03x02 - BASE Jumping, BMX and Sword Skills

[bunniefuu]

-[Richard] This...
-[glass shatters]

is The Science of Stupid.

[electricity zapping]

Yes, this is the show that combines
science with stupidity.

Settle in for half an hour
of moronic excess.

As everyday people who really
should know better,

risk life and limb for little
more than cheap thrills.

We'll reveal what went wrong... and why.

By exploring such scientific marvels...
as tensile strength,

impact force,

and Newton's Third Law of Motion.

Ignore them at your own risk.

It's The Science of Stupid.

[glass shatters]

[electricity crackling]

In this show we'll explore momentum,

the swing of a pendulum... striking

and the exploitation
of gyroscopic stability.

But first, this.

[glass shatters]

[electricity crackling]

My introduction to cliff diving
was on holiday in Greece.

I was 14.

There were local girls watching,
and I was keen to impress them.

I like to think it looked like this...

Actually it looked and felt...

like that.

Yep, cliff diving
is exceptionally dangerous.

You might hit the rocky side,
hit a rock beneath the water

or hit the water incorrectly.

Which actually feels like hitting a rock.

My advice, don't do it.

But for the sake of scientific knowledge,

here's how those who do do it,
do it right.

He needs sufficient friction
at the push-off point

for a large
reaction force from the ground.

This gives him enough forward velocity

to clear the cliff face
and any rocky outcrops.

The correct amount of angular velocity
rotates the body

so it points in the right direction.

Thereby minimizing hydrodynamic drag
when it enters the water...

[cheering and groaning]

Ideally.

Be warned. Diving off a cliff can result
in spinal and neck fractures.

And that's just from the impact
of hitting the water badly.

Now according to the science,
we start with friction at the top.

This is the crucial first step
from which everything else follows.

[girl, off-screen]
You're crazy.

[Richard] Maybe.

[screams]

Or maybe he's just a bit slippery.

A dry, flat launch might be better.

[groans]

[boy, off-screen] Oh ****!

[inaudible]

[Richard] But if you miss the launch...

you get no friction at all.

A sure footing is important,

because it helps in getting
enough forward velocity

to clear the cliff face on the way down.

[boy screams, groans]

That was close.

Shame about the feet.

[man, off-screen]
One, two, three, and [bleep].

[groaning]

[Richard] That was a bit closer.

[man, off-screen] Is he okay?

[Richard] He's fine.

That forehead needed a shave anyway.

And then, there's this.

[woman, off-screen]
Don't do it, you idiot!

[Richard] Well that's a bit personal.

[screaming]

Oh, maybe she was right.

If it's friction you're after,
sliding down the cliff

rather than jumping down
next to it, will do it.

[screaming]

But it is going to sting in the morning.

Next, angular velocity.

[man] Oh, yi-yi-yi-ohh...

[Richard] Oops, not enough there.

[woman] I'm not afraid to do it now.

[man, off-screen] Just flip more.

[Richard] Good advice.

[man, off-screen] Oh!

[Richard]
I think he meant more than that.

[man, off-screen]
Oh my God, did that hurt?

[Richard] Probably. And here's why.

Remember hydrodynamic drag?

It's the reason you're better off landing
in a pointy way,

because the larger and flatter
the surface, the bigger the drag.

You see, the water molecules
can't move out of the way fast enough.

[woman, off screen] Oh, my God.

[man, off-screen] Ooh...

[Richard] A bit like that.

It's called a belly flop.

And to make matters worse,
for every second you fall,

your speed increases by 22 miles an hour.

Before air resistance takes over.

If he'd hit those rocks...

that would've been even worse.

[screams]

Now, that was about
two seconds of falling.

So he hits the water
with the same momentum...

[screams]

as a 42-pound cannonball
traveling at 200 miles an hour.

[screams]

Now that is fast.

[electricity crackling]

When I was a kid,
hammers were simply things

that cats used to hit mice
with in cartoons.

As a man, I learned hammers
have very practical uses.

Still about hitting things though.

Hammers are brilliant
if you have a problem with walls...

[screams]

And ceilings...

[bleep]

[glass shatters]

Or if you can't find your remote control.

Or if you just hate yourself.

He's going to be so cross
when somebody shows him a workbench.

The science of hammers
is essentially about

swinging a large mass
on the end of a handle

fast enough to get
a decent amount of force.

Here's how it works.

Swung around a pivot point at the elbow,

the hammer gains momentum
exerting a large impact force

when it hits the nail.

The nail's sharp point applies
high local pressure on the wood.

Increasing the hammerhead's weight
and its distance from the pivot point,

results in more momentum...

and more force.

So in a nutshell, the longer the handle
and the heavier the head,

the more force you can get.

Of course, you don't always
need that much.

So you want different hammers
for different jobs.

Although this looks more like
some sort of medieval weapon...

and it's not really working.

