Science of Stupid (2014) s08e14 Episode Script
Kite Surfing, Rollerblading and Compressed Air
1
DALLAS (off-screen): This
is the Science of Stupid.
Yes, this is the show that
finds the science hidden in
the stupid.
Watch as the scientifically
ignorant discover what the
rest of us already know
that physics always wins.
We'll study what went wrong
and why with the help of
scientific principles
like terminal velocity,
hydrodynamic drag and,
series favorite,
axis of rotation.
Take on science at your own
risk, you have been warned.
It's the Science of Stupid.
In this episode we'll be
discovering how you can use
kinetic energy to get
more room in the bed.
We'll be learning the
advantages of angular velocity,
the hard way, and
giving you a master class in
how to start kite surfing,
or at least how
not to but first this.
Shopping during the sales
is a competitive business,
to win you go in hard and don't
let anything get in your way.
How much for the pink dress,
the one with the tire mark?
Where our keen bargain hunter
has gone wrong was that she
hadn't mastered the art of
acceleration and deceleration
on her scooter, and it's not
surprising because it's not
just an art.
It's a science.
Turning a scooter's throttle
delivers extra power to the
wheel, allowing
it to accelerate.
Braking applies friction to
the wheels which causes the
bike to decelerate.
Sufficient friction between
the tires and the road is
essential for acceleration
and deceleration,
and as long as the rider
is holding on tight enough
they'll act as one unit but
if they do become separated
inertia will try to keep the
rider moving in a straight
line, regardless of
what the bike does.
So, it's throttle
to accelerate,
friction at the brakes to slow
down and friction at the road
to make the first
two possible.
Oh and whilst crashing can be
a faster way to stop it's not
an advisable method.
Okay, science learnt.
Let's go shopping.
For a new fence.
This nervous rider, hiya.
Appears to know where the
throttle is but doesn't seem
to know how to steer
or use his brakes.
Putting his foot down doesn't
provide as much friction as
braking would have but luckily
the fence provided all the
deceleration he needed.
Thankfully he wasn't
traveling fast.
Unlike him.
As we learnt, it's best to
decelerate using the gradual
friction method, i.e. brakes,
and not the impact force
method, i.e. crashing.
The flexibility of the barrier
reduced the impact force
experienced by the rider but
it still looked painful.
There's no barriers here,
except that one.
Our rider hits the brakes but
there's insufficient friction
between his tires and the
road so he skids and can't
decelerate in time.
So, the car applies a
force to his scooter,
rapidly decelerating
it but not him.
Thankfully both drivers were
fine and they each learnt a
valuable lesson about inertia.
So, as long as you
remember, throttle control,
braking rather than crashing
and maintaining good contact
with the road a
scooter is your friend.
But not his.
Now then, this is the point in
the show where we take a break
from the ill-advised and look
at the truly magnificent,
and you can't get more
magnificent than this.
These wheelchair athletes are
going to try and set a new
world record by pulling these
three trucks weighing an
incredible 110,407.5 pounds
over 328 feet.
And that is it.
A new world record.
Well done, team.
The reasons this team could
achieve this amazing feat were
dedication, drive,
physical prowess
and a mastery of inertia.
To tow an object you need to
apply a force large enough to
overcome its inertia, which
is proportional to its mass.
Friction between the object
and the surface can make
towing harder but adding
wheels provides rolling
friction, which offers
less resistance,
and the puller or pullers need
friction with the ground to
get a reaction force to
move the object forwards.
Apply enough force to overcome
an object's inertia and make
sure the friction isn't too
high for the thing being
pulled or too
low for the puller.
Alright, which of our trainee
record breakers can put the
aforementioned
theory into practice?
Not that one.
Our muscly friend applies
enough initial force to
overcome the heavyweight
inertia and friction with the
ground until the strap breaks.
So, how do we
make this easier?
Oh, maximum science
points, Dad.
