03x06 - Drones, Motorbiking and Skiing

[bunniefuu]

[Richard]
This is the Science of Stupid.

[electricity crackling]

Yes, this is the show where we put on
the rubber gloves of science

and pick up a great big pile of stupid,
so we can take a close scientific look

at what these people seem to be
getting wrong.

It might be their velocity,

possibly angular momentum,

or maybe they've forgotten
all about trajectory.

But luckily, we haven't.

So welcome
to the Science of Stupid.

[electricity crackling]

In this show, we'll explore acceleration,

center of mass,

and friction, or lack of it.

But first this.

[glass shatters]

[electricity crackling]

You know, you often hear people say,
"Ooh, don't jump.

You might hurt yourself"?

But when you think about it,
that's nonsense.

Jumping never hurt anyone.

Landing, on the other hand...

-[laughter]
-[man] Ohh!

[Richard] ...that's a little different.

-[laughter]
-[man] Ohh!

[Richard] There are three golden rules
to landing safely.

Rule one: Look before you leap.

Although that was less leaping
and more falling over.

Rule two: Soft landings are always best.

[Richard] Oh! That was probably too soft.

And finally, rule three...

[boy] Ohh. [laughs]

[Richard] ...the ground is not
your friend.

[boy] Ohh. [laughs]

[Richard] If you were planning
on a dramatic leap in the near future,

perhaps best to try and nail
that perfect landing.

Fortunately, science is on hand
with a little damage limitation.

It's largely down to absorbing
ground reaction force.

Unsurprisingly, that's the force
you generate when you hit the ground.

[quirky electronic music]

He sets his launch, angle, and velocity
to determine his trajectory.

Whilst in the air,
he's constantly accelerating downwards.

So to absorb as much reaction
force as possible,

he adjusts his body to land
on the ba*ls of his feet.

♪ ♪

And flexes his ankles, knees and hips.

By then rolling forwards,
he loses momentum

over a longer period of time,
decreasing the impact force.

♪ ♪

Got that?
Be careful where you jump.

Bend your legs and roll if you can,
because for every second you fall,

gravity is going to accelerate you
downwards at nearly 22 miles an hour.

So shall we start with trajectory?

Thank you.

Next...

do you think he's practiced that?

No, me neither.

Nice trajectory, but legs
not in an ideal position for landing.

Let's see if three minds
are better than one.

[all] Ohh!

[Richard] In their case,
I'd say that's a no.

Although their legs were bent,
they couldn't control their landing,

meaning the ground reaction force
was absorbed

in a less than desirable area.

Let's try it without the bench.

Interesting, but completely wrong.

Legs absorb very little force.

Face... quite a lot.

Shall we move on to the body roll?

[man] Don't do it!

[Richard] You don't want to listen to
them.

[all] Ohh!

[Richard] Or maybe you do.

And the body roll ends to work
best after you land.

There's one final technique
wehaven't touched on,

and that is to get your friends
to help you.

Oh, dear.

His friends would have absorbed
the force of his fall better

if they'd stayed here

instead of moving to here.

[electricity crackling]

If I tried to sell you a vehicle
that won't go much faster

than walking pace,
doesn't have a seat,

and every journey
involves the risk of injury,

I'm guessing your answer would
involve the words "no" and "idiot,"

but such a thing does exist,
and it's called a hoverboard.

It's an odd name for something with wheels
that doesn't actually hover.

But the other stuff I said is true.

Especially the risk of injury.

[woman] Whoo.

I'm really hurt!

[man, off-screen] I don't think I got
the whole impact though.

[Richard] Oh, I'm sure
she won't mind doing it again.

[woman] Whoo.

[Richard] In case you're sitting there
thinking you've just seen

the future of transport
and now would be a good time

to sell the car, may I direct
your attention towards the science?

Hoverboards have a motor for each wheel,

which is operated by tilting
the foot pad back or forward.

With a rider,
they form an inverted pendulum

which has the center of mass of the person

balanced above the pivot point,
the wheels.

When he leans forward,
to stop him toppling,

the wheels must accelerate
in the same direction

fast enough to compensate.

Done correctly,
it's called dynamic equilibrium.

Done incorrectly, it's called... painful.

So it's all about controlling
that balance and momentum.

The trick is to shift your body weight
forward gradually to pick up speed

rather than just lunging forward.

So no sudden moves.

[woman] Ahh! [laughs]

[Richard] Yeah,
that was definitely suddenish.

A little bump caused that
precarious center of mass

to move too far around her pivot point,
unbalancing her.

[woman laughs]

[Richard] Let's try lowering
the center of mass.

Don't look at me, mate.

Or that'll happen.

[boy] Daddy!

[Richard] By shortening
the length of the pendulum,

it should make it easier to balance,

in theory.

Okay, what we really need is an expert.

[man]
The score is if you go back...

...and just forward.

Then suddenly--

[laughter]

[Richard] Which he isn't.

Otherwise, he would have known
that if his right wheel loses traction,

his hoverboard will turn right,

but his momentum
will keep him going forwards.

