04x03 - Tyres, Monster Trucks and Scooters

[bunniefuu]

[Dallas] This is the Science of Stupid.

[reading]

Yes, this is the show

where intelligence and idiocy are combined

as our determined daredevils
risk life and limb

in the pursuit of scientific knowledge.

We'll reveal what went wrong and why

with the help of some
fundamental laws of science

such as resultant force,

hydrodynamic drag,

and neutralization reactions.

There can only be one winner

in the battle between science
and stupidity.

So don't be a loser.

Watch out. It's the Science of Stupid.

In this show, we'll be looking at...

Aah!

[Dallas] Kinetic friction,

Newton's second law...

[screams]

[Dallas] And transparency.

But first this.

Here at the headquarters
of Science of Stupid,

we've had some new gates
fitted on the entrance road

to our massive compound.

Unfortunately, they haven't
gone down too well

with everyone on our team.

Look, there's Bob from Accounts.

[grunts]

[Dallas] Oh, he'll be in a mood all day.

Oh, Mickey from the post room.

Never one to rush.

Yeah, that'll teach him.

It should be so easy.

You just put your ticket in

and drive on through, like that.

[crashing]

Not like that.

These obstinate obstacles
are called boom barriers,

and while they may exploit
human stupidity,

that's not their intended purpose.

So how do they work?

Boom barriers act as lever arms

that pivot around
a single attachment point.

A force applied to the boom
can create a turning effect

that can bend or break it.

And a larger force or one applied further

from the pivot can increase
that turning effect.

A descending boom
has a large linear velocity

at the point furthest from the pivot,

which makes it hard to see
and react to in time.

So those are the basics of boom barriers,

but as they are only notional barriers,

they perhaps don't get
the respect they deserve

in the real world.

This cyclist is riding sensibly

and staying within
the clearly marked cycle lane.

Aah!

[Dallas] This one isn't.

He hits the boom barrier at some speed,

and the force at the end of the lever arm

is enough to knock it off...

-Aah!
-[Dallas] And him down.

I know you've got your Lycra on,

but it's not a race.

Pedestrians should also be vigilant

and pay attention to their surroundings.

-Aah!
[Dallas] Boom... barrier.

As he strides along purposefully,

he's forgotten that
the barrier travels fastest

at the point furthest from the pivot.

-Aah!
-[Dallas] That's good.

He's remembered now.

Going under a boom barrier
clearly has some risks,

but what about going over one?

-[man] One.
-[Dallas] Not bad.

Not good.

On the second jump, he doesn't have enough

vertical velocity to make it over,

and the force of his weight

makes the fragile arm snap off

without any visible resistance...

Just a large bill for criminal damage.

I'm just doing the maths,

and when you're in free fall,
gravity accelerates you

at 22 miles per hour every second.

So if you fall from a height of 15 meters,

you hit the ground at 38 miles per hour,

which would hurt a lot,

and so our testers have been
looking into ways

to reduce their impact force.

Ow!

[Dallas] That still looks painful.

-Jump.
-Oh, oh!

[Dallas] And so does that.

Oh, [bleep]!

Oh!

[Dallas] But that's just really stupid.

These acts of immense stupidity

should not be attempted at home

or anywhere, for that matter.

But what they have in common
is a successful reduction

in impact force using what I like to call

the foliage principle.

Newton's second law tells us
that the shorter

the deceleration time,
the larger the impact force.

The branches on a hedge
are flexible and elastic,

so they decelerate him
over a longer period,

producing a lower impact force.

And a deeper hedge
with more flexible branches

can reduce the impact force further still.

Of course, if you miss the hedge,

you can wave good-bye
to that long impact time,

so it's probably best not to even try it.

[man] Yeah!

Oh!

[Dallas] I see. You're going to anyway.

He aims well, landing
face-first in the bush...

Where the flexible and elastic branches

decelerate him over
a relatively long period...

Aah!

[Dallas] Reducing his impact force.

[laughter]

He's got it.

Aah!

[Dallas] So does he.

[man] Go, man, go.

-Aah!
-Yee-ha! Oh!

[Dallas] But he doesn't,

unless we're talking about broken legs.

The first two jumpers
make it into the tree successfully

and benefit from the gradual deceleration

provided by the branches.

The third guy misses and hits the ground

with a large impact force.

-Yee-ha!
-[thud]

[Dallas] Remember, this is dangerous,

especially when you miss.

Oh! [bleep]!

Even jumping over hedges,
shrubs, and bushes

is riskier than it seems
because, as we've learnt,

contact with foliage can lead
to gradual deceleration,

like this beverage-holding hedge hurdler.

-Oh!
-[laughter]

[Dallas] Oh, I think you spilt a bit.

[laughter]

He lacks sufficient vertical
and horizontal momentum

to clear the obstacle,

so his legs experience a slowing force,

but his top half doesn't...