Snow, low is the friction
between the ground and the
mass he's towing, or children,
allowing him to easily
overcome their inertia.
Of course, there is another
way of making that easier.
MAN (off-screen):
Watch the tree.
DALLAS (off-screen):
Oh! Yes, that's right, Dad.
By losing mass.
Okay, let's forget the
snow and try some wheels.
Lots of wheels.
MAN: Oh.
DALLAS (off-screen): Lots
of wheels but not helmets.
The cyclist can easily pull
the skateboard as its wheels
give it low rolling friction
but when he leans too far back
and his center of mass falls
outside of his base of support
the wheel's low rolling
friction causes the board to
fly forwards and him
to stop for a snack.
MAN: He ate the kerb.
DALLAS (off-screen):
Speaking of snacks.
Our friend here can pull the
heavy fridge because his
bike's grippy tires create
enough friction with the road
whilst the casters under
the fridge provide rolling
friction, which offers
little resistance.
I don't know what
you're looking at mate,
we all get a bit
peckish when we cycle.
So, there you go, breaking the
vehicle towing record is all
about overcoming inertia.
And occasional dogs.
I'm sure we've all got one of
these corn strippers at home
but can you guess what science
this young cob spinner wants
to demonstrate?
DALLAS (off-screen): Now
then, did you work out the scientific principle he was
keen to show us?
Yes, it's torque.
By applying force at distance
to the axil the young corn
enthusiast can produce a large
amount of torque to turn the
machine, however when he steps
too close and the handle gets
underneath him the momentum
of the machine applies enough
torque to overcome his weight
and take him for a ride.
Maybe just buy it
in a tin next time.
I love kites and I love
surfing so I thought to
myself, "Why not
learn kite surfing?"
What's not to love?
Apart from that.
It turns out that even just
learning to control that kite
on the beach is
complicated enough,
so how about a crash
scientific course on the
basics of kite surfing?
Starting with what
kite surfers call
the "wind window."
The wind window is a
three-dimensional arc of sky
downwind of a surfer in which
the kite is able to fly,
directly downwind of the
surfer is the power zone where
the kite generates
maximum power.
At the edge of the window the
kite produces the least amount
of power.
Whilst water offers low
resistance to movement the
surfer experiences increased
resistance from the land,
which combined with the power
from the kite generates a
large turning effect,
which he should lean back
to counteract.
To help them keep control kite
surfers are taught to launch
their kites at the edge of the
wind window where they won't
be hit with an
overload of power.
Sounds simple enough but it
takes quite a lot of practice.
This young scientist is
learning kite control on the
edge of the power zone.
MAN: Oh.
DALLAS (off-screen):
Learning, not learnt.
As he dives the kite into the
power zone its power increases
substantially and he
can't resist the pull.
Thankfully his friends
were there to help
and by "help" I am of
course being sarcastic.
Let's try with two
people holding, shall we?
MAN: No, no!
DALLAS (off-screen):
See, much more secure.
Where's she going?
MAN: Are you alright?
WOMAN: Yeah.
DALLAS (off-screen): The kite
was launched directly into
the heart of the power zone,
so it generated more power
than she could keep up with.
Lesson learnt.
MAN: Whoa, whoa, whoa.
DALLAS (off-screen): Oh,
she's off for an ice cream.
Water offers less resistance
to motion than land so he can
take advantage of
the pull of the kite.
MAN: Agh.
DALLAS (off-screen):
Until he hits land again.
Next time keep an
eye out for terra firma
and unexpected sea dogs.
Close one.
When it comes to crossing
rivers some people prefer
boats, others bridges.
Personally I find both boring,
I much prefer stepping stones.
They're much
more fun to spectate.
Our friend there broke the
first rule of stepping stone
stepping, that is to
ensure that the stone,
or platform to be
stepped on, is sturdy and not floating about.
He also broke pretty much all
the other rules as set out by
the following
scientific steps.
The stepping stones must
be dry enough to provide
sufficient friction to
prevent him slipping.
