03x08 - Speed

[bunniefuu]

This week on DFTV, we're training on the

sore track. Kids are speed skating some

wicked turns. We and Mass Gators are the

best way to enter a speed skate

turn. Goals 21 go and boarding down

gnarly mountain trails. Check this out.

This is a mountain board. Which tire

pressure will give us the most speed and

control?Major funding for Dragonfly

TV is provided by the Best Buy Children's

Foundation. We're excited to see kids

like you exploring the world of science

and technology, because what you're

learning is going to change the way we

live. Best by the future looks fun.

And by the National Science Foundation,

supporting education and research in

science, mathematics and technology.

The National Science Foundation,

America's investment in the future.

Dragonfly TV. Dragonfly

TV.

Hey, guys, what's up?This is DFTV. This

week we've got some kids who love to go

fast. Racing, zooming, speeding, flying,

cruising. But let's slow down for the

details. This right here is a mountain

board. It's a type of skateboard, but way

cooler because it's for dirt trails. The

steeper, the better. Emil, Sean, and Ben,

check out the difference between squishy

and firm tires. First, it's speed skating

with Sarah, Eric, Lisa, and Ned. We're

looking for speed and trying not to wipe

out on some wicked turns. Ned even takes

a hit for science. Watch this. Ready,set.

Sarah's really energetic, kind of like

kooky. As a skater, Sarah is

really good. She figure skates as well,

so then I think that would be really

hard. She always has 100% energy,

and always seems like she has way too

much caffeine. Sorry, do I know you?

Lisa's a really, really strong person and

she has a lot of power off every stroke.

She likes to do long distance skating

like I do. When Lisa and Sarah get

together, it always triples in noise

level. What are you some kind of a nut?

Eric is a really dedicated person. He

works really hard and never gives up.

He's just just always doing 110%. His

mom and like all of her sisters and stuff

are skaters and they were all really

good. Very impressive. Thank you. That's

a great skater. He always does. good and

if he doesn't do good it's not a big

deal. He'll just try harder next time.

He's a good person to have on your team

because he'll support you and give you

encouragement. He seems like he's really

smart. Sometimes I can't really

understand him because he's like smart

talk. Can you dig it?

The fastest speed skaters in the world

can go almost 40 miles an hour. But

everything depends on what kind of race

you're talking about. There's short track,

And there's long track. We just happened

to do both. Long track's big. It's about



against the clock with one other person.

Short track happens on an oval, 111

meters long. That's about the size of a

hockey rink. You skate in the pack with

four or six other people. We're

training on the short track.

You're trying to win a short track race.

Winning or losing comes down to fractions

of a second. We always want to skate full

out going into a turn so we get maximum

speed. We're

guessing that how you start the turn is

really key. Do you want to start the turn

tight, medium, or wide?

We're going to test things out to see

which one helps us keep up our speed.

Gotcha. We talked about which type of

turn would give us the most speed and

control. Well, I think if you go on the

inner track, you'll have a much faster

time than if you go on the outer track.

Well, that's true, but when you're going

around the inner track, you're always

gonna swing out and lose control. I think

if you went in the middle, then you

wouldn't lose control as much. It'd be

about the same time. Yeah, I'd rather go

for the faster time and less control.

Yeah, I think the outer, you lose so much

time, that the inner or the middle one

would be the best. We'll start tight,

medium, and wide.

We'll clock the time it takes to go

through the turn with a stopwatch. We'll

report how in control our bodies felt

during the turn, and give ourselves a

bronze, silver, or gold medal for

control. And then we'll report our path

on the corner candle. We'll do three

trials for each. We'll get one lap to

build our speed before we time the turn.

Here we go now.

What was that?Silver. Silver?It's

definitely a bronze.

How does the control feel?I'm getting

arch-tight. And then Tosanna likeyou know

I would get a branch.

Early on in the test, I tripped on the

stopwatch that was in my pocket. It fell

out. Fell pretty hard, sprained my ankle.