Oh, that's better. Now he's using
the pressure technique.

Small hammer and chisel,
all the force focused in a tiny area.

Still not working.

Key maybe? I don't know.

This rubber mallet is probably heavier.

[woman, off-screen] The other way.

[Richard] But also bouncier.

Should've listened to your mum.

[boy] Good call.

[Richard] Yeah.

Now, if you double the mass
of the hammer head

and double the length of the handle,

you get four times the momentum.

But just bear in mind there can
be a bit of momentum

on the other end too.

-[boy] Ooh.
-[Richard] See?

[man] You alright?

[Richard] Probably not.

But how can you get
even more momentum on your hammer?

[boy] Ooh.

[Richard] Oh yeah, hang it on a rope.

[man]
Alright, I have a surprise for Cody.

[Richard] Damn brilliant. I love
surprises!

[woman]
It's gonna suck.

Can't wait.

[groans]

[Richard] Oh.

[Cody] I think you
just broke my kneecap.

[Richard] Yeah, he probably hasn't.

But by increasing the distance
from the pivot,

he has increased it's momentum.

And probably the impact force.

[man, off-screen]
I'm pretty sure you're gonna be okay.

[Richard] I'm not. Don't try this at home.

[electricity crackling]

Can you guess which scientific principle
this goalkeeper is about to demonstrate?

[glass shattering]

[electricity crackling]

[Richard] So what science
is this goalie about to show us?

[screams]

Well, absolutely nothing,

but his little brother has just
demonstrated the transfer of momentum.

Some of the ball's
momentum transfers to the boy,

and he transfers into the shed.

There, there, it's only science.

[electricity crackling]

If there was ever a machine
that symbolized complete freedom,

it's the motorbike.

But if you can't afford that,
it's the moped.

So simple. All you have to do
is pop your helmet on,

twist that throttle and go.

[groans]

Oh, and do look out for your friends.

He was your friend.

Oh, and watch out for... curbs.

And of course...

other motorists.

In fact, there's more to staying
on a moped than people think.

Here's a little primer,
courtesy of our old friend, science.

For front-to-back stability,
the combined center of mass

must stay above the base of support.

But a moped's small wheels
are close together, decreasing stability.

Side to side, the narrow base
must move to account

for a shifting center of mass.

Gyroscopic effect provide some stability.

But the slower the wheels turn,
the less stability you get.

Fair to say then that the moped
isn't the most stable of vehicles.

But if those little wheels
are spinning fast enough,

the gyroscopic effect might help.

Right, armed with these basics
let's start by going in a straight line.

[man, off-screen] Push the gas...

Push it. Push it.

[Richard] That was straight,
but in the wrong direction.

Sending her into the trailer
and knocking her little base of support

out from under her center of mass.

Oh, a little wheelie, but don't worry,

the center of mass is over
the base of support...just about.

Now, relax the throttle...

and back into the safe zone.

[man] Oh, whoa...

[Richard] See? Safely parked.

[man] Oh, whoa...

[Richard] Next, stopping.

And can this little lady
keep that bike stable?

Oh, no, she can't.

The gyroscopic stability
tailed off as the wheels slowed...

and her legs, uh...well, they're too short
and too weak to prevent a topple.

Yeah, you're grounded.

Riding in a straight line is one thing.

But when it comes to
leaning left or right,

there is a point where
the gyroscopic stability is overcome.

And the bike becomes wobbly.

Can you guess where it is?

Yeah, it's-- it's about there.

Lean too far on a turn, and no amount
of gyroscopic effect is going to help.

Has he got it?

[groans]

Clearly not.

Well, at least he's using his indicators.

Going down, apparently.

This girl's got it.

[woman, off-screen] Oh no.

Carly!

[Richard] Oh. So gyroscopic stability,

center of mass over base and...

don't forget those parked cars.

[bubbling]

[glass shattering]

Now for today's science lesson.

Apparently there's too much silliness
in this show,

so this is the bit where we focus
on a particular scientific phenomenon.

See if you can guess what it is
from the following clues.

He's in one...

[man] Oh, h*, h*.

[Richard] Kind of.

And he's on one...

[screams]

[laughter]

Well, he was...briefly.

[boy, off-screen] Are you alright, dude?

Just run it off.

[Richard] I'm not sure that'll help.

What these people have in common,
apart from a total disregard for physics,

is that they are all part of a pendulum.

And here's how it works.

A pendulum is a mass swinging
from a fixed point.

Gravitational potential energy changes
into kinetic energy and back again.

Gravity and momentum
keep the object moving,

and centripetal force from tension
in the rope swings it around the pivot.

At the bottom of the swing,
the tension in the rope is greatest.

For maximum horizontal distance,

the point to leave the pendulum
is usually less than 45 degrees.

Right. A little test.