He must land with his
center of mass close to his
base of support,
this ensures his
feet do not apply too much
horizontal force, which could
risk overcoming friction with
the stepping stone.
Lastly, even shallow slow
running rivers can be
deceptively dangerous places.
So, another critical rule
is to check that the body of
water and crossing platforms
have been designated as safe
by the relevant authority.
Alright, science
taught but was it learnt?
No.
To start with the river is
fast flowing and clearly
dangerous, the angle of
the scope made the launch
difficult, the low friction
between his feet and the mud
made is non-existent.
Where's your phone?
Oh, ah.
He's like a mountain goat,
a mountain goat that's
just fallen into a river.
When he lands on the last rock
his center of mass is too far
behind his base of support,
so his feet applied a large
horizontal force which
overcomes the friction the
rock can offer.
Luckily the fall was broken
by the ice cold raging torrent.
Okay, it's flat.
MAN: Come on, man!
MAN: It's not that easy.
DALLAS (off-screen): Relatively
dry and it's a small gap.
We've got this.
Yes, yes.
No.
MAN: Oh my goodness.
DALLAS (off-screen):
No, we haven't.
He made the jump but due
to his heavy backpack his
center of mass is, again,
behind his base of support
and so he falls backwards.
Grabbing the branch would
have been a good idea if it had
been attached to something.
This adventurer's not even
bothering, he's just wading,
unlike his friend
who's swimming.
It's only a small step but
the landing stone has been
lubricated by the
water so has a very low
coefficient of friction,
almost as low as his face.
DALLAS: Air is a remarkable
substance, not only does it
allow us to breathe,
which I think we can all agree is a good thing,
but if you compress it and
contain it you can have loads
of fun.
Like defying
the laws of physics
or for whacky furniture.
Whack, see.
The secret to understanding
and using compressed air is to
realize that all it wants to
do is stop being compressed air.
It wants to escape and in so
doing air teaches us valuable
science on
pressure differentials
and conservation of energy.
If air in one part of a
container is compressed it
will apply pressure to all
other parts until all areas
are the same pressure, this is
due to conservation of energy.
When a container of compressed
air is open to the atmosphere
the high pressure inside
equalizes with the lower
pressure outside, producing
a force as the air escapes
and whatever is containing
the compressed air needs to have
the material strength to
withstand the pressure
differential,
otherwise it will fail.
To sum up, pressure changes
will be transferred to all
parts of the container, give
something at high pressure an
opening and it will take
it and escape with force,
and finally whatever you do
make sure the container you're
using is strong enough.
So, now you know but
do our researchers know?
WOMAN: Don't break my bed!
DALLAS (off-screen):
Yes, they do.
The jumper has cleverly
demonstrated a basic
pneumatic system.
He adds kinetic energy
with his jump which causes a
pressure change in the bag and
due to conservation of energy
the kinetic energy is
transferred to her and she
then transfers that same
energy to the bedside table
via her head.
MAN: Are you OK?
DALLAS (off-screen):
How about something a little more high tech?
Surely these
amateur rocket engineers
understand pneumatics.
Ah, turns out they don't.
The young researcher was
trying to compress air by
jumping on the pump.
Unfortunately he misses.
WOMAN: Oliver!
DALLAS (off-screen):
But Oliver doesn't.
When the pump is pressed the
pressure differential created
applies a force that
launches the rocket.
WOMAN: Oliver!
DALLAS (off-screen): Good to get
a closer look at the physics.
Understanding the science
allows you to take advantage
of the science, like
building a beach trampoline.
Fun times.
MAN: Oh.
DALLAS (off-screen):
Yeah, less fun times.
The membrane of the beach
ball didn't have the material
strength to contain the higher
pressure produced by our more
short-footed researcher.
We can all use science
to elevate the ordinary.
A case in point, you could
just rollerblade or you could
use angular momentum to add
a little something extra and
make it a bit special.
You see. Special.
