07x12 - Mud Bogging, Dancing and Undersized Bikes

[bunniefuu]

[Dallas]
This is the Science of Stupid.

[alarm blares]

[percussive music]

Yes, this is the show
where we attempt

to impose actual sense

onto obvious nonsense.

Prepare yourself to see

foolhardy researchers
try foolish experiments

without fully thinking them through.

We learn our lessons the fun way

whilst they learn the hard way.

Then we reveal what went wrong,

and why,

with the help of such
scientific principles as...

hydrodynamic drag,

- friction...
- [crashing and clattering]

- ...and good old angular momentum.
- [yelling]

In the battle between
fools and physics,

there's only ever one winner.

So watch out--

it's the Science of Stupid.

[electricity crackling]

[glass shatters]

In this show,

we'll be looking
at how dancing in circles

affects your vestibular system,

the importance of angular
momentum in the jump catch...

[man screams]

And the scientific advantages
of flocking.

[girl screams]

But first, this.

[glass shatters]

[electricity crackling]

If you love drag racing
but hate being clean,

then I think I might have
found the sport for you.

[rock music]

It's called mud-bogging.

♪ ♪

This is straight-line swamp racing...

[crowd screaming]

And the rules are simple.

The winner is whoever travels
the furthest distance.

But here's the fun part:

not everyone makes it very far at all.

And if you think this sounds
like the perfect sport for you,

and you'd like to increase
your chances of winning,

then you'd better listen up
to the science.

[dubstep music]

Our man's mud-bogging vehicle

needs to have sufficient suspension

to allow the kinetic energy
from impact to be absorbed,

rather than transferred
to the body of the vehicle.

The tires used for mud-bogging
tend to be large and wide

so that they spread the weight
of the vehicle

over a large surface area,

making it less likely
they'll sink into the mud.

Vehicles with these tires
need to be raised.

However, this gives them
a higher center of mass.

making them less stable.

[crashing]

Okay. So if I've understood
that correctly,

it's all about ensuring you
have good enough suspension,

and if you've raised your truck
to a ludicrous degree,

then being aware of
your high center of mass.

Sounds simple enough,
but have this lot got it?

[brassy music]

This guy has gone for the double:

wide tires and high suspension,

but will it help him conquer the mud?

♪ ♪

[crowd shouting]

Eh, no. No, it won't.

This racer may have wide tires,

but his base of support is too small

for the car's high center of mass.

So when it hits a hole,
the wheels experience drag,

while the top of the car
still has momentum, resulting in...

[thuds]

...an unexpected mud bath.

[crowd yelling and chattering]

It's actually really good for your skin.

Okay, a flatter course and a lower car,

so toppling shouldn't be an issue...

But concussion might be.

[woman] I let it out,
but it still beat me to death.

[Dallas]
This car has short suspension,

which isn't ideal for
traveling in the mud,

so every time it hits a bump,
rather than being absorbed,

the kinetic energy transfers
through the car

and into her head,

and that is another reason

why you should always wear a helmet.

Good, a sensibly-raised truck
with decent-sized wheels.

This should be a master class
in mud-bogging...

[crowd shouting]

And yet here we are.

When this truck lands,
it's angled forward...

which causes the front wheel
to be pushed backwards,

and the suspension can't
compress in that direction.

-[crowd cheering and clapping]
-I'm really not sure

why you're cheering.

[electricity crackling]

[clanking]

The dress codes at weddings
are so complicated nowadays.

Does black tie mean I need
to wear a cummerbund?

Can I wear white and risk
upstaging the bride?

What does "smart casual" actually mean?

It's hard to get it right.

[folk music]

But quite easy to see when
someone's got it wrong.

♪ ♪

And this is very, very wrong indeed.

The Viennese Waltz,
the Lindy Hop,

Strip the Willow--

just a handful of the many
dances that fulfill

our seemingly primal urge
to spin about.

But with so much potential for
spinning ourselves into trouble,

it's best we allow our good friend science

to lead us safety around the dance floor.

