05x14 - Chairs, Cars and Unicycles

[bunniefuu]

[Dallas] This is the Science of Stupid.

[Dallas] Yes.

This is the show where aptitude and
absurdity amalgamate

in a cacophony of catastrophe.

As our rash researchers investigate key
scientific principles,

so you don't have to.

With our expert assistance,

we'll scrutinize the science behind
transfer of momentum.

Access of rotation.

[screams]

[Dallas] And Young's modulus.

So, thinking on caps on,
it's time to get educated,

because this is
the Science of Stupid.

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

Stability.

And hand eye coordination.

Or the lack of it.

But first this.

There's nothing I love
more than a trip to the beach.

Sun, sea and sand are the
things dreams are made of.

But it's when you start to relax that
those dreams can turn to nightmares.

[Dallas] Because even when you're
chilling out, you can never

let your guard down.

That giggle with your girlfriends might be
funnier than you expected.

[screams]

[Dallas] And of course, if your
mum starts dancing.

[screams]

[Dallas] Keep your distance.

The sun and the sea are both well-known
for their risks,

so today, we're gonna focus on
that lesser known evil, sand.

[Dallas] When walking or running, our man
relies on vertical reaction

forces, that keep him from sinking and
horizontal frictional forces from the

ground, which
propel him forwards.

But sand is granular, so the particles
easily slip past each other,

meaning he
generates less force.

Sand is also likely to form uneven
terrain, with lots of trip hazards

and running down
hill is even harder,

because a component of his weight tries
to rotate him over.

When I'm on the beach, I prefer to stick
to my sun lounger,

but some people are a
little more adventurous.

[Dallas] This man has chosen to
dual with the waves,

as the tide comes in, but has he included
the sand in his escape calculations?

Oh my God.

[Dallas] Apparently not.

As he tries to outrun the water, there's
little reaction force from the sand

and the apex of the
slope catches him out.

And he's going home soggy.

This guy is all decked out
for a day in the desert,

so he should be
fine on the sand.

But you can never
successfully skip in sandals.

As he heads downhill, the fine sand means

his feet struggle to keep up
with his momentum.

He attempts to counter this,
by skipping with long strides,

but his feet dig into the
sand and he takes a tumble.

Luckily, that truck was there to stop him,
before he hurt himself.

This guy is about to launch a paper
airplane from the top of a sandy hill.

OK. Make sure
you don't miss this.

I got it!

[Dallas] I'm
fairly sure this will be epic.

And I was right.

With a downhill run up, his feet are
struggling to keep up with his momentum

and he makes it worse, by flinging himself
forwards in the throw.

[woman] You want to try
it again or are you good?

I'm OK.

[Dallas]
It's probably for the best.

We've seen how walking and running on
sand can be problematic.

But is cycling
down it any better.

I bet you're
going to fall off.

-[boy] I won't.
-[Dallas] I think she's right.

I told you!

[Dallas] Yeah, but
no one likes a know it all.

Did you know that doctors have discovered
a food that causes grief and misery,

years after it's been eaten.

It's called wedding cake, but for some
people, it causes misery and grief

before it's even been consumed.

[Dallas] Especially if kids
are doing the carrying.

Careful guys.
Watch your step!

[Dallas] Fortunately, that
was a joke cake.

Unfortunately, that wasn't.

A delicate touch is key.

[screams]

[Dallas] Something
this groom is sadly lacking.

So, you've got
hitched without a hitch.

You're probably thinking that you've
avoided all the early marital mishaps

and it's plain sailing
from here on in.

But you've forgotten
one thing, the cake.

For a stable multi-tiered
wedding cake, it's center of

mass should be well
within its base of support.

But if pillars are added,

the structure will be less stable, because
the individual

stability of each pillar
has to be taken into account.

Even a slight sideways force
could cause the weight

that each pillar
supports to move

outside their base of
support, making them tilt.

Cutting a cake applies
additional downward force,

so the surface
its sitting on

must be able to
withstand this extra force.

Don't forget that the structure the cake
is on needs to be at least as stable as

the cake itself, or it'll be even more
susceptible to collapse and calamity.

[Dallas] This
looks like a funky wedding.

And that groovy groomsman certainly
knows how to draw attention to himself.

But I'm not sure that's the kind of
attention he was looking for.

The cake has only two tiers, so it's quite
stable, but the table

is essentially one large pillar,
making it much less so.

Therefore, it doesn't need a
very big tilt to take it down.