I get a tinfoil medal for that one. Thank

you, Eric.

So for the rest of the test, I'll just

help with the data.

See some really fast stuff, Eric.

That was probably the silver. I didn't

mess up, but I didn't go fast enough.

What was that, bronze, silver, or gold?I

give that a silver.

When I'm speed skating, I feel more

relaxed, and I don't really pay attention

to what's going on around me because I'm

in like my own little world. I love speed

skating because of all the friends you

make, and it's just a fun time to have.

The verdict is... Bronze. Whoo!

Gold.

Sara, how was it, Eric?

I think that was gold. All right. Yeah!

Gold. Whoo. Go, gold. It's

bronze, silver, gold.

Check this. The guys told me it was 10

below 0 when they did their test. Are you

serious?Dead serious. Oh, you'd never

catch me out there. But ice skating keeps

you warm, Michael. Or you could just wear

a hat. Cute.

That's her fashion cheap. You guys should

know that Eric's first version of this

investigation was actually a science

surprise, which is how we found out about

him. So people, remember,

send us your science fair investigations

and you may land on our show. But before

you do that, it's time for today'sriddle.

See if you can figure this one out. How

can you get your bike to go 80 miles an

hour?With no

brooms, rocket fuel, or motors, just your

feet on the pedals. Crazy, right?A bike

that can go faster than the speed limit

just by pedaling. So to help you out, Dar

and Dylan are rolling out their wheels.

I think to go faster, you need to pedal

harder. Funny, Dylan, but let's use my

bike. You know you can't just be pedaling

or anyone can go 80 miles per hour.

I bet it has something to do with the

gears. Let's try different gear

combinations. Yeah, that's a good idea.

Trial number one.

I don't think that's fast enough. Trial

number two.

You're getting there. Trial number

three.

He went the fastest with the largest

front gear and the smallest back gear.

But we were still way below 80 miles an

hour. I think we need a gigantic front

gear. Or more muscle?Show it if you both

ride. Sure. I

guess more muscle doesn't make it work

either. If it's not the pedaling, it's

not the gears, and it doesn't matter how

strong you are. What's left?

So those two are pinning their hopes on

the gears, but the 80 mile an hour secret

remains a mystery. That's why it's a

riddle. OK, guys, what else could help

you go that fast?Go ahead and try a

guess. And we'll bring you the answer at

the end of the show. But now it's back to

our speed skaters. We're probably warm

and toasty by the fire, cooking up their

results.

Hey, guys, it's cold out here. Let's go

inside.

After watching the videotape of our test,

we made a chart showing the average time

and control for each of our turns.

Okay, let's check out what our average

control was. On my tight turn, it seemed

like I had no control, and on my wide

turn, it seemed like I had a lot more

control. When I made the tight turn, I

ended up wide anyway because I lost

control. Maybe that's why your time was

slower than the middle turn. Yeah, that

could be. I felt like I had more control

on the wide turn, too. For mine, it was

the opposite. I felt way more control on

the tight turn than on the outer turns. I

felt like, ooh, la-la land or something.

Why did they have less control on the

outside when everybody else was opposite

of that?Because I'm

special. Maybe you just got the metals

confused. All

right, break it up. Let's move on to

times. My times just got slower the wider

the turn was. Mine are really

slow compared to your guys'. Maybe I

got faster on my medium turn because I

got more warmed up when I did the medium

turn than when I did the tight turn. On

the tighter turn, it seemed like my

skates had to push harder in order to

hold the turn. Yeah, I guess our skates

really have to get a good push off the

ice to make a tight turn. Seemed like

when we skated the outer turn, then we

didn't have to push that hard on the ice.

And that meant our skates were less

likely to slip out. We could have better

control. So whether we take the wide turn

or the tight turn, there's always a

trade-off between time and control.

Ohh The skaters rocket off the

start. It looks like Lisa's in the head,

but the sled with Ned is pulling ahead.

