08x16 - Predators, Helicopters and Flammability

[bunniefuu]

DALLAS [off-screen]: This
is the Science of Stupid.

DALLAS [off-screen]:
Yes, this is the show that gathers up the science

from a pile of stupid.

Sit back as enthused
researchers take on the universal laws

so you don't have to.

We'll reveal what went wrong
and why with the help of scientific principles

such as elastic
restoring force, momentum,

and that sneaky
critter hydrodynamic drag.

So, observe but never imitate.

Watch out,
it's the Science of Stupid.

DALLAS [off-screen]: In
this episode, we'll be studying

the parabolic trajectory
of a dry ski slope jumper.

[screams].

DALLAS [off-screen]:
We'll be turning up the heat with flammability

and exploring the power
of buoyancy,

but first, this.

DALLAS: Renaissance artist
and all-round smart cookie, Leonardo Da Vinci,

famously painted the Mona Lisa
and the last supper but he also

may have been the first person
to design one of these.

DALLAS [off-screen]:
Nope, not the wakeboard, that thing in the sky,

also known as a helicopter,

and it's not only wakeboarders

that helicopter pilots
are helping out.

The best can use their skills

to save calves
from frozen lakes.

MAN: There you go!

DALLAS [off-screen]: Da Vinci
was ahead of his time, although there were less

cow rescues in his
pictures, from memory.

DALLAS: But before a pilot can
head off for a little cow skimming they need to know

their heli science.

DALLAS [off-screen]: A
helicopter generates lift

from its rotating blades,

adjusting the collective pitch

changes the angle
of all blades simultaneously,

allowing the helicopter
to increase

or decrease in altitude.

Adjusting the cyclic pitch
will change the angle

of each blade at specific
parts of its rotation,

creating more lift on one side
leading to forwards,

backwards and
side-to-side motion.

Changing the pitch
of the tail rotor blades

rotates the helicopter left
or right like a rudder.

DALLAS: Thus you need
to master a combination

of cyclic pitch,
collective pitch,

and tail rotor pitch
for successful flight.

Okay, let's take it
one step at a time.

MAN: I'm spinning up.

DALLAS [off-screen]:
First, we need to take off,

which is easier said than done
in a homemade car copter.

Well, this
doesn't look dangerous.

Please fasten your seatbelts

as we may be experiencing
some turbulence.

MAN: Keep it going,
keep it going, keep it going!

DALLAS [off-screen]: And
a touch of impact force.

The faster he's pulled,

the quicker the blade's
auto rotate,

which eventually creates
enough lift to raise him

but as the car copter rotates
to the side that lift force

makes it travel sideways
faster than his rudder can correct.

Luckily the pilot was fine,
which is more than can be said for the Reliance Robin.

Maybe best to stick to
a proper chopper with an actual tail rotor.

This research pilot is using
a combination of collective pitch to descend

and cyclic pitch
to move forwards.

Now for the perfect landing.

Ah, that wasn't
important, was it?

A sudden dip in collective
pitch caused his blades to intersect with a power line so

it shorted but I don't
think anyone noticed.

Yeah, that might be
a bit of a giveaway.

Yes, like take-off coming
in for landing can be the trickiest skill.

Nailed that one though.

[screams].

DALLAS [off-screen]: The pilot
adjusts the cyclic pitch to create more lift on the

right-hand side, drifting the
helicopter to the left but the building has possibly affected

the airflow and his
aerodynamics, so the pilot decides to teach it a lesson.

[screams].

DALLAS [off-screen]: I mean,
I could see it coming but then again I am cyclic.

DALLAS: Okay, this is the
part of the show where we like to take a break from

the stupid and concentrate
on someone who actually knows what they're doing

and what they're doing
is breath-taking.

DALLAS [off-screen]:
Meet Tom Morgan, thrill seeker extraordinaire.

Tom and his team have spent
the last two days filling 100 large multi-colored balloons

with 162 cubic meters
of helium.

He wants to use the balloons

to fly across the plains
of Africa

suspended in a garden chair.

Colorful but crazy.

NICK [over radio]:
Have a good flight Tom!

TOM: Thanks, Nick.

DALLAS [off-screen]: Lighter
than air the helium gas

drifts him high
over the plains of Africa,

which is probably best

to avoid lions
eating his loafers.

Looks like they've got
hold of his jeans though.

After nearly 16 miles and at
heights reaching 8,000 feet,

Tom finishes his trip
and lands safely.

TOM: That was so...

so cool man!

DALLAS: Incredible.

Of course, Tom was supported by
a whole backup team and safety was their first concern,

so don't try this at
home or anywhere else because for every Tom...

DALLAS [off-screen]:
There's a Richard.

[screams].

DALLAS: Tom could pull off
this amazing stunt because he understood

the scientific principles
of what makes balloons rise.

DALLAS [off-screen]:
Helium and hydrogen are less dense than air,

so a balloon filled with one
of these will be buoyant in the surrounding air

but should the buoyant force
become less than the weight of the balloon,

and man, they'll sink.

