04x12 - Pogo Sticks, Drumming, and Snowdrifts.

[bunniefuu]

[Dallas]
This is the Science of Stupid.

[reading]

Yes...

this is the show that celebrates flops...

and failures...

and explains the science
behind their actions...

with the help of some serious stupidity.

-There'll be smacks...
-Hi-yah!

...cracks...

and whacks...

so get your brains in order,

because we'll be examining
key scientific principles

-such as...
-Aah!

-...forward momentum...
-Aah!

Rotation...

and ground reaction force.

In the battle between
science and stupidity...

-[man] Oh [bleep]!
-there's only ever one winner.

So don't try any of this at home.

-[crash]
-It's much safer that way.

-This is the...
-Oh!

...Science of Stupid.

[electricity crackling]

-[lively banjo music]
-In this show,

we'll be looking at tensile strength...

[all scream]

-Drag...
- [woman screams]

And resultant force.

Aah!

But first this.

[electricity crackling]

I love a bit of winter sport action.

The thrill and excitement
of racing downhill

is hard to replicate,

and these days snowboarding
has become rather popular

with people searching for a bit of fun.

Unfortunately, they don't always
find what they're looking for.

[lively music]

He's looking for his mates.

-[whack]
-[man] Oh!

[Dallas] Oh, and he's found them.

He's looking for peace.

-[laughing]
-[Dallas] It's not down there.

And he is looking for trouble.

Oh!

Mission accomplished.

To prevent these crashes
happening to you on the slopes,

it always helps to have an understanding

of how the science of
downhill snowboarding actually works.

So why don't we take a look?

When snowboarding downhill,

a component of gravity accelerates
his center of mass down the slope.

The steeper the slope,
the faster he'll accelerate,

and the more momentum he'll build.

A low coefficient of friction
between board and snow

also helps him build momentum,

as long as the upturned
end faces forwards.

But if the snowboard digs in,

friction will suddenly
increase at his feet,

sending him flying.

Well, it's time to put
all that scientific insight into practice,

so wrap up warm,
because it's all downhill from here.

[lively music]

Remember, the quickest route
isn't always the safest.

And if the unexpected happens,
you've just got to roll with it.

[man grunting]

When his snowboard
digs into the fluffy snow,

the extra friction
increases the slowing force at his feet,

which combines with the momentum
of his body to rotate him forward.

And the steep slope
keeps him accelerating downhill,

increasing his momentum
and enhancing that tumble.

He was fine, but I think he'll struggle
to find that contact lens!

[rock music]

This ambitious snowboarder
is ready to face his fears.

-Ooh!
-And that's his fears faced.

As he approaches the jump,
he turns the board sideways,

making it dig into the snow.

The sudden increase in frictional force

makes him rotate in the air
before landing.

-Ooh!
-A perfect face plant.

When riding downhill, it's also important

to be aware of sudden changes
in the terrain...

or that might happen.

[man] You landed it!

[Dallas] His forward momentum,
combined with increased frictional force

as the board digs in,
sends him rotating forwards.

[man] You landed it!

[Dallas] That's one way of describing it.

Whoo!

And, if you must use a selfie stick,

try to focus on where you're going
and not how you're looking.

Looking pretty foolish now.

[electricity crackling]

[engine revving]

I've always found
that bridges are particularly useful

for crossing any physical obstacles
like rivers or roads.

But for the foolhardy, they're also
launch pads into a world of pain.

[lively music]

That will hurt.

Yep. He's got it.

Him, less so.

If you are going to bridge jump...

[laughter]

Make sure there's some water
underneath it.

[laughter]

As our fearless friends have just proved,

flipping off a bridge
is potentially painful,

very stupid, and incredibly dangerous,

and here's some science
to help you understand why.

To start a flip,

he pushes off with his center of mass
leaned over the edge,

generating angular momentum.

When our man enters the river,

the drag force from the water
slows him down.

To minimize drag, he needs to enter
the water with a streamlined shape,

with as small a frontal surface area
as possible.

But under or over-rotate, and he'll flop,
generating a much larger drag force

and much, much more pain.

As you've just learned, flipping off
a bridge is a complicated business

and ignoring the science will
inevitably lead to pain and humiliation.

Sadly, some people's reckless ambition
knows no bounds.

[upbeat music]

I've got a bad feeling about this.

[man] Whoo-hoo-hoo-hoo!

[Dallas] He's got an even worse feeling.

Going for the triple flip,
our foolish friend under-rotates,

and a lack of streamlining
from his massive back flop

results in a lot of drag
and a hefty impact.

Has she got it?

[man] Awwww!

Only if we're talking about
a red, sore back.

[man] Are you all right?

-[Dallas] Does she look all right?
-That really hurt, Robert.

Flipping from the bridge, she over-rotates

and fails to adopt
a streamlined body shape,

creating a larger drag force
that decelerates her much more quickly,

producing a larger impact force.

Aah!

Now, she looks a bit more
like a professional.

Aah!

And by professional, I mean amateur.

