03x20 - Most Painful Lessons

[bunniefuu]

[Dallas]
This is the Science of Stupid.

-[electricity crackling]
-[glass shatters]

Yes, this is the show
that pits science against stupidity.

Watch as misguided daredevils risk life,

and limb, for little more
than basic amusement.

[screams]

We'll reveal what went wrong and why,

with the help of some
fundamental laws of science,

such as impact force,

chemical reactions,

and not forgetting traction,

or lack thereof.

These people suffered
so that you could learn.

So listen up, it's the Science of Stupid.

[glass shatters]

[electricity crackling]

In this show, we'll be looking
at how energy is transferred

from one thing to another,

[screams]

discussing the joys of torque...

and explaining how to
avoid drag whilst cycling.

[man] Whoa! Whoa!

[Dallas] But first, this.

[glass shatters]

[electricity crackling]

[glass shatters]

As a child I always dreamt
of being a superhero.

Still do, every night.

But can you blame me?

Just imagine possessing the ability

to do things like bound between
the tallest buildings in a single leap.

Well, imagine no more.

Because, like this free runner,

some people have turned fiction into fact.

And other people have turned fiction...

-[body thuds]
-...into pain.

-[yells]
-[clatters]

Quite a lot of pain.

Yes, I'm afraid to say roof jumping
really is a thing.

It's also extremely dangerous,

and people do get seriously hurt.

All the more reason
to check out the science.

Our expert free runner
builds momentum,

and launches at an angle
of around 35 degrees

to maximize distance.

In flight, he brings his feet
in front of his center of mass

to allow him to resist
his forward momentum on landing.

When he lands, he flexes his hips,
knees and ankles to reduce impact force.

Right, let's start with a launch,

and for maximum distance
the optimum launch angle

is between 15 and 35 degrees.

And the momentum is, well, lots.

This roof jumper sought expert advice.

[man, off-screen] As your legal counsel,
I advise you to not [bleep] do this.

-[man] Whoa!
-[Dallas] So would I.

Still, at least he's got a long run up.

-[all] Ohh!
-[bleep]

[Dallas] Shame it didn't help.

Building lots of horizontal momentum,

then converting it into
a 35 degree upward leap

is not helped by running
downwards on a sloped roof.

[friend] Holy [beep].

[man] You guys didn't catch me.

[Dallas] No, they didn't.

-[men laughing]
-They're also laughing.

[man]
You guys didn't catch me at all.

[men laughing]

[Dallas] Time to impress the girls
with scientific ingenuity.

He's chosen a launch point

that's much higher than his landing point,

so he can use gravity
to increase his momentum.

[man screaming]

It... it kind of worked

because he hit the roof with momentum

equivalent to
a seven-kilo bowling ball

traveling at 181 miles an hour,

and even had a bit left over
to hit the car with.

[man screams]

But don't worry, it was insured.

Now if our leaper does manage
to land on the other side,

he must bend those legs.

This can decrease the average
impact force by around 19%.

Mind you, if he does
have enough momentum

to get to the other side...

[screams]

...he'll probably have a bit to spare.

Or rather a lot.

[screams]

Now don't forget, it can also help to land

with a center of mass behind the feet.

[yelps]

That was in front.

Of course, there is another reason

lots of momentum can be your downfall.

Weak roofs.

Somebody help him.

-No?
-[men laughing]

Just point and laugh then.

[laughing]

[electricity crackling]

[creaking]

[clatters]

Of the many scooter tricks I've attempted,

the one I've always struggled
with is the tail whip.

Launch yourself into a jump,
flick the deck around,

land and roll on.

It's not easy,

but nailing one is nothing less
than pure legitness.

[boy] Yeah!

That was legitness.

[Dallas] I think that means good.

On the other hand, messing one up is more,
well, how can I put it?

[groans]

Yeah, that just about sums it up.

And to avoid all that, you need to know
about angular momentum,

the conservation of linear momentum

and the scrapey painful side of friction.

He builds many momentum
on approach to maximize air time.

Leaving the ramp, he uses his feet

to apply a turning force to the deck,

giving it enough angular momentum

to complete full revolutions in the air.

Landing with the wheels
pointing directly forwards

results in a very low resistance
known as rolling friction,

allowing him to conserve

most of his linear momentum
and roll safely on.

Now, in life I've found I've failed
as much as I've succeeded,

but in failing I've learnt so much more,
which is good news.

[screams]

Especially for him.

By kicking the scooter
plate out as well as around,

he gave it angular
and linear momentum,

when he only wanted angular.

[man, off-screen]
Ooh, he's split his face.

[Dallas] Yeah, I think he knows.

It also doesn't pay to overdo
your angular momentum,

especially since you need
to time that spin perfectly

so as to land back on your scooter
with the wheels pointing forwards.

As opposed to on your knees.

[boy, off-screen]] You all right?

[Dallas] Fine, touch of friction.