[techno music]

As these dancers spin around,

they must take into account
their volume of revolution

to avoid colliding with anything.

The further they are from
the axis of rotation,

the stronger the centrifugal
force they'll experience

pulling them outwards.

And it's worth knowing
that the sensory system

that provides balance
is called the vestibular system.

While spinning, fluid in
the inner ear called endolymph

stimulates hair cells which
tells the brain you're moving.

However, when you stop spinning,

the endolymph continues to move.

This discrepancy is what makes us
feel dizzy.

So, while you may think
you're simply getting into the groove,

you're actually dealing with
volume of revolution,

centrifugal force,

and your own vestibular system,

which might explain why my feet
are always getting muddled.

But let's see if this lot fare any better.

[folk music]

Sweet moves.
She knows how to cut a rug.

When this lady hits the dance floor...

[laughter]

She really hits the dance floor.

It looks like this dancing queen

is spinning barefoot on a smooth floor.

As she twirls,
she experiences centrifugal force,

and without stable footing,

she'll have a sore head in the morning.

[laughter]

[rock music]

Couples dancing now,
and this queen of spin

is taking the lead.

But can her vestibular system keep up?

♪ ♪

[thuds]

Eh, not quite.

As she spins, her vestibular system

sends messages to the brain
that she's moving.

But when she stops,
the endolymph continues to move,

telling her head she's still moving,

which conflicts with what
her legs are telling her.

[dramatic musical flourish]

She'll be fine after a little lie-down.

Ah, good, a dance competition.

[woman screams]

Yeah, well, that's just cheating.

This couple skillfully spin
around a vertical axis,

but unfortunately,

they aren't paying attention
to their volume of revolution,

and that...

-[woman screams]
-Is a no-no.

It doesn't matter how many
sequins you're wearing.

[electricity crackling]

[clanking]

[crumbling]

[Dallas] Yes, it's everyone's
favorite summer activity:

getting mad air on a BMX.

Radical!

But what principle is this biker

about to unwittingly demonstrate?

[glass shatters]

[electricity crackling]

[crumbling]

[Dallas] Did you guess what science
this BMXer was about to show us?

[grunting]

Yeah, of course.
It's the conservation of energy.

The conservation of energy
requires that

he needs to have
enough kinetic energy

when leaving the ramp

to convert into enough
gravitational potential energy

to reach that landing.

He does not,

and it turns out too little air

can leave you winded.

[electricity crackling]

[clanking]

[crumbling]

Here at the Science of Stupid,

we've spent ages searching
for a good way of explaining

how the distribution of mass

can affect the concentration of a load.

[rock music]

And then this helpful lady did this.

[woman yelps]

And we knew she'd cracked it.

[man in French]
Okay?

[Dallas]
And she's just one example.

Alas, it seems adult-sized people

just can't stay away from
child-sized bicycles.

Why?

Well, it's not our place to say,

but it is our remit to reveal

the problematic science therein,

largely material strength,

and the aforementioned
distribution of mass.

[electronic music]

Our man has a much greater mass

than the tiny bike is designed for.

In addition, its small size means

he's forced into an unnatural position,

which puts more strain on the
areas of the bike

than they were designed to take.

In other words, his mass distribution

affects the concentration of the load.

A material strength is dependent on
its cross-sectional area,

so a tiny bike will have lower strength

than a larger bike
made of the same material,

and that can mean--

well, you get the idea.

Get your material strength right

and be aware of your mass distribution,

and this should be child's play,

which is ironic, really.

[man, off-screen]
Don't do it. Don't do it.

[Dallas]
That sounds like good advice,

but I've noticed a theme on this show.

-[clattering]
-[laughter]

And that is, no one ever
takes the good advice.

[laughing]

[man, off-screen]
Are you okay?

[Dallas] The modified bike
here has our friend sitting

with his center of mass high
compared to its wheel base,

so when he attempts a wheelie,
he finds that it...

-[clattering]
-[laughter]

Is a bit too far back.

[laughter]

This dad at a barbecue
is about to teach the kids

a thing or two about showmanship...