All right.

So now we know what a difference a good

turn can make, but what about the skate

itself?Well, until just a few years ago,

all speed skaters used fixed blades. But

now most skaters use clap skates to get

more power out of each stride. They have

a spring-loaded hinge at the toe, which

allows the skater's heel to come up and

the blade to stay in contact with the

ice. It's so smart. You know,

some skaters think that these new-fangled

skates add an unfair mechanical

advantage. But actually, if everyone's

wearing the same skate, it just comes

down to muscle power and strategy. You're

right. But now we're off to break records

at the State Fair. Hi, I'm

Eliza. I'm Mary Jane. Great plates and

win teddy bears. We're assigned to win

carnival games. There goes another teddy

bears. If we made it on Dragonfly TV, you

can too. Here's how.

Surf on over to the DFTV website. It's at

PBS Online at pbskids.org.

Once you're there, click on Dragonfly TV

and tell us whatquestions you're

investigating and what you found out. You

might find yourself from Dragonfly TV.

What was the first man-made invention to

break the sound barrier?Rocket,

blender, whip.

Whip. Let's

go!

I'm Ryan Newman, and I'm a professional

race car driver.

This is our shop. You could call it our

laboratory.

Basically, we use engineering to win.

We use these tires to make our car grip

at 200 miles an hour.

I started driving cars when I was 4 1/2.

My parents got me involved in quarter

midgets and quarter midgets just like a

go car with a roll cage. We only race in

ovals. I was a two time national

champion, was always good in math and

physics.

I went to school as an engineer, wanted

to be a mechanical engineer and ended up

being a vehicle structure engineer at

Purdue University. Things you learn in

college as far as time management and for

me it was problem solving with the

engineering background, trying to get to

the solution the fastest and easiest way

with you knowat the same time, getting

the right answer.

Racing is one big huge equation, and

there's so many variables, whether it's

blowing a tire or having a good engine or

having a good downforce, things like that

that make a difference. And just one of

those variables can just totally b*mb the

equation. That's right.

Physical forces that I feel, be it

lateral or vertical forces, sometimes can

be almost nothing and sometimes can be

really huge. I think maybe a roller

coaster is one of the best examples

because of the change of direction, the

speed, you know, the up and down. The

roller coaster comes in, you can feel the

bank, you can feel the load, you can feel

it in the seat of your pants.

I like what I do. It's definitely a lot

of fun. I don't consider it a job. I feel

like I get paid to perform and I just go

out and do the best job that I can. And

as a race car driver, it's fun.

Have you ever wondered how a race car

going 200 miles an hour can take a turn

without flying off the track?Well, race

cars are designed aerodynamically to make

use of downforce. Downforce is the same

as the lift used by airplanes wings. Only

it acts to press down instead of lifting

up. And some race cars have inverted

wings to increase traction and force them

down so that they won't fly off the

track. But now it's time for an

aerodynamic celebrity. So let's hear it

from Olympic gold medalist in skating,

Kristy Yamaguchi. Who's spinning science

fact out of science fiction.

Guess which one of these dinosaurs was

the biggest threat to humans?The

Stegosaurus, the Tyrannosaurus

Rex, or the

Triceratops?The answer is

none of them.

The first humans didn't have to worry

about dinosaurs because they didn't live

at the same time. To see just how far

apart humans and dinosaurs live, let's

use this calendar. The first primitive

life forms appeared on January 1st.

More and more life evolved, but where are

the dinosaurs?They don't show up until

August 4th, and the dinosaurs

lasted until November 19th, when they

went extinct. So what about humans?

It's not until late on December 31st that

the first humans arrived.

So that means humans missing a dinosaur

by over 60 million years. So

dinosaurs definitely weren't enjoying

people snacks.

This is Kristy Yamaguchi helping to turn

science fiction into science fact. For

Dragonfly TV.