Now, what our young friend was
attempting was a rollerblade
flip and the reason he failed
was that he hadn't studied
angular momentum,
angular velocity or even
moment of inertia.
Luckily you can.
First he needs sufficient
take-off velocity for enough
height and air time
to perform the flip.
As he launches he leans to
generate angular momentum.
He then tucks in, decreasing
his moment of inertia,
which increases his
angular velocity,
meaning he spins faster
and completes his flip.
Angular momentum, the momentum
you have when you're spinning
cannot be changed
once you've launched.
Angular velocity, your spin
speed, can be changed mid-air,
as we've seen by
tucking in or decreasing
your moment of inertia.
Get all that right and you
can flip backwards or forwards.
Whether you want to or not.
(screams)
This skater wasn't trying to
add a flip but his one-foot
take-off gives him
unexpected angular momentum and
an unintentional
90-degree rotation.
MAN: Ow.
DALLAS (off-screen): Now,
this researcher is trying to
add a flip.
But he probably
wishes he hadn't.
He doesn't tuck in to reduce
his moment of inertia and so
doesn't have sufficient
angular velocity to complete
the turn but if he wanted
to smack his back on the floor.
It was textbook.
MAN: Oh.
DALLAS (off-screen): That's
better but that's worse.
Even though he had good speed
at take-off he holds his tuck
too long and so has too
much angular velocity.
He should have extended his
body earlier to increase his
moment of inertia
but instead he just extended
his dental work.
MAN: Oh.
DALLAS (off-screen): Okay,
good speed, great spin.
WOMAN: Yes.
DALLAS (off-screen):
Just the finish to go.
MAN: Yeah.
DALLAS (off-screen): Yeah, he
definitely meant to do that.
And that is it.
We have run out of time but
unfortunately not stupidity.
So, please do not copy any of
the dangerous stunts you have
just seen.
As Bill Nye the
Science Guy once said,
"Science is the best
idea humans have ever had."
Sorry Bill, I guess
this lot missed that class.
♪
♪
Captioned by
Cotter Captioning Services
DALLAS (off-screen): This
is the Science of Stupid.
Yes, this is the show that
finds the science hidden in
the stupid.
Watch as the scientifically
ignorant discover what the
rest of us already know
that physics always wins.
We'll study what went wrong
and why with the help of
scientific principles
like terminal velocity,
hydrodynamic drag and,
series favorite,
axis of rotation.
Take on science at your own
risk, you have been warned.
It's the Science of Stupid.
In this episode we'll be
discovering how you can use
kinetic energy to get
more room in the bed.
We'll be learning the
advantages of angular velocity,
the hard way, and
giving you a master class in
how to start kite surfing,
or at least how
not to but first this.
Shopping during the sales
is a competitive business,
to win you go in hard and don't
let anything get in your way.
How much for the pink dress,
the one with the tire mark?
Where our keen bargain hunter
has gone wrong was that she
hadn't mastered the art of
acceleration and deceleration
on her scooter, and it's not
surprising because it's not
just an art.
It's a science.
Turning a scooter's throttle
delivers extra power to the
wheel, allowing
it to accelerate.
Braking applies friction to
the wheels which causes the
bike to decelerate.
Sufficient friction between
the tires and the road is
essential for acceleration
and deceleration,
and as long as the rider
is holding on tight enough
they'll act as one unit but
if they do become separated
inertia will try to keep the
rider moving in a straight
line, regardless of
what the bike does.
So, it's throttle
to accelerate,
friction at the brakes to slow
down and friction at the road
to make the first
two possible.
Oh and whilst crashing can be
a faster way to stop it's not
an advisable method.
Okay, science learnt.
Let's go shopping.
For a new fence.
This nervous rider, hiya.
Appears to know where the
throttle is but doesn't seem
to know how to steer
or use his brakes.
Putting his foot down doesn't
provide as much friction as
braking would have but luckily
the fence provided all the
deceleration he needed.