If you fancy more of a challenge,
why not multitask?

[man] Right, let's, er...

...stop doing that.

[Richard] No, but maybe
don't stop quite so quickly.

[man] Oh...ohh. Ohh.

[Richard] Does anyone know first aid?

[groans]

[Richard] I'll take that as a no.

If you are still tempted to buy one,
beware.

Not all items you see advertised
will be an authentic hoverboard.

Nice center of mass, though.

[electricity crackling]

[engine revving]

Can you guess what scientific principle
is about to occur?

[glass shatters]

[electricity crackling]

So have you guessed
what science we're about to see?

It's angular momentum
and maybe something else?

Oh, look out!

Yes, impact force.

Here, the snowmobile's forward momentum
is turned into angular momentum.

And here another snowmobile
gives us the impact force.

Or rather, gives it to him.

[electricity crackling]

When someone says to me, "Nice dribbling,"

it's usually because I've fallen asleep
with my mouth open again.

But if I'd played basketball,

I could at least pretend they were
trying to pay me a compliment.

[upbeat music]

Yes, if you have them,

dribbling skills can make you
look super cool.

Trouble is not everyone does.

To help you
avoid an unwanted DIY nose job,

we thought it only right and proper

to explain how science
can help with your basketball dribbling.

For a high-frequency bounce,

he keeps the ball low and keeps
the angle of incidence small,

for a small angle of reflection.

He pushes hard from the fingertips
so the ball deforms more on impact,

storing more elastic potential energy

and converting it into more kinetic energy
and velocity.

By combining sleight of hand
with frequency and velocity,

he can exploit his opponent's
reaction time and dribble past.

Got all that?
Keep low, bounce fast,

and hope your reactions
are quicker than your opponent's.

So let's start with our angles.

Angle of reflection, zero degrees.

Angle of legs, 180 degrees.

[man, off-screen]
What happened, bro?

[Richard] You just did something
men aren't designed for.

Keeping his angle of incidence
equal to zero

enables this chap
to bounce two ba*ls blindfolded.

Did you know that the record for dribbling
a basketball is over 55 hours?

This could take some time,
so shall we move on to the bounce?

His bounce seemed a little high.

[man] Listen to...

[Richard] As was the pressure of his ball.

His bounce height is very low,

giving the smart, young student
less time to react.

[crowd] Ohh.

[Richard] Well, he's probably
better at maths.

[man] This brother think he can dunk on
me, I'm gonna show this defense, though.

[Richard] Yeah, whatever he said.

[crowd] Ohh. [laughs]

[Richard] I don't think he said that.

Short, fast bounce confuses opponent.

But poor shot at the basket,
and big center of mass issue.

[man laughs]

[man, off-screen] I got that!

I got that!

[Richard] Yeah, we know.

[man 2, off-screen]
Cameras off! Cameras off!

[Richard] Bit late for that, mate.

[man 3, off-screen] You good, cuz?

[Richard] And finally, make sure
you're the only one

who wants to do a spot of dribbling.

[bell rings]

It's that time in the show when we give
your intellectual envelope a gentle push

with a good old-fashioned science lesson.

Can you figure out today's theme
from the following?

A big bloke in front of a motorbike.

A winter sports holiday...

slash, road trip.

And a not-so-super superhero.

[man, off-screen]
Wait, where are you going?

[Richard] Nowhere now.

[man, off-screen] He's hurt.

[Richard] Yeah, that would make sense.

A gold star for anyone that said friction.

This is the force that resists
one surface sliding over another.

But of course
there's more to it than that.

And who better to demonstrate
the finer details

than a man wielding an angle grinder?

Friction is caused by asperities,

microscopic bumps
found on almost any surface.

When friction is high between
moving surfaces,

kinetic energy is transformed
into lots of heat.

And since friction is proportional
to the amount of force pressing down,

the heavier something is,
or the harder it's pushed,

the more friction and heat
it will generate.

Right, I hope you were listening,
because it's time for a test.

Question one: If a surface
is very smooth with few asperities,

will it have high or low friction?

That's right, low friction.

Are you off?

Oh, you missed a bit.

[man speaking French]

[Richard] This French gentleman
has decided to go paddling.

[man] Let's go!

[Richard] And now, swimming.

Unfortunately, smooth,
wet rocks have fewer asperities

than rough ones,
so they give less friction.

[woman, off-screen]
Oh, he's hurt himself!

Go and help him!

[Richard] Is it just me, or has
French fashion lost its way a little?

[exhales]

[Richard] Question two:

As well as the roughness of the surfaces,
what else is friction proportional to?

[quirky music]

Yes, the force pressing down.

Here this chap is exerting a lot of force
on this playground gym equipment,

and it's through friction that the hoop
grips the bar,

but with less force,
there is less friction.

Maybe try the swings instead.

Let's apply this to a home environment.

[laughter]

[Richard] He's a big lad for eight.

Initially, his hands were applying
more force, creating more friction.

By releasing that force,
friction was reduced.

[laughter]

[woman, off-screen] That's not funny,
that must've hurt.

[Richard]
That's why he thinks it's funny.

