02x05 - Wall Running Face Plants

[bunniefuu]

[Richard, off-screen]
This is the Science of Stupid.

[Richard, off-screen] Oh, yes.

It's the show that fuses
science with stupidity.

Before sitting back and
observing the consequences.

We'll be enjoying
miscalculations

from some of science's most
misguided researchers.

[man] Ooh!

[Richard, off-screen] Before explaining
what went wrong and why,

by exploring scientific
principles like lift.

Friction.

Momentum.

And aerodynamics.

Science takes no prisoners.

Treat it with respect or
you will feel the pain.

Don't try this stuff yourself.

Take cover.

It's the Science of Stupid.

On this show we'll see what happens
when you fail to convert

kinetic energy from
horizontal to vertical.

-[man] Ooh.
-[laughs]

[Richard, off-screen]
Study the effects of drag.

Or lack thereof.

[man] I have a
bloody nose hardcore.

[Richard, off-screen] And highlight the
importance of friction.

But first, this.

Standby to be impressed.

Not a phrase you'll
hear often on this show.

If ever at all.

But get ready to see something
really, really cool.

[Richard, off-screen] Want to see
something slightly less cool?

In fact, extremely uncool and
carrying a very real threat

of breaking your neck.

So how can some
guys dive into the sea

from giant cliffs and emerge
unscathed whilst others end up

with bloodied noses when diving
from the bank of a river?

Well, the answer lies in
deceleration or specifically

how it's affected by drag.

That's the force on an object that
resists its motion through a fluid.

Not a man in a dress,
that's different.

[Richard, off-screen]
A streamline body

generates a small splash

and a low level of what's
known as form drag.

In layman's terms, it
travels faster for longer.

A blunt body creates a large
splash and lots of form drag by

presenting a large surface
area to the oncoming water.

Diving into shallow water
you need to slow down fast

so land as horizontally as
possible for maximum drag.

So what science
is telling us is you need

to adjust your diving method
to suit the depth of water,

especially when the
water is shallow.

Now where might we
find shallow water?

I know, at the beach.

[Richard, off-screen]
He's entered far too vertically.

And experiences minimal
drag but maximum pain

as he snorts wet sand.

Still doesn't
excuse the trunks.

Okay, let's
see if some stats help.

If you belly flop from three
feet form drag will stop you

in about two feet 4 inches.

Perform a perfect vertical
dive from the same height

and you'll travel around


What do those numbers mean?

When entering shallow water
move as much of it as quickly

as you can by making yourself
as big and blunt as possible.

[man] Okay, recording.

[Richard, off-screen] School's
out and time for summer fun.

Oh my god!

[Richard, off-screen] Or perhaps some
extra homework on the relationship

between drag and
deceleration in water.

And don't worry if you're not a
great diver but still want

to explore the effect of
splash and form drag in water.

[man] Ow [bleep].

[Richard, off-screen] It
works the same feet first.

Doesn't it boys?

[man] Ow [bleep]. [bleep].

[Richard, off-screen] Such
language for young pups.

The highest recorded dive into
a paddling pool containing


an incredible 37 feet.

Jumping off a chair
should be fine then.

Oh.

[man] Ow.
[laughs]

[Richard, off-screen] He was making all
the right shapes in mid air.

Offering up a large surface
area but that dip of the head

means he was actually pretty streamlined
at the point of entry.

And as we all know, nose
time's patio equals...

-[man] Ow!
-[Richard, off-screen] Well, that.

He's bleeding.

[man] I have a
bloody nose hardcore.

Get out of the pool.

I love motorbikes,

but I always follow
one golden rule;

don't stand up when you're
traveling at speed.

It's a bike not a surf board.

[Richard, off-screen] But not everyone
sees it the same as me.

Yes, I'm afraid
moto surfing is a real craze.

It's a thing.

Now motorbikes actually become
more stable as they pick up

speed from a walking pace.

Ideal speed is between


But here's a tip, the best way
to avoid injury when standing on

a moving motorcycle is not to
stand on a moving motorcycle.

Although if you really are hell bent on
destroying both your bike and yourself,

you might want to
listen to the science.

[Richard, off-screen] He
quickly gets up onto two feet,

keeping his center of mass over
the base between the wheels.

Positioning the feet as
far apart as possible,

widens his base of support
and improves stability.

To get back in the seat, he
jumps down with both feet

at once, because unbalanced
forces on one side would cause

the bike to wobble.

Ooh, backwards. He's got the confidence,
but has he got the speed?

No.

With the bike unstable
he was always going down.

Maybe it'll be easier
riding pillion.

Maybe it won't.

Ah, this looks better.