Thankfully he wasn't
traveling fast.
Unlike him.
As we learnt, it's best to
decelerate using the gradual
friction method, i.e. brakes,
and not the impact force
method, i.e. crashing.
The flexibility of the barrier
reduced the impact force
experienced by the rider but
it still looked painful.
There's no barriers here,
except that one.
Our rider hits the brakes but
there's insufficient friction
between his tires and the
road so he skids and can't
decelerate in time.
So, the car applies a
force to his scooter,
rapidly decelerating
it but not him.
Thankfully both drivers were
fine and they each learnt a
valuable lesson about inertia.
So, as long as you
remember, throttle control,
braking rather than crashing
and maintaining good contact
with the road a
scooter is your friend.
But not his.
Now then, this is the point in
the show where we take a break
from the ill-advised and look
at the truly magnificent,
and you can't get more
magnificent than this.
These wheelchair athletes are
going to try and set a new
world record by pulling these
three trucks weighing an
incredible 110,407.5 pounds
over 328 feet.
And that is it.
A new world record.
Well done, team.
The reasons this team could
achieve this amazing feat were
dedication, drive,
physical prowess
and a mastery of inertia.
To tow an object you need to
apply a force large enough to
overcome its inertia, which
is proportional to its mass.
Friction between the object
and the surface can make
towing harder but adding
wheels provides rolling
friction, which offers
less resistance,
and the puller or pullers need
friction with the ground to
get a reaction force to
move the object forwards.
Apply enough force to overcome
an object's inertia and make
sure the friction isn't too
high for the thing being
pulled or too
low for the puller.
Alright, which of our trainee
record breakers can put the
aforementioned
theory into practice?
Not that one.
Our muscly friend applies
enough initial force to
overcome the heavyweight
inertia and friction with the
ground until the strap breaks.
So, how do we
make this easier?
Oh, maximum science
points, Dad.
Snow, low is the friction
between the ground and the
mass he's towing, or children,
allowing him to easily
overcome their inertia.
Of course, there is another
way of making that easier.
MAN (off-screen):
Watch the tree.
DALLAS (off-screen):
Oh! Yes, that's right, Dad.
By losing mass.
Okay, let's forget the
snow and try some wheels.
Lots of wheels.
MAN: Oh.
DALLAS (off-screen): Lots
of wheels but not helmets.
The cyclist can easily pull
the skateboard as its wheels
give it low rolling friction
but when he leans too far back
and his center of mass falls
outside of his base of support
the wheel's low rolling
friction causes the board to
fly forwards and him
to stop for a snack.
MAN: He ate the kerb.
DALLAS (off-screen):
Speaking of snacks.
Our friend here can pull the
heavy fridge because his
bike's grippy tires create
enough friction with the road
whilst the casters under
the fridge provide rolling
friction, which offers
little resistance.
I don't know what
you're looking at mate,
we all get a bit
peckish when we cycle.
So, there you go, breaking the
vehicle towing record is all
about overcoming inertia.
And occasional dogs.
I'm sure we've all got one of
these corn strippers at home
but can you guess what science
this young cob spinner wants
to demonstrate?
DALLAS (off-screen): Now
then, did you work out the scientific principle he was
keen to show us?
Yes, it's torque.
By applying force at distance
to the axil the young corn
enthusiast can produce a large
amount of torque to turn the
machine, however when he steps
too close and the handle gets
underneath him the momentum
of the machine applies enough
torque to overcome his weight
and take him for a ride.
Maybe just buy it
in a tin next time.
I love kites and I love
surfing so I thought to
myself, "Why not
learn kite surfing?"
What's not to love?
Apart from that.
It turns out that even just
learning to control that kite
on the beach is
complicated enough,
so how about a crash
scientific course on the
basics of kite surfing?
Starting with what
kite surfers call
the "wind window."
The wind window is a
three-dimensional arc of sky
downwind of a surfer in which
the kite is able to fly,
directly downwind of the
surfer is the power zone where
the kite generates
maximum power.