[screams]

[Dallas] This couple have made
it to the cake cutting,

so their wedding day
worries are almost over.

[laughter]

[Dallas] Well, I did say almost.

When they cut a slice, everything seems
fine, but they're not aware that the

cake's stability
has been affected.

As it topples, the bride applies a
sideways force,

which makes the pillars all

tilt and the structure collapses
into a delicious mess.

Now, that is a beautiful five
tier wedding cake and wisely,

there's not a pillar in sight.

But I'm not sure I like
the look of that table.

Quick, three second rule.

Someone's pleased with their present,
but can you guess what science

we're about to see?

[Dallas] We asked you what
scientific principle

we were about
to see in action.

[screams]

[Dallas] It was of course,
inverted pendulums.

When she mounts the hoverboard, she
becomes an unstable inverted pendulum.

To keep her balanced,
the hoverboard accelerates to

bring her center of
mass back over the wheels.

Unfortunately, she keeps
leaning and ends up running

out of space before the
hoverboard can do its job.

[Dallas] And Christmas is ruined.

Just another reason to be
careful on hoverboards.

Humans are incredibly social and
when it comes to greetings,

we've been coming up with new and
exciting methods for saying hi or bye

since the dawn of time.

Some will get you arrested.

[Dallas] These two were bored of shaking
hands and felt uncomfortable

kissing, so came up with this rather
complicated high five instead.

Sadly, not all high fives are
ex*cuted with such precision.

Surfers are more famous for
hanging ten than highing five.

And you can see why.

At least he looks prepared.

[woman] Oh!

[Dallas] Just not for that.

The elevated hand slap, or as the kids
call it, the high five,

is achieved when two palms crash together
with a sudden stop in the middle.

Sounds simple?

Let's have a look.

[Dallas] As they run towards each other,
their bodies and hands

build speed and momentum.

Hand eye coordination is needed to judge
the hands' trajectories through the air.

At the point of impact, their hands apply
equal and opposite forces on each other.

Making the high
five symmetrical.

I bet, whoever invented the high five was
left hanging a lot in the

first couple of early years.

But it has taken off,

so let's put theory into practice and what
better place to start

than at a high
spirited pool party.

[Dallas] With good
timing and excellent rotation,

their palms connect in a short-lived and
symmetrical impact,

creating a shockwave in the air that we
hear as a sharp crack.

[Dallas] Now, let's see how
their girlfriends do.

That didn't go so well.

The girl on the left is
lacking commitment,

while the girl on the right is not.

Her hand's momentum is dissipated in a
short space of time as she connects.

With her friend's face.

This snowboarder is about to attempt an
extreme high five with his friend.

This should be awesome.

Yeah!

[Dallas] And by that I mean awful.

His trajectory is too low and as he flips,

he can't see the target hand
of his friend.

So his hand eye coordination can't help
him and an awesome stunt

turns into an epic fail.

Jones, stop drawing on
your desk and pay attention.

Yes, it's time for today's science lesson,
that bit of the show where we examine one

scientific principle,
hence the silly hat.

So let's see if you can guess what links
these three individuals.

[Dallas] This experimental skater.

OK.

[Dallas] This backyard acrobat.

And this funfair.

Failure.

If you said the law of conservation of
angular momentum, well done.

Now, let's take a
closer look at the science.

[Dallas] He applies a turning
force, or torque,

to the devil stick,
generating angular momentum.

To make the stick change
direction, he supplies an

opposite torque to it,
with the other hand.

Otherwise it will keep
rotating the same way,

as its angular
momentum is conserved.

With lots of mass distributed
far from it's center,

the stick has a relatively high

moment of inertia, so rotates
with low angular velocity,

making it easier to control.

Do you think you've got it?

Let's see.

Question one, how do you
generate angular momentum?

[Dallas] The answer, of course.

Is by applying a
torque over time.

He leaves the jump with
close to no angular momentum,

but the force from his
collision with the obstacle

is not aligned with
his center of mass,

so it applies a torque on him,
generating angular momentum.

It's quite a walk back
to your skis, isn't it?

Ah, there's nothing like a trust fall to
illustrate the laws of physics.

But before commencing,
consider the consequences.

You're fine. You're fine.

Oh!

[Dallas] He's fine, but you're not.

When he leans backwards,

torque is generated about his feet and
because the catchers

fail to absorb his
angular momentum,

some of it
transfers to them.

[Dallas] Ah, Christmas memories
to treasure forever.

Question two, once
you have angular momentum,

is it possible to lose it, without help?