Good speed.

We might be getting somewhere.

Oh yes.

Oh, why do I say these things?

-[man] Oh [bleep] dude.
-[Richard, off-screen] Sorry.

[cameraman] Oh [bleep].

[Richard, off-screen] Remember,
center of mass above base.

No, no, not like that.

Shall we move on to
sitting back down again?

Now, do you
remember what I was saying

about bikes becoming more
stable at speed?

It's a handy thing when
you're standing up.

But when it's time to get
down it's worth remembering

that a motorbike continues self
stabilizing even if you're not on it.

Don't believe me?

A wide bike can offer
room for a wider base.

But by standing on one leg, he
narrows his base of support.

Both rider and bike wobble.

But at that speed, the
bike can right itself.

He can't.

Don't worry though, there is another
force that can stop a bike.

Physicists call it a wall.

This guy's launched his
own physics road show.

And here he is in hospital
a few hours later.

He's actually got off lightly.

Don't worry, that's his
hairstyle not an injury.

Don't try this yourself.

It is frankly stupid.

[cameraman] Alright Kirk,
it's all you man, yeah.

[Richard, off-screen] Uh-huh. Here's a
little question for you.

What force does our g*n
wielding sh**ter not take into

consideration when he pulls
the trigger of this revolver?

-[g*nsh*t]
-[man] Ahh!

[Richard, off-screen] Our first time
sh**ter falls foul of Newton's third

law; that every action has an
equal and opposite reaction.

The revolver is way too
powerful to fire with one hand.

Our sharp sh**ter doesn't have
the strength to withstand

the recoil and ends up with
a face full of metal.

But Sir Isaac's certainly not
responsible for that girly run.

Drag racing is the automotive equivalent
of the 100 meter sprint.

Two ludicrously powered cars
racing in a straight line

over a quarter of a mile in the
ultimate battle of pure speed.

I stress that these cars are
going in a straight line.

I do have history here.

[Richard, off-screen] Which begs
the question

why do so many of them end up
like this?

And this.

Well, it's because they
have a tendency to do this.

And this.

But why?

Let's start
with that tendency to wheelie.

It's caused by a moment.

I don't mean as in ooh
I'm having a moment.

I mean the turning
effect of a force.

Have you ever noticed how
it's easier to undo a bolt

with a long handled spanner
than a short handled spanner?

That's because the
distance between the nut

and where the force
is applied is greater.

So the turning effect
or moment is greater.

[Richard, off-screen] Think of the
dragster's center of mass as the nut.

And the movement of the rear wheels is
your hand turning the spanner.

The higher the center of mass,
the longer the handle

of the imaginary spanner
and the greater the moment.

But the weight of the driver
and car creates a moment that

rotates the dragster about its
back wheel holding it down.

When the turning effect of the
force from the rear wheels

exceeds the effect
of the weight,

it lifts the front of the car.

That's why dragsters have their center
of mass as low as possible.

But wheeling isn't
the only problem.

Dragster engines generate massive power
which is delivered

to the rear wheels.

If one wheel grips more than
the other they don't share the

traction equally so the car will swerve
off course dramatically.

So center
of mass needs to be low.

The problem is things like
engines and drivers mean

that's not always possible.

[Richard, off-screen] In an ideal world,
the center of mass would have been

at this height but that heavy
engine has moved it up,

lengthening that imaginary
spanner and generating too much

of a moment.

It might look like
a fondant fancy,

but physics doesn't care
if you're cool or not.

Too high a center of mass
combined with a powerful engine

results in his best
dying beetle impression.

Just to confirm, he is
celebrating having crashed

on the start line of an
obstacle free track.

Of course, unplanned wheelies aren't
the only problem.

The most powerful dragster engines can
generate 7,000 horsepower.

That's seven times more powerful
than the Bugatti Veyron,

which is like a
really powerful car.

One of the world's fastest.

[Richard, off-screen] That kind of power
needs to be distributed evenly

between the driven wheels

for the car to go
in a straight line.

With the best drag racers
accelerating from naught

to 100 miles an hour
in under a second,

if those wheels experience
uneven traction,

it won't be long before the car
is catastrophically off course.

Like that.

Oh and that.

Of course, a true automotive
scientist can demonstrate

multiple principles
in just one experiment.

Look at that. Excessive moment, followed
by uneven traction.

Who says men can't multitask?

Being extremely
cool I'm always pretty up to

date with the latest BMX moves,
but when someone told me

the latest craze involved
riding on vertical walls,

I accused them of lying.

I had to apologize.

Yes, I'm afraid it's true.
Wall riding is with us.

I strongly advise you not to try
it as it is dangerously stupid.