This bridge flipper fails
to control her jump and over-rotates...

From a height of 50 feet,

she'll hit the water
at nearly 40 miles an hour.

Aah!

Which should be enough
to warn you what a bad idea this is.

Aah!

[crashing, shattering]

What scientific principle are these
rash road workers about to demonstrate?

[glass shattering]

[electricity crackling]

[Dallas]
We asked what scientific principle

these two lousy laborers
were about to show us.

It's torque.

The drill's motor provides a torque

that rotates the bit
relative to the drill head.

The stiff ground
resists the rotation of the bit,

so the construction workers
must resist the rotation of the head.

But when the reaction torque
becomes too great,

the head starts spinning,
taking them with it.

And you wondered why roadworks
always seem to take so long.

[laughing]

Golf is a sport.

It's also one of my favorite pastimes.

Not only does it appeal
to my fashion sense,

it also allows me to pass
on a little common sense.

Like always wear appropriate clothing.

-Oh, no!
-[man laughing]

[Dallas] Like a wetsuit.

Don't forget to keep your eye on the ball.

Ahh!

And always approach a shot
with a can-do attitude.

-Ooh!
-[man] Oh, yes!

Yes!

Just hitting the ball can be hazardous,

but if it's in a bunker,
things get even more complicated.

So let's get out the driver
and tee up some science to explain why.

Playing the ball out of a bunker,

our golfer uses a special golf club
called a sand wedge.

He has to aim to hit the ground
a couple of inches before the ball.

Get it wrong, and he could end up
with a mouthful of sand.

[coughing]

When the golf club hits the ball,

it applies a force
that's perpendicular to its face.

With a relatively steep launch angle,

the ball follows
a high parabolic trajectory

with a short range
to get up and out of the bunker.

[cheers and applause]

Hitting the sand
helps to shift a stuck ball,

but a good swing is still needed

to transfer kinetic energy
to a partially buried ball.

The theory is simple,

but let's see how easily
it can be applied on the golf course.

Remember to keep your focus.

And hold of your club.

You're gonna need that again in a minute.

[man] I don't think
you're going to make it.

[Dallas] Well, that's not gonna
help his confidence, is it?

[dramatic chords]

-[glass shatters]
-[Dallas] But you were correct.

The limited cohesion between sand grains

means that sufficient energy
from his swing

should be transferred to the ball.

But he struck too far behind,
so he needed to shift too much sand,

wasting the energy from his swing,

making him lose his footing,
his club, and his dignity.

[glass shatters]

Ah, this looks better.

Actually, is that even sand?

-Aah!
-[man] Oh!

[Dallas] It all seems a bit academic now.

Maybe this guy's been paying attention.

-Ah!
-That'll be a no.

An inaccurate swing
made his trajectory too shallow,

and at the point of contact,

kinetic energy is transferred
from the club to the ball,

which bounces off the bank

and painfully into his shoulder.

Well, at least he can laugh about it.

As can we.

[bell rings]

[objects clattering]

OK. Right, class, pay attention.

Put it away, James. Thank you.

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

that part of the show
where we place a scientific principle

into our petri dish
and then see what cultivates.

So who can tell me
what the following are demonstrating?

This dangerous dancer...

Aah!

This diving dimwit...

and this elasticated endeavor.

-Aah!
-That's a strange hobby.

That's right. They're all examples
of the effects of resultant forces.

Now we know that a force
is a push or a pull on an object,

but what happens
when there are multiple forces

interacting with each other?

As this cheerleader is thrown in the air,
the upward force from their arms

briefly exceeds the downwards force
of gravity,

creating a resultant
force directed upwards.

Once in the air,
only gravity is acting on her,

and although her movement
is still upwards, she decelerating

until gravity overcomes her momentum
and she starts coming back down.

When she's caught, the catchers' arms
again exert an upwards resultant force

for a controlled deceleration.

Well, I hope that all makes sense,
because it's time for your test.

Question one.

What happens when one force is bigger
than the others acting on an object?

Ah, the garden trampoline.
Perfect for spying on your neighbors.

-Ooh!
-Less perfect for your health.

The rebounding elastic of the trampoline

produces a force
that's larger than his weight,

so there's a resultant force upwards
that launches him into the air.

But when that force isn't directed
straight up, he won't be either.

-Ooh!
-[laughing]

Question two.

What forces are acting on you in freefall?

-[light music]
-Ah, it's always good

to get your Christmas tree
well in advance,

and this is a novel way
of finding the best one.

Too short, too bushy, too tall...

and...we have a winner.

When falling with a parachute,

the downwards pull of gravity

is soon equalized
by the upwards force on the canopy.

There is no resultant force at all,

and he's gliding at a constant
and relatively slow speed

until the tree exerts
a somewhat larger force to stop it.

There'll be no Christmas this year.

Now, last but not least,
question number three.

Is the resultant force always
in the direction of the largest force?

Our trusty testers are experimenting
with a specially prepared bottle of cola.

[woman] Throw it this way!

