07x01 - Black Ice, Blenders and Inflatables

[bunniefuu]

[Dallas Cambell]
This is the Science of Stupid.

[klaxon blaring]

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

[man, beep].

[Dallas] Watch as human guinea pigs
attempt harebrained stunts

and ill-advised activities,

all in the name
of scientific enlightenment.

We'll reveal what went wrong and why

with the help of key principles.

For some, it's friction.

For others, flexural strength.

But for him, definitely gravity.

Fight with physics,
and you're doomed to fail.

Watch out!

It's the Science of Stupid.

[electricity crackling]

In this show, we'll be learning about...

turning effects.

Thermal expansion.

[man screams]

And rotational kinetic energy.

But first, this:

[glass shatters]

[electricity crackling]

[glass shatters]

As you know, we're all about
health and safety here

on the Science of Stupid,
which doesn't always sit comfortably

with our love of motorbikes.

And that's why we've been searching
for hazard-free

motorcycle-related science for some
time.

And when someone suggested
walking along with your bike,

I thought we'd cracked it.

[engine revving]

That was before I was made aware
of this experiment

conducted by some
of our younger researchers.

[laughter]

Okay, there's clearly
something going on here,

and in times of need,
we must turn to the science

behind what's known
as "walking a motorcycle."

Our man twists the throttle
very slightly to inch forward.

Too much throttle,

and the induced torque in the back wheel

will make the bike lurch forward.

The natural reaction is to hold on.

But this makes him twist
the throttle even further,

causing the bike to accelerate more.

It's known as a positive feedback.

The increased torque on the back wheel
can lift the front wheel and...

[motorcycle crashes]

Who'd have thought there'd be
so much potential peril

in something so simple?

At least everyone's been warned now.

[man screams]

Looks as though
someone wasn't listening.

[slow-motion screaming]

Next!

[engine revving]

Hmm, he doesn't strike me
as a seasoned biker,

but appearances can be deceptive...

just not in this case.

[engine revving]

[laughter]

He was given a warning
when he over-throttled

whilst trying to ride the bike,

but the best was still to come.

As the bike pulled away,
he attempted to hold on,

but only succeeded

in twisting the throttle further,

meaning the bike accelerated
faster than he could run.

[laughter]

Positive feedback, eh?

Bit of an odd name in this case.

[laughter]

Right, this looks like it.

These guys work with bikes.

They'll know all about positive
feedback.

-[engine revs]
-[crowd gasps]

Yeah, must be
his first day on the job.

With the scooter heading into the crowd,

his natural reaction is to hold on.

That causes the throttle
to twist even more.

His friend keeps hold of the scooter,

but that just adds an additional force

that increases the torque.

[crowd gasps]

Is everyone okay?
Are you enjoying the show so far?

Hang on, she's a freerunner.
This bit's about motorcycles.

Ah, now I get it.

And she's obviously a scientist as well.

What's more, a scientist who specializes
in positive feedback.

Please don't do that yourself.

[horn honks]

I've no idea why anyone would.

[electricity crackling]

[creaking]

Quick question for you:

what is more treacherous than ice?

It's ice you can't see.

Otherwise known as black ice.

[laughter]

It's a great name, but guess what?

Black ice isn't black.

I think we need some science.

When water freezes,
impurities and air bubbles

can become trapped in the ice.

When light enters the ice,
those bubbles and impurities

reflect and scatter the light,

making it appear white.

But thin ice with
no air bubbles or impurities

is more transparent,
allowing light to pass through

and reflect off the dark
road surface beneath.

This black ice also tends to be
smoother,

providing very little friction
for shoes or tires.

Yes, black ice is very much
the pantomime villain

of meteorology.

Extra slippery and invisible.

It's most likely to form after light
rain

from freezing fog
or melting snow that refreezes.

Basically, when the ice forms
in calmer conditions.

It all feels a bit dangerous,

so let's conduct
our first experiment on foot

before we even think
about getting in the car.

