03x08 - Stops, Front flips and Sliding

[bunniefuu]

[Richard]
This is the Science of Stupid.

-[electricity crackling]
-[glass shatters]

[alarm blares]

Yes, this is the show
that fuses hard science

with soft-headed-ness.

So stand well back as our team
of nuclear-powered nitwits

tackle logic head-on

and go face-to-face
with the painful facts of physics.

Through their complete disregard
for personal safety,

we can tackle key principles,

such as the full impact of fluid pressure,

the hard-hitting facts
of moment of inertia,

and the uplifting side of G-force.

In the battle of logic versus lunacy,

there can be but one victor.

So, sit back.

It's the Science of Stupid.

[electricity crackling]

In this show,
we'll come face-to-face with trajectory,

get down and dirty with viscosity,

-and we'll feel the heat of combustion.
-[man screams] [bleep]!

[Richard] But first, this.

[glass shatters]

[electricity crackling]

[glass shatters]

When a gymnast
needs that extra bit of oomph,

they use a springboard or a trampette.

It allows them to
jump higher, leap further,

and, of course, crash harder.

They can add boost to your bounce...

as long as you jump on them.

To prevent injury, land on a mat,

not next to it.

And don't abuse
your new bouncing super powers.

[groans]

Or you'll come back
to Earth with a bump.

Before you start somersaulting
off your bed springs,

I suggest you take a running jump
at the science.

First, she runs and jumps,

generating lots of kinetic energy.

This is converted into
elastic potential energy

as the springs compress.

As they rebound,
she receives a burst of kinetic energy,

giving her more height for a flip.

She increases her angular velocity
by tucking in tight,

making her moment of inertia small.

She then slows her spin
by extending her legs

to complete the flip,
ready for a perfect landing.

A trampette gives you
a similar kind of boost,

storing its elastic potential energy
by stretching,

but whichever you use for a big bounce,

you've got to put energy in,

and that means hitting it
with a bit of pace.

A good run-up should give him
plenty of bounce.

[yells, groans]

Well, it would have
had he hit the springboard.

[yells, groans]

But it could have been worse.

See.

[man, off-screen]
**** you all right?

[Richard] Doubt it.

Opting to forgo a run-up
meant this gymnast

had plenty of vertical velocity

but no horizontal.

Once airborne, it's time to perform
your aerial acrobatics.

Remember, if you want to spin quickly,

you make your moment of inertia small

by tucking in your arms and legs.

-[bone cracks]
-[groans]

So not like that.

-[bone cracks]
-[groans]

Thankfully, gymnasts
are renowned for being flexible.

This one can touch his toes...

with his face.

He failed to turn his
small moment of inertia into a large one

by stretching out for the landing.

Yeah, that sort of thing.

This gymnast is at the top of her game.

Let's hope that success
hasn't gone to her head.

-[bone cracks]
-[man, off-screen] Oh!

[Richard] I spoke too soon.

Hitting the board
at over ten miles an hour,

she had plenty of horizontal velocity,

loads of vertical velocity,
but when her hands slipped,

she didn't create enough angular velocity,

and her flip... flopped.

[electricity crackles]

[creaks]

When you throw a ball,

do people laugh and point as it flies off

in completely the wrong direction?

No? That'll just be me then.

In the right hands,

a thrown ball can be a thing of wonder.

[man] Whoo!

[Richard] In the wrong hands...

[shatters]

...it becomes a m*ssile.

[shatters]

Or to be more accurate, a projectile,

and projectile motion
is the science you need to learn

if you want to make the perfect throw.

By bringing his arm back,

he can apply a force to the ball
over the longer time,

thereby transferring
more momentum to it

and making it fly faster.

His teammate can still cover
as much ground with less momentum

by throwing it around 45 degrees,

the optimum angle for maximum distance.

So remember,
it's just a case of throwing the ball

with the right amount of speed
at the right angle.

Let's start with generating
that all-important release velocity.

The fastest-ever
baseball pitch was clocked

at an astonishing 105 miles an hour.

[all groan]

That was only 83.

There is one transfer of momentum,

and there's another.

[all groan]

Ha, missed both legs.

Basketballs have a greater mass
than baseballs

and need more energy to throw them.

And more energy to stop them.

Time for a spot of American football.

Go long. Go long.

Too long.

There was plenty of momentum
transferred to the ball,

and a fair bit
was transferred to the fence.

[yells]

So a high release of velocity
is a good thing...

-[groans]
-[man] Oh!

[Richard] ...but only when
you know it's coming.

Holding the Frisbee close
and then swinging his arm into the throw

gave the disc loads of momentum,

and it gave him... a nosebleed.

A fast ball is a good start

but only if you release it
at the right angle.

Let's see how a pro baller
handles his throw.

[man 1, off-screen] My goodness.

[man 2, off-screen]
I'm not sure what that was.

[Richard] Well, as you asked,
it was an example

of too high a release angle

and too little release velocity.

Good catch, though.

Now, one sport you don't
immediately associate with throwing...

[man, off-screen] Nice.

[Richard] ...is clay pigeon sh**ting.