Showmanship and mass distribution.

It's a valuable lesson.

Our friend's mass distribution affects
the concentration of the load,

plus there's the fact that
there's too much mass in the first place,

which means...

the material strength is easily exceeded.

Another of the very many issues
with tiny bikes

is that they offer
a smaller base of support

than larger bikes.

So what happens when you
enlarge that base

by giving the bike fatter wheels?

Problem solved, yeah?

[rock music]

[laughter]

Well, not exactly.

This toy motorcycle
has relatively wide and flat wheels,

so it should be a bit more stable,

but it was still designed
for a child.

[laughter]

It's ambitious to go down a large hill
on anything without brakes.

I hope he's got a way to stop.

[clattering]

Ah, phew.

Those fat plastic wheels have
a larger cross-sectional area,

so they have enough material
strength to take his weight,

but what they don't have...

[clattering]

Is very much traction,

unlike his back.

[objects clattering]

[bubbling, hissing]

Okay, settle down, class.

It's time for the science lesson,

that part of the show where we
put one specific principle

under our microscopes,

and there will be a test later,
so pay attention.

Okay, who can tell me what's
being demonstrated by the following?

[girl laughing]

This shop-till-you-dropper...

-[girl screams]
-[laughter]

This Fosbury flopper...

And this floor dropper?

-[man 1, off-screen] You okay, man?
-[man 2] Yeah.

Did you guess they were all
examples of static friction

or lack thereof?

If not, you'll want to pay even
more attention to the science.

Placed on this soapy mat,
it's static friction

that's keeping our inflatable stationary.

That's the force between
its base and the mat.

But the soap means that
static friction is low,

so when it experiences a force,
it doesn't take much

to overcome the static friction,

and then it'll experience
kinetic friction.

The coefficient of kinetic friction
between two objects

is usually lower than the coefficient
of static friction.

In other words,
you don't need as much force

to keep something sliding

as you need to get it sliding
in the first place.

Got that?
Good, as it's time for question one.

What force can stop an object
from sliding?

[jazzy music]

[man grunts]

That's right, it's static friction.

There's low static friction
between his feet and the ice,

so it's relatively easy to overcome.

[man grunts]

And relatively hard
to send that vase back.

Okay, question two:

once you've overcome static friction,

what other type of friction
do you experience?

[light music]

Maybe this bedroom dancer knows.

[thuds]

Yup, it's kinetic friction.

[girl groans]

Doing the running man in your
socks is never a good idea.

Since she's experiencing
kinetic friction,

once her center of mass falls
outside her base of support,

there's nothing she can do
to re-balance herself...

[thuds]

And that isn't a good move.

Last question:
is the coefficient of kinetic friction

lower or higher than the
coefficient of static friction?

[man screaming]

[woman laughing]

That's right, it's lower.

The coefficient of kinetic
friction between two objects

is usually lower,

so once this guy starts sliding,

it's much harder for him to stop.

[woman laughing]

Which is sometimes painful...

[indistinct chatter]

And sometimes painful and expensive.

[woman, off-screen]
Run, Bunty!

[glass shatters]

All right, class dismissed.

[glass shatters]

[electricity crackling]

[crumbling]

[Dallas] In 2013,
the Kumbh Mela pilgrimage

was one of the largest gatherings
of humans in history,

around 30 million people.

In animal terms, that's nothing.

The largest swarm of locusts was estimated
to have over a trillion insects.

That's-- wait, hang on--

more than 130 locusts for every
person on Earth in one swarm,

and that's because some animals
recognize the importance

of sticking together.

[country music]

Whether it's for finding
the best route across an icy path...

[sheep bleating]

[elephant trumpets]

Protecting their young from dangers...

[stampeding]

[chuckling] Or even just having a laugh...

[man, off-screen]
Don't run into our car!

[Dallas]
Things are better together.

[woman laughing]

There are many other reasons
that animals form herds,

flocks or shoals--

increased chances of mating,

protection against predators,

and improving foraging opportunities.