At the edge of the window the
kite produces the least amount
of power.
Whilst water offers low
resistance to movement the
surfer experiences increased
resistance from the land,
which combined with the power
from the kite generates a
large turning effect,
which he should lean back
to counteract.
To help them keep control kite
surfers are taught to launch
their kites at the edge of the
wind window where they won't
be hit with an
overload of power.
Sounds simple enough but it
takes quite a lot of practice.
This young scientist is
learning kite control on the
edge of the power zone.
MAN: Oh.
DALLAS (off-screen):
Learning, not learnt.
As he dives the kite into the
power zone its power increases
substantially and he
can't resist the pull.
Thankfully his friends
were there to help
and by "help" I am of
course being sarcastic.
Let's try with two
people holding, shall we?
MAN: No, no!
DALLAS (off-screen):
See, much more secure.
Where's she going?
MAN: Are you alright?
WOMAN: Yeah.
DALLAS (off-screen): The kite
was launched directly into
the heart of the power zone,
so it generated more power
than she could keep up with.
Lesson learnt.
MAN: Whoa, whoa, whoa.
DALLAS (off-screen): Oh,
she's off for an ice cream.
Water offers less resistance
to motion than land so he can
take advantage of
the pull of the kite.
MAN: Agh.
DALLAS (off-screen):
Until he hits land again.
Next time keep an
eye out for terra firma
and unexpected sea dogs.
Close one.
When it comes to crossing
rivers some people prefer
boats, others bridges.
Personally I find both boring,
I much prefer stepping stones.
They're much
more fun to spectate.
Our friend there broke the
first rule of stepping stone
stepping, that is to
ensure that the stone,
or platform to be
stepped on, is sturdy and not floating about.
He also broke pretty much all
the other rules as set out by
the following
scientific steps.
The stepping stones must
be dry enough to provide
sufficient friction to
prevent him slipping.
He must land with his
center of mass close to his
base of support,
this ensures his
feet do not apply too much
horizontal force, which could
risk overcoming friction with
the stepping stone.
Lastly, even shallow slow
running rivers can be
deceptively dangerous places.
So, another critical rule
is to check that the body of
water and crossing platforms
have been designated as safe
by the relevant authority.
Alright, science
taught but was it learnt?
No.
To start with the river is
fast flowing and clearly
dangerous, the angle of
the scope made the launch
difficult, the low friction
between his feet and the mud
made is non-existent.
Where's your phone?
Oh, ah.
He's like a mountain goat,
a mountain goat that's
just fallen into a river.
When he lands on the last rock
his center of mass is too far
behind his base of support,
so his feet applied a large
horizontal force which
overcomes the friction the
rock can offer.
Luckily the fall was broken
by the ice cold raging torrent.
Okay, it's flat.
MAN: Come on, man!
MAN: It's not that easy.
DALLAS (off-screen): Relatively
dry and it's a small gap.
We've got this.
Yes, yes.
No.
MAN: Oh my goodness.
DALLAS (off-screen):
No, we haven't.
He made the jump but due
to his heavy backpack his
center of mass is, again,
behind his base of support
and so he falls backwards.
Grabbing the branch would
have been a good idea if it had
been attached to something.
This adventurer's not even
bothering, he's just wading,
unlike his friend
who's swimming.
It's only a small step but
the landing stone has been
lubricated by the
water so has a very low
coefficient of friction,
almost as low as his face.
DALLAS: Air is a remarkable
substance, not only does it
allow us to breathe,
which I think we can all agree is a good thing,
but if you compress it and
contain it you can have loads
of fun.
Like defying
the laws of physics
or for whacky furniture.
Whack, see.
The secret to understanding
and using compressed air is to
realize that all it wants to
do is stop being compressed air.
It wants to escape and in so
doing air teaches us valuable
science on
pressure differentials
and conservation of energy.