And finally, question three:

When friction is high,
what is kinetic energy converted into?

That's right, heat.

To glow bright red, steel must reach
over 1,200 degrees Fahrenheit.

[man, off-screen] Yeah!

[Richard] For skin, slightly lower.

[man] Augh!

[Richard] Not burning rubber;
that's burning blubber.

That's really not a good idea.

[man] It sucks so bad!

[Richard] Yeah, this could
seriously damage your health.

And that concludes
our science lesson on friction,

which is sometimes your friend,
but quite often... not.

[glass shatters]

[electricity crackling]

Do you like the idea
of traveling at high speed

over which you have no control,

then being propelled
into a large expanse of cold water

with the distinct possibility
of personal injury?

Yeah, it does sound great, doesn't it?

[upbeat music]

[man laughs]

[Richard] Actually, can I change my mind?

What might initially look like fun,

once you introduce a ramp,

doesn't look quite so much fun.

And it's not just jumping
that can give you pain issues.

There's also rail grinds.

[man] Ohh.

[Richard] Although he's decided
to grind something else.

[man 2, off-screen] Are you OK?

Whether you're on water skis
or wakeboards,

managing that takeoff ramp
can be a little troublesome.

Shall we see if science
can help sort it out?

First, he arcs sideways,
making use of centripetal force

from tension in the cable
to increase velocity.

The greater his velocity,
the more height he will get,

and the more air time
he'll have for a flip.

He then lands
with the back of the board down first

and with his knees bent
to absorb the impact force.

So it would seem that the key thing here

is having enough speed
when you hit the ramp.

Looking good. All we need to do now
is accelerate.

Or not. Please yourself.

Not enough speed,

rope catches ramp,

and somersault trick
spoiled by skis not staying on feet.

Is there anything he did get right?

Er, no, don't think so.

[woman, off-screen] Go Dan!

[Richard]
I'm guessing this is Dan.

[all] Ohh.

[man, off-screen]
He's all right!

[Richard]
I think Dan got that a bit wrong.

Whilst he did accelerate, it was,
sadly, into the side of the ramp.

Did he mean to do that?

Grinding is a bit like jumping,
but with a bit more friction thrown in.

So shall we see if it makes a difference?

Well, that was...
What's the word I'm looking for?

[man, off-screen]
Awesome!

[Richard] No, that's not it.

If he'd been going a bit faster,

he might have cleared
the edge of the pipe,

but he wasn't.

And he didn't.

[man, off-screen]
Are you all right bud?

[man 1] Yeah, yeah.

My hands hurt.

[Richard] Yeah,
I've just been explaining why.

Let's hope this fella's
not a mate of Dan's.

-[woman gasps]
-[man laughs]

[woman, off-screen]
Did you get that on video?

[Richard] Yes, shall we look at it again?

Once again, not enough speed,

but this time by catching an edge,
it gave him angular momentum,

which he took full advantage of.
Clever chap.

[electricity crackling]

In 1895, American inventor Jesse Reno
unveiled the world's first escalator,

which means we've now had over 120 years
to learn how to use them properly.

[woman laughs]

[Richard] And that's not how.

[man, off-screen] She's made 6 inches
in the last 25 seconds.

[Richard] Which I make
roughly 0.01 miles an hour.

Hope she hasn't parked on a meter.

But there are people who have turned
not using an escalator properly

into something of an urban sport,
and it's called escaloptering.

[man, off-screen] Dude.

[Richard] Sorry, did I say sport?

I must have
been thinking of something else.

[man, off-screen]
That's incredible, man!

How are you doing that?

Well, that's precisely
what we're here to answer.

So let's have a look
at the science of escaloptering.

To escalopter, he uses two handrails
moving with equal and opposite velocity.

These combine with friction
to provide a force cup,

which will rotate him.

The flatter and more rigid his body,
the more efficiently he will rotate.

Contact with both rails
must be kept at all times,

particularly tricky
if the rails are too far apart.

So it's all about making sure
that the two forces

are evenly and constantly applied.

Easy to say, but let's see
if it's as easy to do.

[man, off-screen] And go!

[man laughs]

Did you hit your head?

[Richard] Yes, she did.

Because her body wasn't rigid enough

and her petite posterior
fell between the rails.

Let's try with a larger one.

[glass shatters]

[Richard] I'm saying nothing.

This guy's also having trouble
keeping rigid.

But I'm sure he won't repeat
the same mistake twice.

[bleep]

[Richard] Oh, no, he's made a new
mistake.

[man, off-screen]
Are you doing good?

[Richard] By not lying
on the flat part of the rail,

his center of mass
moved outside his base of support.

And now gravity...

has given him a little souvenir.

[man]
You're bleeding, man!

[Richard] Makes a change
from a novelty tea towel, I suppose.

[glass shatters]

[electricity crackling]

The next time you feel a sudden urge
to do something dangerous,

I suggest you stop and think
about the science,

just to make sure you're not about to
do something incredibly stupid.

Good-bye.

[all] Ohh!

[man laughs]

[man] Ohh.