It's exactly the same list that I gave

when they asked why I wanted
to join my local library.

The individual animals in the herd

imitate the behavior of
their closest neighbors.

This allows the entire herd
to respond as a single entity.

This seemingly
coordinated behavior

is mainly due
to the uncoordinated movements

of panicked individual animals.

There's safety in numbers,

as there are more individuals
to spot predators

and less chance of
an individual being eaten.

Herds can also be confident to
chase away certain predators.

So that's the theory,

but how does this all work
in the real world?

This herd of cows is interested
in what that turtle

is doing in their field.

-[man chuckling]
-[cows moo]

They aren't all ninjas, you know.

[cow snorts]

When the turtle nips that cow in the nose,

it backs off in pain.

But its neighbors back off, too,

and that is because
they're imitating each other.

This allows the herd,
or, in this case, flock,

to act as a single entity
moving in the same direction.

It's a useful technique,

unless nobody notices
you've missed your turning.

It's good that they stick together,

as it's impossible to count them
without nodding off.

-[dramatic music]
-[seagulls squawking]

[woman, off-screen]
Don't feed them!

[child shrieks]

[Dallas] Some flocks of birds
form tight V formations

to help conserve energy
by flying in each other's slipstream.

[boy screaming]

But these gulls aren't in any formation;

they're just all after the same snack.

Let's hope it's the ice cream.

Oh, hold on. The little man
might have outpaced them.

[woman, off-screen]
They took it right out of his hand.

[Dallas] It's a good job
that hand isn't vanilla flavored.

[electricity crackling]

[clanking]

I got an email this morning
from a foreign prince

offering me millions if I paid
just a small admin charge.

It sounds amazing,

but if I've learned one thing
in all my years,

it's that there'll be a catch.

There's always a catch.

[upbeat music]

Okay, maybe there isn't always a catch,

but if you are going for a catch,

you'll find...

that they're much harder
than you'd imagined.

Jumping to catch a ball
can be tricky enough,

but add a flip,

and not only will you need
the finely-tuned body of an athlete,

but the finely-tuned mind of a scientist.

[electronic music]

Our catcher must jump with
the right amount of force

and the correct timing

so that his trajectory intersects
with the ball's trajectory.

♪ ♪

For a backflip catch,

he must also generate the correct amount
of angular momentum

to complete a full rotation,

whilst being able to wrap his fingers

around the ball to get a firm grip.

You need the correct timing
and force of jump

so your trajectory intersects
with the trajectory

of the object you're trying to catch,

as well as the appropriate
rotation for your jump.

This should be a piece of cake.

[dubstep music]

You can always make it
trickier by jumping off a roof.

[man grunts, then screams]

But that would be silly.

This guy under-rotates.

This is a good example of what happens

if you don't gain
enough angular momentum

when you're trying to do
a full rotation.

[man screams]

And an excellent example

of why you shouldn't try this yourself.

No roof this time.

Good start.

-[thuds]
-[groans]

But a terrible finish.

[man]
Are you all right, man?

[Dallas] Well, he didn't get enough
angular momentum;

we all know that.

But his trajectory was also nowhere near
the trajectory of the ball,

so he actually failed twice in
quite a short space of time.

If you think about it,
he's an overachiever.

[man groans]

Ah, good. Some professionals.

Lovely angular momentum,

beautiful trajectory,

textbook grip,

slam dunk.

This athlete jumps too far
forward on the trampette

and catches his feet,

giving him angular momentum
as he rotates around it.

Maybe you'd be more suited
to the dive team.

[glass shatters]

[electricity crackling]

[crumbling]

Well, I think that's quite enough of that,

but before we judge the people
you've just seen,

we should remember these words
from Bruce Feirstein:

"The distance between insanity and genius
is measured only by success."

And with that in mind,
I wonder who amongst this lot

is on the very threshold
of a breakthrough.

[lively fiddle music]

[laughter]

[man screams]

♪ ♪

[woman laughing]

-[turtle snaps]
-[man chuckles]

♪ ♪

[woman yells]