So I've been having T-Rex nightmares for

no reason at all. Yeah, I think you've

just seen too many movies with ferocious,

hungry little girl eating dinosaurs in

them. What are you doing?My dinosaur

impression. Yeah, OK, so now for three

guys who can outrun any dinosaur on this.

Hi, I'm Sean. I'm Neil. And I'm

Ben. This is a mountain board.

Basically, mountain boarding is

snowboarding on dirt. And if you haven't

seen it before, check this out. A

mountain board is a kind of skateboard on

steroids. The decks are big and beefy,

the wheels are made of rubber, and your

feet fit in these bindings.

There are many different ways to mount on

board, like big air, where riders go off

jumps and try to get the most air they

can and do their biggest trick.

Every ride where we hit single track,

fire roads, and more natural mountainous

terrain.

And border cross, where riders race

head-to-head down a dirt track.

We've been riding in the mountains of

Southern California for about a year now.

We've noticed that how much air we put in

our tires seems to make a big difference

in the ride. If the pressure's not right,

you can even lose control.

What we're trying to find out is which

tire pressure will give us the most speed

and control. We had to find a track where

we could set up some obstacles and see

how the tires performed. I like this

track with a steep run up and then a nice

level path for carving left or right.

Well, Neil wanted to use this steep hill.

I say let's just start right here and to

see how far we can make it. Let's just

put. Cone right here.

Cone right here. Cone right here. Cone

right here. One thing is, we're going to

get going really fast on this. What do

you think, man?I think we should use the

other course because our tires are in

contact with the ground the whole time.

With this course, you're hopping up and

down, so the heights of the hop and the

angle that you're turning with that is

just it's going to be different every

time. Well, let's go down to the other

track and set that one up. We put down

a series of cones to mark our course. So

you're going to. on this side of the

cone. Yeah. We'll ride the course at

three different tire pressures: 10 psi,



PSI means pounds per square inch, the

measurement of how much air is in your

tire. More psi means your tire is harder,

and less psi means your tire is

squishier. We'll run this course three

times with each tire pressure. 10 psi is

pretty soft, 25 psi is close to

normal, and 60 is just rock hard. We'll

rate each run fromTo five. Yeah. One

being the worst control, five being the

best control. Yeah. And we'll time it and

see how fast we run the course and see

which tire pressure works the best. All

right, let's get. Sounds good. Our first

test will be the lowest tire pressure of

the day, 10 PSI. What do you think's

gonna happen with the low tire pressure?I

think with the low tire pressure, you'll

probably make it more smooth, but it'll

probably be harder to turn. And then at

the end, you'll probably be going slower,

and you won't really be able to hit the

jump. I think with the high pressure,

we're going to be going really fast, but

we're going to use a lot of checking off

our speed, and it'll be a lot sketchier.

But we might make it for the course

faster. We'll just have to see what

happens.

OK, Neil, you ready?Yeah. OK.

Three, two, one, go.



that your control was?

Rating control?It was good.

So between one and five. Probably a five

for control. Yeah. We'll take one more

run and see how it goes. All right. You

guys ready?OK, let's go. We each took

three runs at 10 PSI, and together

averaged at 17.1 seconds per run,

with an average control rating of four.

That's on a scale of one to five, five

being the best. This is kind of slow, not

that fast, kind of, you're

losing a lot of speed for the turns.

Let's move on to 25. Okay, man, let's go.

When I think we go up to 25, I think it's

gonna be a lot faster. Three, two,

one, go.

So again, we averaged our times to

compare with our 10 PSI runs. 25

PSI was definitely faster at 14.0

seconds, but our control ratings dropped

just a little to 3.8.

Finally, we moved on to the maximum tire

pressure, 60 PSI. With 60

PSI, we had so much speed off that first

hill.