The snow appears to be melting here,

so it could have refrozen
and formed black ice.

It's, uh-- well,
it's hard to tell, really.

[man grunts]

Yeah, yeah,
there's black ice present.

And proof that because it's smooth,

it's very slippery.

[man groans]

Right, we've ascertained
that black ice is very hard to spot.

I wonder if there's any here?

Yes, there is.

This doesn't feel too scary, though.

It does now!

[horn honking]

A thin, transparent layer
of ice has formed,

making it undetectable
from the road's surface,

and the lack of friction
causes a loss of traction.

I do hope he's got a spare pair
of trousers in the boot.

Right, time for round two
of "spot the black ice."

It's transparent,
so it'll look like the rest of the road.

[tires squealing]

Oh, he's found it.

[tires squealing]

And so has he.

Don't worry, they were okay.

All right, we're almost done here.

But I do want to share with you
some words of wisdom

from my dear old granddad.

He always said, "If you see
a man skating on tarmac,

there's probably black ice around."

I never quite understood
what he meant by that,

but it's clear now.

Thanks, Granddad. Wherever you are.

[electricity crackling]

[creaking, crashing]

Right, it's time
for a little science teaser.

Can you guess how physics
is about to liven up

this fire service training exercise?

[sirens wailing]

[glass shatters]

[electricity crackling]

[glass shatters]

[sirens wailing]

[Dallas] Have you worked out
the scientific principle

that's about to dampen the enthusiasm
of this fire engine driver?

[sirens wailing]

[glass shatters]

Yes, that's right. It's inertia.

As the fireman turns the truck sharply,

friction between the wheels and the road
stops the wheels sliding sideways.

But inertia means
its mass wants to continue

in a straight line.

The truck's high center of mass
produces a large turning effect

pivoting it at the wheels.

[glass shatters]

Just as well it wasn't a real fire, eh?

[glass shatters]

[electricity crackling]

[glass shatters]

This, gentle viewer, is a Penny board.

It's the smaller cousin of the
skateboard.

Now, it looks tiny and cute, sure,

but in the wrong hands,
it's a little terror.

[crashing]

[man] So I'm thinking
of buying a Penny board--

[Dallas] I'd take that back
to the kids' section, sir.

Yes, it appears that if you are old
enough

to remember life before the smartphone

and think that flossing
is a dental procedure,

you're probably too old
to be messing about on Penny boards.

The reason why, as ever,
lies in the science.

The Penny board, at the top,
has a shorter wheel base

and track width than
the standard skateboard at the bottom.

Therefore, our Penny-boarder
has a smaller base of support

than the skateboarder.

This makes it harder to balance,

because he has less area

over which to keep
his high center of mass.

Ah, yes, that old classic.

Small base of support,
high center of mass.

Lean a fraction too far, and you're off.

Hit an obstacle, and it's
a catastrophic turning effect.

But don't worry, because as we all know,

small skateboards are designed
for small people,

also known as children.

[woman, off-screen] That skateboard
is way too small for you.

[Dallas] I think she might have a point.

[man] I can skate on anything.

What do you think?
[grunts]

[laughter]

[Dallas] Unless he's big for his age,

I think we're looking
at a middle-aged man here.

When his board, or small base
of support, suddenly stops,

his momentum and high center of, uh,
mass

combine to create a large turning
effect.

Get up and grow up.

This chap looks closer
to skateboarding age,

though he still looks quite big
for that Penny board.

He's clearly done a fair bit
of skateboarding.

[bleep]

But that might
have been at the expense

of his physics class.

This researcher is investigating

whether a static Penny board
is any more stable,

and the results are conclusive.

No. If anything, it's worse.

He hits the board slightly off-center.

His center of mass moves
outside his base of support,

and we're presented with clear evidence

that Penny boards
should be left to the kids.

[laughter]

[man, off-screen] Go.