Question one. Where is the tension
at its greatest?

[screaming]

That's right, at the bottom of the swing.

So where's the tension greatest here?

[laughter]

Probably the frame.

Once past the vertical,

gravitational potential energy
builds up again,

and the tension decreases.

So question two.

Where is the point to let go
for maximum distance?

It's less than 45 degrees.

Around there.

[screams]

Uh...

Bowling follows a similar principle.

And in this case, he'd have been
better off closer to zero degrees.

Will he let go in time?

[man, off-screen] Go.

[groaning]

[Richard] Oh, a bit late.
Stroke not at all.

Pushing out to the side creates
a three-dimensional pendulum,

which is harder for him to predict.

[groaning]

Clearly, he didn't see that coming.

Right, question three
of our science lesson.

At the top of a swing,
what forces are acting on the mass?

A little tension...

[groaning]

and a lot of gravity.

[laughter]

Fortunately, the smaller the mass,
the smaller the force of its weight.

[screams]

Relatively speaking.

So pendulums, complicated in theory,
unpredictable in practice.

[screams]

MAN [off screen] Oh! Oh dear.

[glass shattering]

[electricity crackling]

[Richard]
Gyms are great, aren't they?

Grunting and shouting "yeah"
at other semi-naked people.

I love it. But getting fit
is a long process with lots of steps,

and some of those steps are on ladders.

Not this kind of ladder.

Too easy...

[laughter]

for most of us, most of the time.

I'm talking about this.

The salmon ladder.

It takes skill, strength and, uh...
coordination.

[man] Fail!

[Richard]
You said it.

Leaping like a salmon
from one rung to the next

is no mean feat.

But as always,
science is here to help.

The athlete must exert enough force
to overcome gravity and his inertia.

Lifting his center of mass whilst
keeping it close in line with his bar.

This generates the momentum

to provide enough flight time
for reaching the next rung.

If he tires, it gets harder
to exert enough force.

His momentum slows...
and gravity does its worst.

Heaving yourself up to one rung
on the ladder

is the equivalent of six normal pull-ups.

so the key is getting enough momentum
from the start.

Not that much.

That'll do.

Plenty of momentum will help
get that bar over those hooks.

But you do have to keep it up.

Yeah.

Okay, maybe one last try.

Or maybe not.

Right. Force, momentum, center
of mass and endurance.

To succeed, you need to nail all four.

[man, off-screen] Last one.

Oh no!

[Richard] Oh yeah.

[man, off-screen]
Three out of four is pretty good.

[Richard] No, not really
good enough though, is it?

So, what about this guy?

Oh... not even one.

[screaming]

But once you're confident, you can start
adding extra manly flourishes.

[man, off-screen]
This is muscle up salmon ladder.

[Richard] Yeah, look at that.

If you do this, friends will gather around
to encourage you...

[groaning]

And laugh when you fail.

[electricity crackling]

If, like me, you're a fan of both
yoga and acrobatics,

then you'll be thrilled
to discover that there is now

an activity that mixes the two.

It's called acro-yoga.

Two people balancing on top of each other,

moving fairly
slowly in a variety of poses.

There's the firefly on hands.

It's a classic.

The super yogi...ooh, tricky.

And... whatever this is.

[gasps]

Rubbish. It's the rubbish.

Perfecting this otherwise tedious activity

frequently involves falling on your head,
or tumbling onto your partner's groin.

To avoid that, and you should,
you're going to need some science.

The lifter must generate just
enough angular momentum

to rotate their partner into position.

A piked position, body bent,
legs straight,

moves the liftee's
center of mass downwards,

over the base of support
at the lifter's feet, for stability.

But if that center of mass
moves outside the base,

he will pivot to the ground.

Which means fall.

So that was the front bird
into folded leaf pose,

as if it needed saying.

But that same science is fundamental

to all your favorite acro-yoga techniques.

Let's start by getting into that perfectly
balanced piked position.

Doing that relies on plenty
of angular momentum.

But not that much.

Too much.

Less of a professional look here.

Still, nice controlled angular momentum
into position.

Center of mass over base of support.

There's even a couple of new poses
we haven't seen yet.

[screams]

And that's another one.

[man, off-screen] Did you sit on her face?

[Richard] She did.

[screams]

But that's not an official position.

Right, what have we learned?

[glass shatters]

Okay, not a lot.

Standing up took their combined

center of mass further outside the base...

[glass shatters]

and then significantly closer
to the side table.

Okay let's-- let's just face it,

when done properly,
acro-yoga is a bit dull.

[screams]

Oh, but it does have its moments.

[glass shattering]

[electricity crackling]

And that's all the science-related agony
we have time for.

Please do not attempt
any of the stunts you've just seen.

We'd hate to lose you
and hope to see you again

for The Science of Stupid.

[screams]

[screams]

[screams]

[groaning]