-[man] Ooh!
-[Dallas] So he loses face

-and loses his drink all at the same time.
-[howling laughter]

Perhaps a bigger run-up would help.

[screams]

-[Dallas] Ah, maybe not.
-I'm OK.

[Dallas] While she clears
the hedge itself,

her feet hit a plant on landing

and experience some deceleration.

Luckily, that table was there
to slow her down

before she hurt herself.

I'm OK, I'm OK!

There's nothing more relaxing
than a spot of gardening,

but can you guess
which scientific principle

this teetering tree surgeon
is about to demonstrate?

[Dallas] We asked you what science

this amateur lumbering lumberjack

was going to show us.

Aah!

[Dallas] Did you say pivot points?

Spot on.

Because the branch is still attached

at its base, it pivots, falling in an arc

rather than straight down.

Hitting the ground, the end digs in,
creating a new pivot that makes the branch

arc back towards the ladder,

knocking it out from under him

and leaving gravity to bring him back
to the root of his problem,

literally.

[clattering]

Skateboarding is what's known
as an extreme sport,

and if you ignore the science,
it can be extremely painful,

especially if you want to stop.

-Whoo-hoo-hoo!
-Oh!

[Dallas] Crash!

-Aah!
[Dallas] Bang!

Wallop!

And a splash for luck.

[man] Oh, my God!

Yeah, putting on the brakes
when there are no brakes

can be tricky,

so let's find out the best way
to stop a skateboard.

Traveling forwards on the board,

his momentum is only resisted

by a small rolling
resistance at the wheels.

To initiate the stop,
he turns the board 90 degrees

by swiveling his hips

and pushing more with his rear foot

and squatting down using
his quads and core muscles.

His momentum keeps him moving forwards,

but as the wheels start sliding,

kinetic friction applies
a slowing force to the wheels

so he can come to a controlled stop.

So that's the science,
but how will our testers fare

when they attempt
to put it all into practice?

He's going fast.

I wonder if he's been paying attention.

Aah!

[Dallas] And that will be a no.

With a fast descent adding complexity,

the rider doesn't squat enough
to reduce the turning force

from his momentum

and the wheels' kinetic friction...

So he's flung forward at high velocity.

And that's why we wear a helmet.

I wonder if this dude has got it.

That's pretty cool.

Oh! Ooh!

-[Dallas] Not so cool.
-Ooh!

[Dallas] This rider gets
almost everything right,

with a good squat and strong quad action

to resist the turning force.

Oh! Ooh!

[Dallas] Shame about the bike.

Ooh!

[Dallas] Good.

Whoo-hoo!

[Dallas] Better.

Aah!

[Dallas] Worse.

Rider one over-rotates
but manages to keep control.

Rider two executes a perfect stop.

And rider three under-rotates his board,

so it changes direction
rather than sliding...

While his momentum
keeps him going straight.

Aah!

[Dallas]
But whatever happens, don't do this.

Argh!

[Dallas] You will stop quickly,
but you'll wish you hadn't.

Aah!

[school bell rings]

It's that time when I need you to sit up,

concentrate, and pay a bit more attention

and hopefully you'll become
a little better educated too.

Yes, it's the Science Lesson,

and today's key scientific principle

is shared by the following three things...

this birthday clubber...

Oh!

[Dallas] This enthusiastic bonfire.

[man] Oh!

[Dallas] And this careless puddle jumper.

[man] Yeah!

[Dallas] Oh, he'll have lovely skin.

[laughter]

If you said that all of these

contained examples of light's
interaction with matter,

then give yourself a pat on the back.

So it's pens at the ready
and prepare to be illuminated

as we learn all about light.

Fermat's principle tells us
that beams of light

travel in straight lines

and light interacts with objects

differently depending
on their material properties.

We see an object like this basketball

when light is reflected
from its surface into our eyes.

Smooth reflective surfaces
like this mirror ball

produce specular reflections
that can form images

of the object in front of them.

And this transparent glass box
allows some light

to be transmitted
so it passes straight through.

I hope you all found that enlightening,

because, quite frankly,
I don't want you looking stupid.

Right, question one...

what interactions of light
can make perceiving objects difficult?

Ah, here's little Johnny,

one of our senior researchers.

Can he figure it out?

No.

A mirror maze has mirrors
that reflect light

and transparent panes
that let it pass through,

creating a complex visual illusion...

And a sore nose.

Question two, how do you spot
a transparent material?

Sometimes when you're running for a bus,

it feels like there's an invisible barrier

holding you back.

-Oh!
-[Dallas] But you've just

gotta smash through it and carry on.

The transparent glass
lets light pass through,

and our rushing runner is moving too fast

to notice the subtle visual clues...

Like the brackets holding the glass.

Oh!

[Dallas] Still, at least he got the bus.

And now we come
to our third and final question.

What happens when you add more energy

to a luminous source?

There's nothing quite like
relaxing around a campfire

with your friends on a dark night.

-Oh, my God!
-Aah!