That we found it hard to carve good

turns, and at this tire pressure,

control was definitely a challenge. We

averaged our times and were a little

surprised to find that 60 PS I was not

the fastest, and it also came in with the

lowest control ratings. With our tests

complete, we combined all of our

averages, made a chart, and took a break

to figure it all out. At 10

PS I we had the slowest time, but the

highest board control rating. 25 and 60

were definitely faster, but 60 had the

lowest rating for board control. So what

do you think the difference was?Well, the

difference was a matter of how much of

the tire is touching the ground. When you

have more of the tire touching the

ground, it causes more friction and that

makes you slower, but it can give you

more control. But with less of the tire

touching the ground, such as 60 PS I,

you have more speed but probably less

control. So Ben, what do you think the

best PSI is?Well, it depends on the

course and your ability, right?Like on a

fast course such as asphalt, you're

probably going to want to go with 10 PSI

because it might give you the most

control. Yeah, but on a slower course

such as deep sand, you want less tire in

contact with the ground to keep your

speed up. And ultimately it really has to

do with how good the rider is. A better

rider can handle the faster speed and

less control of 60 PSI. Well, a

beginner might want to stay with 10 or



and challenging, so we're going to crank

it up to 60 PSI and hit the hills one

last time.

OK, I still don't get why anyone wants

squishy tires. I mean, who wants

half-inflated wheels when they're biking?

Well, Marco, under-inflating can be used

to give more control, like when you're

doing stunts. In fact, Brian is here to

demonstrate. Hey, what works best when

you're hopping, Brian?Tire pressure. Low

tire pressure?Sweet. Or

when he's zipping around, higher tire

pressure means less friction and more

speed. Wait, is it true that you, like,

unicycled on a mountain?Yeah. That's so

cool. And now for more elaborate hopping

demonstrations. Ready?One.

Two. One more. Uh

Marico, you're next. No.

Hey, maybe tire pressure has something to

do with today's riddle. Or maybe not. So

have you figured out how to make a bike

go 80 miles an hour?

Out here we reach speeds on our bikes of

more than 80 miles an hour. That's the

speed that most cars go on the freeway.

We train hard, but it's not just our

muscles at work. These bikes are built

for one thing. speed. The

key is cutting down on wind resistance.

Instead of an upright position, we use a

reclined position. The rider presents

much less surface area to the wind,

decreasing the drag. Second, we cover the

bike in a smooth profile. This allows the

wind to move around the bike instead of

pushing against it. My bike is so

aerodynamic, it's eight times more

efficient than a regular bicycle.

Okay, you think that was cool?What about

human-powered flight?In 1977, the

GossamCondor, the first human-powered

aircraft, flew just over a mile on pedal

power alone. Here's a scale version. On

the original, it had a 96-foot wingspan

and weighed less than 70 pounds. And if

you'd like to see the original, it's

being displayed at the National Air and

Space Museum in Washington, DC. How do

you propose I get there, Michael?A fly.

Let's move on to your ideas and

inventions. And make sure to tell us all

about them, because, well, if you don't.

Who will?Here's how. To find out more

about Dragonfly TV, head to PBS Online at

PBS. Kids.org or write us at

Dragonfly TV 172 E 4th St. St.

Paul, MN 55101.

What's the record for the fastest land

speed in a car?335 miles per

hour, 638 miles per hour,





See what's coming up this season on

Dragonfly TV. So that's one. That's a

really big one. One. We explore how germs

are spread. Or not. That's freaky.

That's scary. Can dogs actually see

color, just like people?Go get it. Coming

up soon on Dragonfly TV...

Well, that wouldn't butt fast. That's

what happens when you do a show about

speed. So stay tuned for our show about

slow motion. Who knows what will happen

then?See you soon on

DFTV. Major

funding for Dragonfly TV is provided by

the Best Buy Children's Foundation. We're

excited to see kids like you exploring

the world of science and technology,

because what you're learning is going to

change the way we live. Best Buy, the

future looks fun.

And by the National Science Foundation,

supporting education and research in

science, mathematics and technology.

The National Science Foundation,

America's investment in the future.