-[glass shatters]
-[man] Oh!

[Dallas] Just not that kid.

[woman, off-screen] It's alright, it's
OK.

[bell rings]

[glass shatters]

[liquid hissing, bubbling]

[Dallas] Right, settle down, everyone.

Chancellor, take that out of your mouth.

Put it in the bin.

Yes, it's time for today's science
lesson,

where we conduct a thorough examination

of a fascinating scientific principle.

But can you guess what it is
from the following?

[man] I'm using this solar cooker...

to prepare food in a glass pan.

[Dallas] A cracking idea for a barbecue.

[glass shatters]

These chestnuts roasting
on an open, uh, draining board.

[women screaming, laughing]

And a cozy fire.

-[man] Oh!
-[laughter]

[Dallas] If you said "thermal
expansion,"

you have earned yourselves a house
point.

Well done.

Thermal expansion refers
to a change in the volume

of a solid, liquid, or gas
in response to a change in temperature.

Here's a bit more detail.

Heat a wine glass, and its particles
move further away from each other.

Because the heat is unevenly
distributed,

thermal stress occurs, and...

Conversely, when this heated bowl
is suddenly cooled,

the particles move closer together.

And because it's cooled unevenly,

thermal stresses occur.

Gases like the steam inside this can

have molecules that are
weakly attracted to each other,

so when heated, they expand
more than liquids and solids.

And when cooled...

contract more.

Okay, let us see who's been listening.

Question one: what happens
to a material when it's heated?

[glass shatters]

That's right, it expands.

As he heats the neck of the bottle,

the particles separate,
and the glass expands.

Because the heating is uneven
and glass is brittle,

thermal shock occurs.

[glass shatters]

This footage actually comes
from a documentary called

Why the Corkscrew Was Invented.

Quite good film, actually.

Right, question number two:

do liquids experience thermal expansion?

The can of beans
boiling gently on that fire

should give the answer.

[screaming, laughter]

Yes, liquids do experience
thermal expansion.

The sauce in the can
expands as it's heated,

increasing the pressure inside.

The can's material strength
is exceeded, and...

[screaming, laughter]

That completely missed my plate.

Right, third and final question:

does a gas expand more or less

than a solid or liquid when heated?

That's right, it's more.

As the air in the balloon
is heated, it expands,

decreasing its density.

As the air is less dense
than the air outside,

buoyant force is created.

[man, off-screen] Ai-yi-yi-yi-yi.

[man screams]

[Dallas] Just not enough in this case.

They were all fine,
but they just like to go

for a nice walk on a Sunday afternoon
now.

Well, that's thermal expansion for you.

[man screams]

[Dallas] More dangerous than it sounds.

Class dismissed.

[glass shatters]

[electricity crackling]

[Dallas] There are many reasons
why I have feelings

of intense jealousy towards
people younger than me.

Their taut, athletic bodies,

their line-free faces,

and their hope.

But if there's one thing
I resent more than any other,

it's their choice of inflatables.

I had an old Lilo.

They've got these.

Blobs.

Giant air-filled cushions

anchored in a lake or the sea

provide hours of fun
for healthy young individuals

with disposable incomes
and plenty of free time.

They make me sick.

[splashing]

-[man] Whoo!
-[crowd cheering]

[Dallas] But I'm delighted to report

that Blobbing doesn't always go to plan.

[woman gasps]

[laughter]

Yes, there's clearly more
to catapulting your friends

by means of giant inflatables

than meets the eye.

As ever, the complexities lie
in the science.

Up high, our leaper has
gravitational potential energy.

As he falls, that energy
is converted to kinetic energy,

which is transferred
via the air in the bag to his friend.

It's the law of conservation of energy.

But the flier must be
perfectly positioned.

Too far forwards
and too much horizontal velocity

will make his
parabolic trajectory too flat.

Too far back
and excessive vertical velocity

will make that trajectory too steep.

But let's not worry
about trajectory for now.