[Dallas] Don't worry,
they've done a risk assessment,

so I'm sure nothing bad will happen.

-Aah!
-[Dallas] Apart from that.

The angled launch of the bottle

gave it vertical
and horizontal propulsive force,

and while gravity counteracted
the vertical acceleration,

the horizontal acceleration remained.

[woman] Aah! Oh, my God!

[Dallas] Which I'm sure our camerawoman
is very pleased about.

So that is the end of our lesson
on resultant forces.

Look at me!

I'm so [bleep] cool!

[screaming]

[all] Oh!

[Dallas] That was both stupid
and incredibly dangerous.

But luckily, a bit of science saved him
when his parachute opened.

He did have a parachute, didn't he?

Class dismissed!

[electricity crackling]

When I was at school,
I was desperate to win

the teachers versus pupils
tug of w*r competition.

Unfortunately, we never won,

because they were fully grown adults
and we were seven years old.

Maybe if we'd thought
about the science a bit more

we'd have stood a better chance.

Like this guy.
He's found the perfect way to practice.

I'm not sure
what his friend's doing, though.

What's important is lots of training.

And they're not gonna win anything.

And remember...

use a rope, not a tree.

Getting to grips
with your pulling technique

is not as easy as you might assume.

Ignore the science, and you might end up
looking rather stupid.

During a tug of w*r, the two teams exert
opposing pulling forces on the rope

to take up the slack.

When taut, the high tensile strength
of the thick rope

is able to withstand the tensile stress
they're applying.

The force on the rope combined with
the reaction force at their feet

creates a turning effect
that tries to rotate them forward.

So to counter this they lean backwards,

creating an opposite turning effect
using the force of their weight.

Turning to the side
helps to achieve a deeper lean.

An angle of less than


Pull hard enough, and the rope could snap.

You really don't want that,

because flailing ropes
can do permanent damage.

So ensure yours has some elasticity.

So there you have the science,

but what happens
when it's put into practice

in a less controlled environment?

What better way to resolve a long and
painful family dispute than a tug of w*r?

[all scream]

Hopefully, that settled
all their differences.

During the tug of w*r, the teams exert
pulling forces in opposite directions.

The more competitors on each end,

the greater the tensile stress,

which eventually overcomes
the tensile strength of the rope...

causing it to snap.

Let's call that one a draw.

Now, tractor tug of wars are very,
very dangerous and extremely silly.

[crowd yelling]

But don't worry.

Our fearless farmer scrambled free
from this one-sided contest.

[all shouting]

To be a great anchorman
requires a solid build,

strong physique,
and, as this guy demonstrates...

a natural gift for comedy.

[laughter]

With a large enough lean,
he can generate a ground reaction force

that has a significant
horizontal component.

But without it, the pulling force
combines with the friction at his feet

to create a turning effect

and throws our anchorman
down into the dirt.

[laughter]

These days, there are so many
ways to communicate,

we just take it for granted.

But we should never underestimate
how important it is to express yourself.

[singing]

Like this soulful songstress...

[jazzy piano]

-[meow]
-And her critical cat.

-Blblblblb...
-Or this dad

with his baby girl.

And a look that says it all.

Blblblblblbbb...

Our world is full of
weird and wonderful creatures

that communicate
in a myriad of different ways.

But what is the science
that makes it all possible?

[bright music]

Animals communicate in a number of ways

including using sight and sound...

-[clicking]
-to convey a wide variety of information.

Visual communication can range
from very simple to complex

but relies on a clear line of sight.

Auditory communication
ranges from simple grunts...

[long grunt]

To the intricate language of humans.

And unlike light,

sound is not easily stopped
by obstructions in the environment,

so animals don't need to see each other
to communicate in this way.

And the sophistication of visual
and auditory communication

tends to increase with the complexity
of an animal's social structure.

If you're ever feeling husky,

it's always worth
trying to clear your throat.

-[bagpipes playing]
-[dogs howling]

Hector here is demonstrating
his pack howling instincts

and soon has this pair
of spaniels singing along.

Although I'm not quite sure
what that song might be.

-[bagpipes continues]
-Catchy, though.

Gorillas beat their chest
to communicate their dominance,

and this baby is trying to prove
that he's big and tough.

Looks like he doesn't
know his own strength.

We all know that horses are useful

for getting rid of
any spare apples you have,

but they can also offer style advice.

So what do you think about my outfit?

[horse grunting]

It's hard to look cool while
your friend looks ridiculous.

Hashtag: embarrassing!

This c*ck's dance
is instinctive behavior

and illustrates
his elaborate courting technique.

Such a display shows
that the bird is in good health

and in this case it may also be
a good indicator of why he's still single.

[electricity crackling]

Well, that brings us to the end

of yet another eye-watering,
toe-curling, leg-crossing montage

of science and stupidity.

And here's a final reminder

of why you shouldn't
try any of this at home.

[lively banjo music]

[men groaning]

Aah!

[man] Oh, no!

[all] Oh!

Ahh!

[woman] Ahh! Oh, my God!