If air in one part of a
container is compressed it
will apply pressure to all
other parts until all areas
are the same pressure, this is
due to conservation of energy.
When a container of compressed
air is open to the atmosphere
the high pressure inside
equalizes with the lower
pressure outside, producing
a force as the air escapes
and whatever is containing
the compressed air needs to have
the material strength to
withstand the pressure
differential,
otherwise it will fail.
To sum up, pressure changes
will be transferred to all
parts of the container, give
something at high pressure an
opening and it will take
it and escape with force,
and finally whatever you do
make sure the container you're
using is strong enough.
So, now you know but
do our researchers know?
WOMAN: Don't break my bed!
DALLAS (off-screen):
Yes, they do.
The jumper has cleverly
demonstrated a basic
pneumatic system.
He adds kinetic energy
with his jump which causes a
pressure change in the bag and
due to conservation of energy
the kinetic energy is
transferred to her and she
then transfers that same
energy to the bedside table
via her head.
MAN: Are you OK?
DALLAS (off-screen):
How about something a little more high tech?
Surely these
amateur rocket engineers
understand pneumatics.
Ah, turns out they don't.
The young researcher was
trying to compress air by
jumping on the pump.
Unfortunately he misses.
WOMAN: Oliver!
DALLAS (off-screen):
But Oliver doesn't.
When the pump is pressed the
pressure differential created
applies a force that
launches the rocket.
WOMAN: Oliver!
DALLAS (off-screen): Good to get
a closer look at the physics.
Understanding the science
allows you to take advantage
of the science, like
building a beach trampoline.
Fun times.
MAN: Oh.
DALLAS (off-screen):
Yeah, less fun times.
The membrane of the beach
ball didn't have the material
strength to contain the higher
pressure produced by our more
short-footed researcher.
We can all use science
to elevate the ordinary.
A case in point, you could
just rollerblade or you could
use angular momentum to add
a little something extra and
make it a bit special.
You see. Special.
Now, what our young friend was
attempting was a rollerblade
flip and the reason he failed
was that he hadn't studied
angular momentum,
angular velocity or even
moment of inertia.
Luckily you can.
First he needs sufficient
take-off velocity for enough
height and air time
to perform the flip.
As he launches he leans to
generate angular momentum.
He then tucks in, decreasing
his moment of inertia,
which increases his
angular velocity,
meaning he spins faster
and completes his flip.
Angular momentum, the momentum
you have when you're spinning
cannot be changed
once you've launched.
Angular velocity, your spin
speed, can be changed mid-air,
as we've seen by
tucking in or decreasing
your moment of inertia.
Get all that right and you
can flip backwards or forwards.
Whether you want to or not.
(screams)
This skater wasn't trying to
add a flip but his one-foot
take-off gives him
unexpected angular momentum and
an unintentional
90-degree rotation.
MAN: Ow.
DALLAS (off-screen): Now,
this researcher is trying to
add a flip.
But he probably
wishes he hadn't.
He doesn't tuck in to reduce
his moment of inertia and so
doesn't have sufficient
angular velocity to complete
the turn but if he wanted
to smack his back on the floor.
It was textbook.
MAN: Oh.
DALLAS (off-screen): That's
better but that's worse.
Even though he had good speed
at take-off he holds his tuck
too long and so has too
much angular velocity.
He should have extended his
body earlier to increase his
moment of inertia
but instead he just extended
his dental work.
MAN: Oh.
DALLAS (off-screen): Okay,
good speed, great spin.
WOMAN: Yes.
DALLAS (off-screen):
Just the finish to go.
MAN: Yeah.
DALLAS (off-screen): Yeah, he
definitely meant to do that.
And that is it.
We have run out of time but
unfortunately not stupidity.
So, please do not copy any of
the dangerous stunts you have
just seen.
As Bill Nye the
Science Guy once said,
"Science is the best
idea humans have ever had."
Sorry Bill, I guess
this lot missed that class.
♪
♪
Captioned by
Cotter Captioning Services