Can he nail his landing?

-[groans]
-Not really.

He got plenty of angular momentum,

but landing with his feet on the ground
instead of the deck

results in around 200 times
more frictional resistance.

Better luck next time.

[man groans]

Assuming there is a next time.

Right, make way for the little expert.

Nice!

You, sir, are master of
angular and linear momentum.

[boy] Yeah!

[crowd cheering]

[Dallas] Go on, son.

[boy] Yeah!

[Dallas] He was okay, but maybe forget
the fist bump next time.

[boy] Yeah, Jordan!

[electricity crackles]

[creaks]

[Dallas] These two are having
loads of fun just swinging about,

but what science is their friend behind
about to demonstrate?

[glass shatters]

[electricity crackling]

[glass shatters]

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

-[man] Oh, [bleep].
-[laughter]

[Dallas] It's vertical velocity.

Had he timed his run to jump
with the swing at its lowest point,

he'd have needed less
vertical velocity,

but he didn't so he needed more,

resulting in a large turning effect

and a really large impact force.

[man, off-screen] So close!

[Dallas] Not really.

[man, off-screen] You are an idiot!

[Dallas] Really.

[electricity crackles]

[creaking]

Deep tread tires, high ground clearance

and engines with a high torque at low RPM.

Oh, yes, nothing handles
the rough stuff like an off-roader.

This is an off-roader.

This is not an off-roader.

[man, off-screen] Holy ****!

Ohhhh! Ooh!

I think that there's
another tree in there.

[Dallas] Off-roader...

Okay, you've ruined my point.

I'm afraid even with a 4X4

your biggest obstacle
remains the humble bump.

Be it the size of a molehill
or the size of a, well, this.

[engine revving]

An actual hill.

[man, off-screen]
Oh. Over again, over again!

[Dallas] Pop the bits
back on, it'll be fine.

[man, off-screen] Shut her down.

[Dallas] So scaling those
rugged hills isn't just

about the size of your wheels,

it's about the careful control

of momentum, torque
and harmonic oscillations.

Here's why.

Our off-roader builds
momentum on approach,

maintaining it on ascent
by shifting down gears

to increase torque or turning force.

This is better than accelerating hard,

which transfers the load towards the back

and risks tipping its high center
of mass over its base.

Steady driving also helps on rough terrain

because suspension stores
and releases energy

as it hits bumps,
potentially causing harmonic oscillations,

which can be amplified
by excessive speed.

To sum up, you need just
enough momentum and torque

to get you up that hill,

and when it comes to
those cheeky little bumps,

the rule of thumb
is to take things nice and easy.

So not like that.

The more he accelerated,
the bigger the oscillations became,

until he oscillated the roof off.

But what about bumps on a hill?

[man, off-screen]
Just take it easy.

[Dallas]
That's right, easy does it.

Just a little gas.

Yeah, that was a lot of gas.

Excessive acceleration,
lots of oscillations, and this.

One center of mass
unequivocally beyond base.

Back to the drawing board, eh?

Snowy hill? No problem.

Slipping into a higher gear
provides less torque,

which can actually give more traction
in slippery conditions.

[man, off-screen]
Oh-h*, here he goes.

[man] Work!

[man, off-screen] Holy ****.

[Dallas] Yeah, he may
or may not have been listening.

[man, off-screen]
We got a problem.

[Dallas]
Yeah, you could say that.

But there are obstacles that no amount

of momentum and torque will get you over.

Like that tree.

[man screams]

[man, off-screen]
I really liked that a lot.

[Dallas] Good for you.

And don't worry,

all of our off-roaders
have made a full recovery.

[bell rings]

[beaker shatters]

[gurgling]

And now for today's science lesson,

where we analyze a particular
scientific principle.

And today's theme plays a key part
in every known action

and phenomenon in the universe.

For instance...

a man punching a speed bag.

[screams]

A perfect strike.

Well, sub-perfect.

And a very angry skateboarder.

[screams]

A very sore, angry skateboarder.

Today, class, we are studying law.

The law of the conservation of energy,

which dictates that whilst
energy can be stored,

transferred or converted
into other forms of energy,

it can never be destroyed.

For example...

a moving racket has kinetic energy.

On impact, the ball deforms,

storing kinetic energy
as potential energy

and converting it back
into kinetic energy

as the ball rebounds.

Whilst little kinetic energy
is wasted in this process,

some is lost to the surroundings
as heat energy.

And sound energy.

Right, time for a test.

Question one,
what happens to kinetic energy

when one object collides with another?

Let's see if he can show us.

[man, off-screen] Fore!

[Dallas] He can!

Textbook transfer of kinetic energy.

Golfer swing transfers
kinetic energy to the ball,

ball hits beam then transfers
kinetic energy to his head.

And then the sea.

Question two, what is potential energy?

It's stored energy.