Let's start with that transfer of
energy,

or to give it a technical term,
jumping on the Blob.

Here we go.

[both scream]

And there she went.

Her failure to land properly

means she transfers
very little kinetic energy to the Blob,

which means not enough kinetic energy
is transferred to her friend,

who could have had
as much fun sitting down in a puddle.

[both scream]

[man, off-screen] Five, four...

[Dallas] Ah, will three jumpers
do the trick?

[Dallas] They certainly will.

-[man screams]
-[laughter]

Three chaps falling
from a height means plenty

of gravitational potential energy

is converted to kinetic energy
as they fall.

That energy is transferred to their
friend through the air in the Blob,

and before you know it,

he has his own
gravitational potential energy

ready to be converted back
to kinetic energy.

[man screams]

A conclusive
and successful experiment.

Though he may see things
slightly differently.

[laughter]

Right, we seem to have mastered
the conservation of energy,

so let's move on to
the all-important parabolic trajectory.

Now, what did we say happens

when you sit too far forward on the
Blob?

-[man grunts]
-[girl shrieks]

Oh, yes, that's right.

Your parabolic trajectory
has too much horizontal velocity.

Let's move back a bit.

[man screams]

-[Dallas] I didn't mean that far.
-[woman, off-screen] Oh!

[Dallas] By moving too far back,

our aquatic researcher gained
too much vertical velocity

and virtually no horizontal velocity.

-[man screams]
-[woman, off-screen] Oh!

[Dallas] As I'm sure
his friends will politely explain

to him later.

[electricity crackling]

[creaking, crashing]

Do you no longer trust
your own body's digestive system?

Too busy to eat food
and wait for your gut to break it down?

Then get yourself a blender or juicer.

But be warned.

[woman, off-screen] I tried to make...

tzatziki.

But it got...

a little...

out...

of hand.

Oh my God.

[Dallas] Yes, the humble blender
needs to be treated with respect.

To understand why, you need
to get your head around the science.

The spinning blades create a vortex,

drawing the contents downwards
in a spiral in the middle.

The blades have rotational kinetic
energy

and apply a shear force
that cuts the food into small pieces

and also pushes it up the sides.

With some blenders, if you overfill
or fail to secure the lid properly,

then the upward force of the vortex

can overcome
the frictional force of the seal.

Worse still, leave the lid off
completely and, yeah.

It's a big no-no.

The largest blender ever
stood 16 feet tall,

and it was used to make
a 350-gallon smoothie.

So someone definitely got
their vitamin C that day.

Given the spilly potential
of rotational kinetic energy,

let's start with something
a little smaller.

Yep, that'll do.

[whirring]

Bit full, maybe?

-[woman shouts]
-Definitely.

As the spinning blades pulverize the
food,

they create a vortex
that drags food into the center

and then pushes it up the sides.

Because the blender was so full,

that upward force overcomes
the frictional forces

that seal the lid.

Textbook.

Ah, not full to the brim.

Good thinking...

if you'd secured the lid properly.

Remember, badly secured lid

equals very little frictional force

to resist all that
rotational kinetic energy.

Assuming you remember to secure the lid

and don't overfill your blender,

there's one thing to remember,
and it's this:

put food and only food in it.

This is an experiment conducted
by Henry from computer science.

Oh, we had such high hopes for him.

I need to get him in for a little chat.

I'll, I'll call him now.

Ah, no point. He hasn't got a phone.

[electricity crackling]

[glass shatters]

Well, that is it
for this rather chaotic stumble

through the world of practical science.

Albert Einstein once said,

"Failure is success in progress."

Well, Albert, this lot
have a long way to go.

[laughter]

[horn honking]

[laughter]

[screaming, laughter]

[man, off-screen] ...yi-yi.

[man screams]

[both scream]

-[glass shatters]
-[man, off-screen] Oh!

[man screams]

-[man screams]
-[woman, off-screen] Oh!