's water.

I think we are all in agreement

that trying to run on water
is a waste of time,

but if you lay something buoyant
across the water,

it definitely becomes possible.

Possible, but still not easy.

[Richard, off-screen] Maybe this
lady will be able to stay dry?

No, it's a muddy bath for her.

[laughs]

Lily pads. Are these any easier?

[man] Haul a*s!

[Richard, off-screen]
Yes, easy-peasy!

[man, off-screen] Yeah!

[Richard, off-screen]
Right, next!

Oh, dear! Come on, you just
saw how simple it is.

I think the problem here...

[man, off-screen] Whoa.

[Richard, off-screen] Is you.

[laughs]

When I'm training for
Ironman events,

I put a lot of hours in
on the monkey bars.

They can be found in parks,
playgrounds,

as*ault courses,
and monkey enclosures.

But I don't use those ones,
obviously.

Well, not often.

I'm a member of a gym.

♪ ♪

[man] Oh!

[man, off-screen] You alright?

[man] Woo.

If you fancy yourself
as a king of the swingers,

but don't want to make
an ape of yourself,

here's a few tips to
stop you getting hurt.

[Richard, off-screen] To
move across monkey bars,

he needs a lot of grip
strength from his muscles

to provide an upwards force

large enough to
balance his weight.

He must ensure the palm
is facing forwards,

for maximum flexibility
and range of motion.

If he misses a bar
and drops suddenly,

the force he needs to apply
to avoid falling can double,

equaling his body weight,

plus the force required to stop
his downwards momentum.

He must also make sure
to get a good rhythm

in order to keep his
forwards momentum going.

You see, monkey bars
are pretty tricky.

They're not just a place that
monkeys go to get drunk.

Bars.

Monkeys in them.

[cough]

Sorry. Crack on.

[Richard, off-screen]
This guy looks the part.

So far, so good.

[woman, off-screen] Oh!

[Richard, off-screen] Yeah,
when his hand misses the bar,

his muscles can't provide
the upward force

to stop him falling.

[woman, off-screen] Oh!

Oh!

[Richard, off-screen] Hopefully this
little monkey will have more luck.

Nope! He lost his momentum.

But if there was a prize
for air running,

he'd definitely win it.

[man] Mark, get set, go!

[Richard, off-screen] Ah, how
far can you get, little man?

Oh! Not far.

No, not far at all.

Oh!

Wowzers! This kid is good.

He's got good grip,
good momentum.

He's gonna make it!

Ah, I'm not very good
at these predictions, am I?

[man, off-screen] Ooh!

Well, that's quite enough

agonizing analysis for now.

If you don't want to end up
like those masters of misery,

don't try what you've
just seen at home.

[man] Oh!

[man laughs]

[man] Ah!

[woman laughs]