[Dallas] And this is nothing like that.

Adding more fuel creates more combustion,

thus emitting more light energy...

Aah!

[Dallas] And giant flames,

which then set that girl on fire.

There was something I was gonna tell you.

Oh, yes, don't do it.

Class dismissed.

Just recently,
I've been suffering from really,

really sore feet, so some of our testers

have been doing some research

into ways I could alleviate the pain.

That wasn't what I had in mind.

No, neither was that.

I can think of better ways to eat nuts.

I don't think this is gonna work.

Aah!

While I am grateful for the work
our testers are doing,

I'm not convinced
that walking on my hands

was the answer I was looking for.

For one thing, I am awful
at texting with my feet.

But the science is fascinating.

First he needs to push off
against the ground,

generating vertical and angular momentum.

For stability, his center of mass

should be vertically aligned
with his shoulder joints.

By walking on his hands, he generates
more horizontal and vertical momentum,

which he can control
by using a wide hand stance

that utilizes his deltoid muscles,

helps support the shoulder joints,

and can provide the extra force required.

To sum up, you need to be strong
and have excellent technique,

because otherwise you're gonna
end up looking very stupid.

The first steps to get into position.

Not that position.

[groans]

[Dallas] As he pushes up,

his foot gets caught on those blocks.

Then his legs gain too much momentum

in the wrong direction...
-Aah!

[Dallas] Which his body tension
is unable to counteract.

But his face is.

[groans]

[Dallas] That is a much better technique.

Now it's all about controlling
his center of mass

and using his strength.

Or maybe not.

As his muscles tire,
his left wrist buckles...

and then his right wrist stutters...

while his legs keep going.

Aah!

[Dallas] But at least he'll have

some dry shoes to put on
for his walk home.

It's also important to make sure
you don't get distracted.

I'm going that way. I'm going that way.

[man] Yeah, you're looking at...

-Ow!
-[cat meows]

[Dallas] The boy's legs
have forward momentum,

but by walking on his hands,
his upper body keeps upright.

But then the cat moves,
causing a slight distraction...

Ow!

[Dallas] And giving him
a close-up view of the carpet.

[cat meows]

And remember,
you've got to learn to walk...

-Oh, my God!
-Oh!

[Dallas] Before you can run.

[engine revving]

Whenever I have to move a heavy object,

I always have the same dilemma,

push or pull, what's better?

As always, I go to the animal
kingdom for inspiration.

The muscles in monkeys' hands
mean they're well adapted

for grabbing and pulling...

[laughs]

[Dallas laughs] Like that.

Cheeky.

Humans are also good at pulling.

Well, sometimes.

OK, let it rip.

[Dallas] And we can also push, which
comes in handy for broken-down cars.

-Stop!
-[laughs]

[Dallas] But we can't push
anywhere near as well

as this rhino.

I'm not sure that car was broken.

Don't worry. He was OK.

In fact, that horn
had barely a scratch on it.

Whether an animal is good
at pushing or pulling

will depend on a variety of factors,

but what should give humans the edge

is understanding the science.

Pushing is simpler than pulling,

as it doesn't require
a grip on the object itself.

Using the whole body means
that the force is delivered

by a larger number of muscles,

and the same strong muscles that are used

in the course of locomotion
are used for pushing forwards.

In order to successfully pull an object,

an animal needs to have sufficient grip

to hold on to it,

enough muscular strength
to apply the force with,

and, like when pushing,

enough traction with the ground

to withstand the reaction force

that can make them slip.

So there's the science,

but how does that work in practice?

This cat is auditioning for the role

of an evil villain's pet.

[woman] No, no, no, no, no!

No, no, no, no!

No.

No.

[shattering]

[Dallas] Hashtag: SmashedIt.

The cat goes for a one-limbed approach,

using front leg muscles
to move the glass with ease

due to its low weight

and low friction with the table.

[shattering]

This pig is a little camera-shy.

And this is life-- Aah!

[Dallas] I did warn you.

Are you OK?

[Dallas] The pig uses muscles in its neck
to exert a force with its head

-and push the man backwards...
-Aah!

...exploiting his unstable position...

[grunts]

...and making the man

rethink his dream
of joining the paparazzi.

Now, is this dog
pushing or pulling the cart?

[woman] Rocky, stop! Ah!

-[Dallas] Whatever he's doing...
-Rocky!

...it's made a lot of mess.

Because the cart is hitched
to the dog's collar,

he's actually pushing on the collar,

and it is this force
that makes the cart move.

[woman] Rocky, stop! Ah! Rocky!

[Dallas] I don't think they'll
be doing that again now.

That's all for now, and I hope
you've been paying attention.

Thomas Huxley once said,

"Science is simply
common sense at its best."

He clearly hasn't been watching this show.

Aah!

[grunts]

-Oh!
-Aah!

-Whoo-hoo-hoo!
-Oh!

Aah!

Oh!

Aah!

Oh!

Argh!