Alternatively you can use warm
air because heat will cause the air to expand,

reducing its density compared
to the surrounding air producing a buoyant force.

This upward buoyant force
needs to be greater than the weight of the balloon

and its payload for it to rise.

DALLAS: And of course
the large surface area of balloons means they

experience a lot of drag.

The question is were our
other aspiring balloonists paying attention?

DALLAS [off-screen]:
Probably not.

The large amount of drag the
balloons are experiencing due to their large surface area is

enough to overcome their
attachment to the car.

Fun for other commuters,
appalling for the environment and sad for the six-year-old

who's now hosting a
balloonless birthday party.

In a relationship nothing says
love more than releasing helium-filled heart balloons

out into the world
but releasing them into

a power line suggests the
relationship is doomed.

The helium-filled balloons had
enough buoyancy to overcome their weight but they couldn't

rise quickly enough to
avoid the power lines.

That's shocking and
once again shockingly bad for the environment.

DALLAS: Now, I don't want to
be a party pooper but we are actually running out of

helium, which is ironic as
it's one of the most common gases in the universe,

just not here on Earth.

So, what if we used hydrogen?

DALLAS [off-screen]:
That's lighter than air but also very flammable,

so maybe we should
just use hot air.

Heating the air generates
a buoyant force that enables the balloon

to rise fairly quickly.

DALLAS [off-screen]:
Just not quickly enough.

[screams].

DALLAS [off-screen]: Wow, this
drone is capturing some epic footage but can you guess the

scientific principle
we're about to see?

DALLAS [off-screen]: Did
you guess the science this drone footage would lead to?

Yes, that's right.
It's reaction time.

The pilot accelerates the
drone to chase the car but gets the angle wrong,

so heads straight towards it.

By the time they notice the
mistake they only have about a quarter of a second before

impact, which is about the
same as the average human reaction time but just too

brief for them to
save the drone.

DALLAS: I love ski jumping,
so much so I just can't wait for the season.

Thankfully a Science of Stupid
researcher tells me he's been hard at work on a solution.

MAN: Oh, oh.

DALLAS [off-screen]:
Not hard enough though.

DALLAS: Even launching off
properly constructed dry ski jumps can be fraught with all

sorts of tricky physics.

For instance...

DALLAS [off-screen]: A dry ski
jump will generally have more

static friction than its snow
counterpart and this will need to be overcome to get moving.

To gain speed for a jump the
skier will use gravity to accelerate and the lower the

friction the less
resistance they'll encounter.

When jumping their parabolic
trajectory is set by the launch angle and the launch

velocity, and, as with normal
ski jumping, you need to keep your base of support below

your center of mass for
landing to prevent accidents.

DALLAS: So, it's similar to
traditional ski jumping only with more friction and the

landings can be a lot harder.

To avoid the painful side of
that we start by gaining just enough velocity.

DALLAS [off-screen]:
That was not enough.

He didn't have sufficient
take-off velocity to give him a long enough parabolic

trajectory, so he ends up
under rotating, which means his center of mass was in

front of his base of support.

At least he didn't get a face
full of snow, just a tough, abrasive carpet.

A steeper slope
should help with velocity.

[screams].

DALLAS [off-screen]: Unless
you use your head as a brake.

He had decent velocity this
time but throwing his weight back too soon meant the

resulting rotation
brought his head into play and not fun play.

More like concussion play.

Maybe try it without
the flip next time

but not
without the jump.

He gathers speed thanks to
gravity and low friction but he leans too far back.

Popping one of his skis off,
which increases his friction,

and slows his take-off velocity.

Grabbing at the edge gives him
that last bit of friction he needs to avoid landing in that

giant bowl of spaghetti.

Textbook.

DALLAS: Over millions of years
predators have evolved to become k*lling machines,

fine-tuning their skills to
maximize their k*ll rate.

DALLAS [off-screen]: Rising
to the top of the food chain.

Others...

[laughter].

DALLAS [off-screen]: Well,
they're still working at it.

DALLAS: Strategies used by
predators for a successful hunt include chasing,

stalking and ambushing,
and sometimes a mixture of all of them.

DALLAS [off-screen]: Chasing
takes both time and efforts to make a successful k*ll,

so chase predators concentrate
on prey that will provide enough nutrition.

Stalking uses much less
energy and relies on stealth and patience.

Cats, for instance, have
evolved soft padded paws and retractable claws that help

them walk silently and for
ambush attacks predators rely on not being seen through

concealment or camouflage.

DALLAS: Whatever the
animal's specialty there is one common factor,

catching prey is a lot
harder than it looks.

DALLAS [off-screen]:
This lion is using the classic chase method,

direct and deadly.

Unfortunately the wildebeest
is also using the same technique in defense.

If the wildebeest had been
more accommodating it might have made a nutritious,

protein-rich meal but
if risk outweighs reward it's just not worth it.

Like this dog chasing a
squirrel and missing it.

Chasing can waste a lot of
energy, especially when you're dragging around a heavy human.

Oh, maybe it was worth it.