But if you do
choose to ignore me,

increase your chances of survival by
paying attention to this.

Whilst gravity is
trying to pull you down,

it's thanks to friction created
by your tires on the wall

that you can stay up.

Briefly.

[Richard, off-screen] The rider hops on
to the wall at around 45 degrees

to maximize friction.

Crouching down
against the bike

to increase the time
he can grip.

The friction is never sufficient to keep
the bike up for long.

So for a safe dismount he
hops back off the wall.

So first things first.
Let's get up on the wall.

Remember, the optimum angle
of attack is 45 degrees.

What happens when that
angle is too steep?

[Richard, off-screen] Well, that's what
scientists call riding into a wall.

Okay,
assuming you actually get up,

it's all about
maximizing friction.

A concrete wall, that
should provide some friction.

-[man] Ohh, hoo, hoo.
-[Richard, off-screen] But not for long.

[man] You good?

[Richard, off-screen] Remember, on a
vertical wall friction can only

overcome gravity for
a very short time.

And then you're
always going down.

Okay, I'm going
to let you into a little secret.

There is an easier
way of wall riding.

A curved wall brings a bit of
centripetal force to the party.

[Richard, off-screen]
At last someone's done it.

But it's only possible by the
addition of an extra force.

On a curved surface the bike's
inertia tries to keep the bike

going in a straight line which
pushes the bike into the wall.

This produces centripetal
force and increases the bike's

friction helping it overcome
gravity for longer.

It's the same science that allows
motorcyclists to ride the wall of death.

Centripetal force increases
with speed, so he approaches

at a shallow angle to
maintain momentum.

Simple really.

But not so simple when the
wall isn't actually curved

the whole way around.

His momentum pushed him against
the wall initially,

but once the curve ends, so
does the centripetal force

and the friction.

Quite literally, hit the wall.

So remember, shallow angle of
attack and plenty of momentum.

By angling the bike up the wall,
he loses valuable momentum

and can't benefit from
centripetal force.

If at first you don't succeed
just give up and go home.

The high jump;
a highly trained athlete soars

high into the air before
clearing the bar, which is high.

It is poetry in motion.

[Richard, off-screen] A load of teenage
boys in a tatty old badminton

net in a forest, is
however, a different matter.

That was
undoubtedly indisputably

and monumentally rubbish.

But you know, that comical
scissor motion was once the norm

even for top athletes.

[Richard, off-screen] Yes, straddles and
scissors were all the rage

when the world was
black and white.

But at the 1968 Olympics
everything changed.

d*ck Fosbury won high jump gold
with a new technique

for converting horizontal kinetic energy
into vertical kinetic energy.

Here's how to Fosbury
flop in three easy steps.

[Richard, off-screen] Step one; the
jumper approaches fast and in a curve.

Step two; she plants her leading leg at
an angle of about 35 degrees.

Pivoting on her foot and using
her leg like a vaulter's pole,

to convert horizontal energy into
vertical and rotational energy.

In step three; she gets her center of
gravity high enough to clear the bar.

Okay, let's start with that run up.

Optimum speed for a man is between 23
feet and 26 feet per second.

So speed is important.

But equally important
is technique.

Let's see if
he was paying attention.

Remember horizontal energy
can become vertical energy.

Oh, just not here.

Or here.

Here.

Or indeed here.

Ah, this guy looks like
he knows his stuff.

Appearances can of
course be deceptive.

Remember you can't pivot on your foot if
there's no friction.

Okay, we haven't got off to a great
start. Let's move on to the take off.

[laughter]

[Richard, off-screen] What went wrong?
Well, where do we start?

-Run up too slow.
-[man] Okay, three, two, one.

[Richard, off-screen] And he fails to
use his planted leg as a pivot

and gains no rotation.

Turns out it's not
his fault though.

[man] The high jump that I learned with
was you just kicked a leg up.

And you kind of
flopping into the pool.

[Richard, off-screen] Yeah, it
doesn't work though does it?

[laughter]

[Richard, off-screen] Let's move
briskly along to the flight.

[man] Ohhh! [laughs]

[Richard, off-screen] His center of
gravity was high enough to clear

the bar, which he almost does,
but his bottom wasn't.

And undoes all the good work.

How do you feel?

Okay, I think we've about reached the
pain threshold for this week.

Perhaps you will pause for
thought before flinging yourself

into shallow water, standing on a moving
motorcycle, or cycling up a wall.

Please don't attempt any of the stunts
you've just seen yourself,

because believe it or not, bones break a
lot easier than the laws of science.

Tarrah.

Oh my god!

[music plays through credits]

♪ ♪