It's a great way to practice
your sh**ting skills,

because no one gets hurt.

[man, off-screen] Ohh!

[Richard] Except for him.

The disc is supposed to be released
at the top of the swing

for the optimum launch angle,

but it wasn't.

[man, off-screen] Ohh!

[electricity crackles]

[Richard] Time for a quick teaser.

What scientific principle
are these BMX boys

about to demonstrate?

[glass shatters]

[electricity crackling]

[glass shatters]

Have you worked out the facet of physics

that's going to affect their leap?

[man, off-screen] All right, here we go.

Oh. Oh.

[Richard] That's right,
it was sheer strength.

The high pressure
created by the bike's wheel

exceeded the ramp's sheer strength,

and it broke, creating a turning effect
on that rider's bike,

and that one.

Well, one good turn...

[man, off-screen] Oh. Oh.

[Richard] ...deserves another.

[electricity crackling]

[creaks]

[clatters]

I love mud,

partly because it contains
a microscopic bacteria

which may increase
the level of our brain's

happy chemical, serotonin.

That'll explain this mucky lot,

but if the running wasn't tough enough,

these mud pluggers
are getting electrocuted as well.

Shocking, eh?

Whether you're running
through an electrified mud pit

or navigating a moist car park,

you'll be better off
knowing the science of crossing mud.

Mud has low sheer strength,

because it's made up of
flat clay particles and water.

When your foot moves across it,
the particles also slide.

Low compressive strength means
you're more likely to sink

when applying pressure.

Wet, sloppy mud has a low viscosity,

making it easier to wade through,

whilst thick, sticky mud
has a high viscosity.

This creates a vacuum
between your wellies and the mud,

leaving you in a sticky situation.

It's wise to check
mud's compressive strength

and viscosity before wading in.

You could use a stick,
or you could just do this.

[laughter]

Yep, that did the trick.

The increased downward pressure

combined with the mud's
low compressive strength

resulted in his sinking feeling.

And as the highly viscous sluggish goo
doesn't flow around his feet,

it's creating a vacuum,

keeping a firm hold of his shoes.

Even little puddles like this
should be treated with caution.

Told you.

A surprisingly deep hole,

and surprisingly low viscosity,

the mud's low sheer strength
makes it a challenge to get out.

His friends would help...

[laughing]

...if they could stop laughing.

Once you've tested the muddy waters,

it's time to take the plunge,

but remember, mud's low sheer strength

makes it very slippery,
so tread carefully.

Weren't paying attention, were you?

Landing on the slippery mud
with all of that forward momentum

meant that his base of his support
moves away

from his center of mass.

And his white T-shirt... not so white.

[man] Cut!

[Richard] This car's struggling
to a grip in the slippery mud.

-[man laughing]
-And so is he.

Maybe buy a pair of boots
or crampons, claws.

I don't know.

Pushing against the car
created a reaction force,

which sent his bare feet
in the opposite direction.

Come on, how's about one last shove?

Maybe not.

Mud's slippery lack of friction
isn't all bad.

He's been enjoying himself.

I don't know about everyone else.

[bell rings]

[beaker shatters]

[gurgling]

Pipe down, class.

It's time for your science lesson,

and the heat is well and truly on

as there will be a test afterwards.

So which of you bright sparks can tell me

how the heat from this engine
is scientifically linked

with the oxygen fanning these flames

and the fuel hotting up this barbecue?

[man, off-screen]
That was a bad idea, Tom.

[Richard] Yeah, he probably
has had better.

Today, class, we'll be looking
at how fuel, heat, and oxygen

come together to create combustion.

So fire brigade on speed dial.

Let's crack on with the science.

Light a balloon filled with hydrogen,

and it burns as it mixes
with oxygen in the air.

But light a mix of hydrogen and oxygen,

and it burns faster throughout,

because the oxygen
is already in the balloon.

With liquid fuels,
the speed at which flames propagate

also depends partly
on how their vapors mix with oxygen.

For example, this petrol releases vapors
far more quickly than this alcohol,

so the flame spreads faster.

As you've just seen,
fire is painfully hot,

can spread extremely fast,

and therefore is incredibly dangerous,

so do not mess around with it ever.

And now it's time for a test.

Oxygen makes up 21% of our air,

and fuel quite literally grows on trees.

But how do you create heat
if you don't carry matches?

The friction from this spinning tire
is generating loads of heat,

Just add some fuel...

[engine revving]

...and it's even hotter.

Is that why they call it a burnout?

No, I'd blow a bit harder, mate.

And here's another way
of creating heat.

By concentrating the sun's energy,

a magnifying glass can boost its power
by up to 250,000 times.

[man laughing]

[man] What the **** are you doing,
you *******?

What was that?

[Richard] It was elementary,
my dear Watson.

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

[Richard] Not to mention
it's a very bad idea,

so please don't copy this.

Fuels can either be
solids, liquids, or gas,

but my second question is this:

do all fuels burn in the same way?

Liquid fuel, like alcohol,
gives off a flammable vapor...

-[woman screams]
-...which ignites fairly easily.