Stalking is a lot
more energy efficient,

these hunters
target and silently creep up

on their unsuspecting prey.

I said unsuspecting.

Stalking comes naturally
to some predators, others need a few parental lessons.

Then there's the ambush,
concealed or camouflaged the hunter can wait all day for

the perfect moment to strike.

DALLAS [off-screen]:
Or they can go early and miss completely.

This cat clearly has
work to do on its distance estimation but its doggy

paddle is coming along a treat.

DALLAS: Scientists believe
it was our ancient ancestor, h*m* erectus,

that first harnessed the power
of fire and it's a knowledge we've taken through the ages,

all the way up to...

DALLAS [off-screen]:
h*m* clownius.

Thankfully she was fine but
it's a good warning of how dangerous playing with fire

can be, as if clowns
needed to be any scarier.

DALLAS: The ease with which
a substance catches fire is called its flammability and

two key factors that
determine it are oxygen supply and surface area.

DALLAS [off-screen]: A
material with a small surface area relative to its mass will

not easily ignite as it needs
time to heat sufficiently to sustain combustion.

If the same material has
a greater relative surface area the small particles

are quickly heated releasing
a large amount of volatile gases that react

with the oxygen in the air.

Materials like wood need
oxygen to combust but some things like sparklers can burn

without air as they bring
their own supply of oxygen in the form of an oxidizer.

DALLAS: So, now we
know the science...

DALLAS [off-screen]: We know
what would be a really bad thing to do right now.

Yup, flow paper confetti
around and there's your proof.

The sparkler fountains burn
readily as they contain an oxidizer and the paper

confetti has a large surface
area relative to its mass so quickly combusts.

Not a good combo.

Still, at least now
everyone is dancing.

Worried your sparklers
might set off your smoke alarm, well,

why not extinguish them?

That's one dealt with.

Now, how about the rest?

[screams].

DALLAS [off-screen]:
Oh, that is poor science.

The sparkler's oxidizer means
they continue to burn even when their air supply is

restricted by the towel.

MAN: Whose towel is that?

DALLAS [off-screen]: Yeah,
I'd probably worry more about whose floor it is.

WOMAN: It's my towel!

DALLAS [off-screen]: Err,
I, I've changed my mind.

Worry about the towel.

Aww, who's birthday is it?

WOMEN: Dear Britney...

DALLAS [off-screen]: Aww.

Happy birthday, Britney, and
what better way to celebrate than with good friends,

delicious cake and...

DALLAS
[off-screen]: Fire, fire.

Strands of hair have a large
surface area relative to their mass and so can easily set

alight, luckily her friend's
on hand to blow it out.

DALLAS [off-screen]: Go on,
make a wish for new hair extensions maybe.

DALLAS: Some people think
that taking the trash out is just a boring chore,

and they're completely right.

DALLAS [off-screen]: Aside
from being tedious it can also be a messy business.

DALLAS: To avoid embarrassing
spillages in front of the neighbors you need to face

up to the science of
the trash throw.

DALLAS [off-screen]: To land
it in the can the thrower needs to give the bag the

right launch
velocity and angle.

It then follows a parabolic
trajectory under the influence of gravity.

Swinging the bag in
preparation for the throw means the trash experiences

a centrifugal force.

If this overcomes the tensile
strength of the bag it will rip and the contents will

initially travel in a
straight line as a result of their inertia.

DALLAS: But getting the
trash into the can doesn't have to be a grind.

Our researchers have been
livening up the art of the trash throw.

DALLAS [off-screen]: He's
pretending to be a flying helicopter but he's actually

more of a flying
trash dispenser.

As he swings the bag around,

the contents experiences
a centrifugal force

pushing outwards,
and thanks to inertia,

when he lets go, they continue
straight into the road

causing the weak plastic
to tear, releasing the trash.

And instead of doing the
right thing and picking up his mess...

MAN: Just run!

DALLAS [off-screen]:
He just does that.

These workers are spicing up
their work duties with a classic backwards blind throw.

DALLAS [off-screen]: Perfect
parabola and anything he can do his friend...

MAN: Oh.

DALLAS [off-screen]:
Can do messier.

Our first thrower gets the
launch velocity and angle spot on for the perfect trajectory

into the dumpster.

The second thrower swings
hard so the contents of the bag experience a large

centrifugal force overcoming the
tensile strength of the bag.

MAN: Oh.

DALLAS [off-screen]: As for
the camera man he just loves inertia in his face.

Taking the trash throw
to another level are these flat mates.

[laughter].

DALLAS [off-screen]:
It might be more fun but it's not very effective

and it could be dangerous.

He's very slightly overdone
the launch angle, unless he actually aiming for his

friend, in which
case it was perfect.

[laughter].

DALLAS: And that's it, that's
quite enough stupid for now.

As inventor Alexander Graham
Bell allegedly said, 'Before anything else preparation is

the key to success.' Well,
Alexander, look away now as our intrepid researchers

continue to do no
preparation whatsoever.

[music plays through credits].

♪ ♪