Pole bends,
storing elastic potential energy

before converting it back
into kinetic energy.

Mind out!

-[man screams]
-[crowd gasps]

Gravitational potential energy
is stored in you

when you're high up.

Go downhill and it's converted
into kinetic energy.

[biker gasps]

See?

Definitely more kinetic now.

He was okay in the end, unbelievably.

But I can't speak for the bike.

[biker groans]

As we've discovered,
something might lose energy,

but that energy doesn't just disappear.

So question three is,
what happens to it?

It's converted into less useful forms,

like this bike wasting its energy

by converting it into heat and sound
rather than movement.

[screams]

Ah, that's better.

So that's your science lesson.

Energy can't be lost, only stored...

[groans]

converted, and sometimes wasted.

[glass shatters]

[electricity crackling]

[glass shatters]

There really is nothing quite as relaxing

as a gentle cycle
through the countryside.

That said, if you are in a race,
things are a bit different.

For a start there's danger
around every corner.

[screams]

And if there's more of you,
there's more chance of this.

[man, off-screen] Oh, my God.

[Dallas] That's very messy.

It's suddenly not that appealing,

but if racing is your thing

you'll know that if you're cycling
in a group the rewards are great,

but the margin for error is slim.

And here's why.

In a peloton, riders save energy
by positioning themselves

within a zone with lower air resistance,

behind the front riders.

But riding this close can mean
more chance of a collision,

particularly on fast corners
where riders lean in

to counter the effects
of centrifugal force,

pushing them outwards.

This increases the width
of the area a rider occupies,

and as more force is directed sideways,

it can also lead to a loss of traction.

Thus pelotons can be
a nice place to settle in

and save some energy, as much as 40%

if you're tucked in the right spot,

but they're not exactly problem-free.

Thanks to the cyclists up front,

these two are enjoying
a pocket of low air resistance.

But not anymore,

because thanks to this wheel collision,

they're now enjoying pockets
of high ground resistance.

h*-h*, friction, you devil.

Of course fellow cyclists
aren't the only thing

that can affect air resistance,
there's also passing cars,

like that one.

[biker screaming]

Oh, watch out!

[gasps]

[man] ****! ****! ****!

[Dallas] You don't say.

On to cornering.

And it is a fine balance
between countering centrifugal force

and maintaining enough friction
with the road.

The optimal lean angle
for these guys is around 40 degrees.

[man screams]

There's always one.

Turning too hard, this chap here
lost friction on the back wheel,

sending his bike into a slide.

And when one goes down,
chances are so will he,

and him, oh, and him.

It's called a chain reaction.

[man] [bleep]!

[Dallas]
And it turns out he's always at it.

[man, off-screen]
Again? Second time today?

[Dallas] But if you can exploit
that low drag pocket

without doing things like this...

[men groaning]

...you'll save plenty of energy
to sprint to the finish line.

Just don't celebrate too early.

-[man groans]
-[laughter]

Yeah, you did that.

[electricity crackling]

[creaking]

[clatters]

Mah, champagne, that sparkling elixir,

liquid epitome of fine taste,
style and sophistication.

And that's not all.

-[man] Let's go!
-[laughter]

[Dallas] It can also be expensive...

unsightly...

[woman laughing]

-...not to mention... painful.
-[cork pops]

[giggling]

You see, what I have in
my hands, my friends,

is actually a bubbly ticking time b*mb

with a cork m*ssile wedged into it.

A 75-centiliter bottle like this

contains as much as five liters
of gaseous carbon dioxide

dissolved in the liquid,

under lots and lots of pressure.

Shaking encourages the carbon dioxide
to form bubbles of gas,

and the pressure goes up.

Loosen the cork, and those
bubbles rapidly multiply

and expand, hugely increasing the pressure

and propelling the cork at high velocity.

Carbon dioxide gas then rushes out

towards the lower pressure air
outside the bottle,

in an eruption of foam.

In a bottle like this, you could be
talking around 90 psi of pressure.

Triple that of your average car tire.

And that pressure
isn't gonna relieve itself.

It needs a little hand.

Or one of those.

I'll have a lemonade, thanks.

A popped cork can reach
almost 35 miles an hour.

-[cork pops]
-[man laughs]

They're also very bouncy.

But it's good that corks are squishy,

because bottles are quite hard.

Flinging champagne
creates more bubbles,

increasing pressure,

add a big enough shock to weaken the seal,

and you no longer have
a celebratory tipple,

you've got a rocket.

[yelps]

So if you are gonna pop that cork,

make sure you have plenty of space,

in all directions.

[glass shatters]

[electricity crackling]

[glass shatters]

The 19th century chemist
Sir William Ramsay once said,

"Progress is made by trial and failure.

"The failures are generally more numerous
than the successes,

yet they are usually left unchronicled."

How times have changed.

[screams]

[groans]

[screams]

[screams]

[screams]

[yelps]

[woman groans]