[woman] ******** carpet!

[Richard] Spreads easily too.

But how well do gases burn?

[man screams] [bleep]!

[Richard] Really well.

Gases like the hydrogen
in this flatus ignition

are more combustible
because they mix easily

with oxygen in the air.

You really don't want to see
what he does for an encore.

[man screams]

And now on to
our third and final question.

We've learned how to start a fire,
but how do you stop one?

Santa knows if we've been good or bad,

so he should know
that to put out these flames

he needs to remove
part of the fire triangle.

By stopping, dropping and rolling,

he took away both the oxygen and the heat.

Sizzling stuff.

See you on the 25th, mate.

So we've learned
that heat, fuel, and oxygen

are all essential for combustion.

It's a dangerous mix,
so if you don't want to get burnt...

-MAN; [bleep]! [bleep]! [bleep]!
-[Richard] ...don't play with fire.

[glass shatters]

[electricity crackling]

[glass shatters]

Half of the fun of owning
a classic car is in the fettling,

squeezing a bit more power
from the engine,

or perhaps tweaking
the suspension for a smoother ride.

But smooth riding isn't at the top
of every petrol head's wish list.

Welcome to the world of the low riders,

classic American cruisers
kitted out with complex hydraulic systems

that allow them to perform outrageous acts
of auto exhibitionism.

There are less complicated ways
of making your car bounce.

Isn't that right, boys?

Regular air suspension systems
are filled with comfortable squishy gas.

Low riders, however,
are not built for comfort,

and here's the science to prove it.

The hydraulic system uses
a high-powered compressor

to push incompressible liquid
into the suspension.

As pressure is transmitted
through an enclosed incompressible liquid

with the same force as it was applied,

the car is pushed upwards
with roughly the same force.

To pull off the trademark bounce,

you need to engage
the suspension repeatedly.

It looks impressive,

but creating massive impact forces
is not so great for the car.

So low riders rise up and down
using liquid-filled chambers.

Get everything right
and you could pull off stunts like this.

But you don't want to bounce
too close to other cars.

Oh, that's gonna be
a complicated insurance claim.

Repeated bouncing
does have other drawbacks.

Ah, your wheel's gone wobbly.

Each bounce sees the car hit the ground

with the same momentum as a bowling ball

traveling at over 2,000 miles an hour.

So you can have too much bouncing.

[crowd yelling]

Um, any chance of a push?

When the front is lifted,
it created a turning effect

around its rear wheels.

Once the center of mass moved
behind the base of support,

gravity did the rest.

He's always wanted a soft top.

All of that bouncing
dissipates a lot of energy.

[woman, off-screen] You're leaking!

[Richard] And that generates a lot of
heat.

[woman, off-screen] You're leaking!

[Richard] So if it were to come
into contact with a flammable liquid,

like say, hydraulic oil...

-[woman screaming]
-[man, off-screen] Ohh! Ohh!

[Richard] ...your low rider
will become a hot rod.

[woman, off-screen]
I told you it was leaking!

[Richard] Yeah, right,
nobody likes a know-it-all.

[electricity crackles]

Whether we're watching TV,
having a delicious meal,

or developing a revolutionary theory
on particle dynamics,

there is a very strong possibility

that you'll be doing it
whilst sitting down.

In years gone by,
sitting down was a challenge,

but with the invention of the chair,

our backsides
finally had somewhere to rest,

but they're only designed
to accommodate one bottom.

[screaming]

Not two.

[screaming]

Now, I know you'll want to race ahead

and look into
the scientific technicalities

of cushions and footstools,

but let's take it one step
at a time by settling down

with the science of sitting on chairs.

Sitting on a chair with four legs,

it's easy for our man to keep balanced

by ensuring his center of mass
is above his base of support.

Leaning back on his chair,

he has significantly reduced
his base of support

and has created a pivot point
at the base of the chair legs.

When his center of gravity moves outside

this tiny base of support,

the force of his weight
generates a turning effect

around the pivot point,
rotating him backwards.

Thus if you wish to remain seated,

the key is to keep you chair legs
rooted firmly to the ground.

This funky bar stool only has one leg,

which is fine for stroking Tiddles,

but not when you're doing that.

Whatever that actually was.

As soon as the music began,

she twisted her base of support
out from under her,

and gravity took over.

You see, higher chairs are less stable
than lower chairs.

[laughter]

Did he get it?

Falling from a higher chair
meant the foodie

hit the floor with more force

than if he'd opted for a less
fancy restaurant with regular chairs.

Like the chair this couple are using
to get to know each other...

intimately?

Their combined center of gravity
tipped the chair forward,

creating a turning effect
around the front legs.

That's enough, you two, get a room.

[glass shatters]

[electricity crackling]

[glass shatters]

And that brings us to the sticky end
of this Science of Stupid,

but before I go, if imitation
is the sincerest form of flattery,

then I sincerely ask you not to imitate
these brave scientists,

as you could well end up flattened.

Goodbye.

[groans]

[bone cracks]

[man, off-screen] Ohh!

[screams]

[groans]

[screams]