[Dallas] This girl is going to find out.

Do it, do it.

Oh! Oh!

[Dallas] That'll be a no.

It's always a bad idea
to jump off a bridge.

The girl puts her center of mass outside
her base, so as he jumps,

she generates a torque
and gains angular momentum.

But without any additional torque, there's
nothing to stop her rotating painfully

into the water.

Question number three.

We all know you can't change angular
momentum without torque,

but is it possible to
change your angular velocity?

[Dallas] Yes, you can.

Just not like that.

The first guy tucks in, decreasing his
moment of inertia,

which accelerates his rotation.

As he untucks, his moment of inertia
increases and he slows down.

The second guy doesn't tuck in, so can't
increase his angular velocity

to make a full rotation.

[Dallas] Well, that's the conservation of
angular momentum.

Fun stuff.

Class dismissed.

Yesterday, I was riding a horse at full
speed, whilst being chased by a lion,

it was terrifying.

I felt a lot better
when I got off that carousel.

That was more than enough for me, but for
some, riding isn't limited

to the high jinx at the funfair.

[Dallas] You could cruise on a camel.

Or travel on a tortoise.

Maybe a horse
could be for you.

[screams]

[Dallas] But it's definitely not for her.

Evidently, riding is not that easy
and unlike humans,

other animals don't rely
on saddles and stirrups.

[Dallas] An animal needs to
tense parts of their body

to hang on when riding.

Muscle tension without actually moving the
joints is called isometric contraction.

But the right amount of
contraction is needed.

Too much will lead to a hard ride, too
little and the animal will fall off.

Relative size is
also important.

A quadruped provides more surface area
to sit on, which will provide

more stability for the rider.

And the smaller the rider, the less impact
they'll have on the animal being ridden.

Of course, how willing an animal is to be
ridden will also have a significant

bearing on how things turn out.

[Dallas] This baby alpaca is keen to go
for a ride on its mum's back.

Sadly, mum is less keen.

The young alpaca can't
grip or balance properly,

as it doesn't posses
grasping appendages.

So instead of a ride, it gets a lesson in
Newton's Universal Law of Gravitation.

This dog's relatively large surface area
should provide plenty of

stability for a small frog.

But it's not easy being green, especially
if you're riding a dog.

This pug is more of an
easy rider, looking good.

Just watch out for haters.

[Dallas] When the green eyed growler
jumps up on the bike,

he causes it to tilt, which moves the
combined center of mass

outside the base of support.

He didn't choose the
pug life, it chose him.

I love water sports.

There's nothing better than watching
people get wet while I stay dry.

Which is why I'm so
keen on the kayak slalom.

[Dallas] People have been doing
it since black and white.

But he still needs more practice.

And so does he.

Clearly, this is a highly skilled pursuit
and, as with so many things,

the secret to success
is knowing how to steer.

[Dallas] When our man pushes his
paddle against the water,

it generates reaction forces that allow
him to move forwards and steer.

But these reaction forces are being
applied to the paddle, not the boat,

so he needs to transfer
them through his body.

He does this with a rigid arm
and body position and bracing

himself against the
boat with his feet.

Allowing him to
slalom speedily.

Hopefully, that little bit of science will
go a long way in helping

you stay shipshape in even
the slipperiest slalom.

[Dallas] The guy in the yellow kayak has
excellent steering technique,

as he navigates these rapids.

[screams]

[Dallas] The guy
in the green kayak, less so.

He fails to achieve the necessary reaction
forces with his paddle to steer around the

eddy and winds up
in the whirlpool.

Don't worry, he
escaped, eventually.

These three look like experienced kayakers
playing with the currents

-in this swollen river.
-Go for it, Tom.

[Dallas] But even if you know what
you're doing, you need to be

careful of unfamiliar waters.

[screams]

[bleep]

[Dallas] So something like
that doesn't happen.

Don't worry, he was fine,
a little dizzy, but fine.

Even the best can experience difficulties
in extreme currents.

But if that does happen, at least the
worst of your problems are behind you.

Ah.

This guy can't generate sufficient

reaction forces to rotate the kayak out of

trouble and just when it seems like things
can't get any worse.

Things get worse.

Maybe it's best to stick
to something a little more

sedate, like fishing.

[Dallas] Yes, much better.

Well, that's all for now, but I will leave
you with this final thought,

that possibly came
from Benjamin Franklyn.

We are all born ignorant, but one must
work hard to remain stupid.

[music plays through credits]

[screams]

♪ ♪