WEBVTT

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[dramatic percussion music]

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- HEY, THERE.
WELCOME TO "NASA LAUNCHPAD."

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I'M YOUR HOST,
VINCE WHITFIELD.

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CHECK THIS OUT.

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TODAY WE'RE GOING TO BE TALKING
ABOUT HOW THIS WORKS

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AND SOME OTHER COOL STUFF
BERNOULLI DID.

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OH, THAT'S DANIEL BERNOULLI,

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THE DUTCH-SWISS MATHEMATICIAN
KNOWN FOR--

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THAT'S RIGHT--
THE BERNOULLI PRINCIPLE.

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REMEMBER BERNOULLI'S PRINCIPLE?

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IF YOU DON'T, THAT'S OKAY.

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LET'S CHECK IN WITH
JAXA ASTRONAUT KOICHI WAKATA

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AND ESA ASTRONAUT
FRANK DEWINNE

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ON BOARD THE INTERNATIONAL
SPACE STATION

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TO REVIEW THIS PRINCIPLE
WITH US.

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AND LET US SEE
HOW BERNOULLI'S PRINCIPLE

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CAN BE DEMONSTRATED FROM SPACE.

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- IN A FLUID FLOW,

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WHEN THE FLOW GETS HIGHER,

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THE PRESSURE DECREASES.

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AND THIS FACT IS NOW WELL-KNOWN
AS THE BERNOULLI'S PRINCIPLE.

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IF YOU APPLY THIS PRINCIPLE
IN THE FLUID FLOW

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IN A CLOSED SYSTEM
SUCH AS WATER FLOW IN A TUBE,

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IF YOU IMAGINE THE TUBE
GETS BIGGER AND NARROWER,

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THE PRESSURE
ACTUALLY DECREASES

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WHEN THE SPEED GETS HIGHER.

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AND WHEN THE SPEED OF THE WATER
GETS SLOWER,

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THE PRESSURE
ACTUALLY INCREASES.

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ONE OF THE EXAMPLES THAT I CAN
GIVE YOU IS THAT--

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THINK ABOUT THE GARDEN HOSE.

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AND IF WATER IS COMING OUT
FROM THE GARDEN HOSE

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WITH A MAXIMUM SPEED,

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IF YOU STILL WANT TO INCREASE
THE SPEED OF THE WATER

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COMING OUT OF THE GARDEN HOSE,

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WHAT YOU'RE GOING TO DO IS,

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YOU'RE GOING TO PUT YOUR THUMB
ONTO THE EXIT OF THE HOSE.

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BY DOING THAT, THE SPEED
OF THE WATER INCREASES,

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AND AT THE SAME TIME,

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THE PRESSURE OF THE WATER
DECREASES.

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- YOU HEARD KOICHI WAKATA TALK
ABOUT WATER IN A GARDEN HOSE.

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AND, YES, BERNOULLI'S PRINCIPLE
DEALS WITH FLUID,

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BUT HERE'S AN IMPORTANT THING
TO KEEP IN MIND:

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FLUID DOESN'T NECESSARILY
MEAN LIQUID.

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FLUID IS A GENERIC NAME
THAT APPLIES TO SUBSTANCES

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THAT BEHAVE IN CERTAIN WAYS.

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FLUIDS FLOW SMOOTHLY
AND AROUND THINGS.

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SO GASES CAN BE FLUIDS,
AS CAN PLASMA

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AND EVEN, TO SOME EXTENT,
PLASTIC SOLIDS.

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LET'S TAKE A LOOK
AT ANOTHER DEMONSTRATION

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OF BERNOULLI'S PRINCIPLE,

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THIS TIME SHOWING HOW IT CAN
APPLY TO A GAS, LIKE AIR.

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- WE ARE PLACING
THESE CONTAINERS

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NOT SO FAR FROM EACH OTHER,
ABOUT FIVE TO TEN CENTIMETERS.

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AND THEN KOICHI
IS GOING TO BLOW

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IN THE MIDDLE
OF THOSE TWO CONTAINERS.

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WHAT DO YOU EXPECT
THAT WILL HAPPEN?

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BECAUSE HE BLOWS
IN THE MIDDLE,

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THE CONTAINERS ARE GOING TO MOVE
AWAY FROM EACH OTHER,

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OR IF HE IS BLOWING
IN THE MIDDLE,

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THE CONTAINERS ARE GOING
TO COME TOGETHER?

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LET'S HAVE A LOOK.

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WHAT YOU CAN
VERY EASILY SEE HERE

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IS, THE CONTAINERS
ARE DRIFTING TOGETHER.

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WHAT IS HAPPENING,

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AGAIN, THE AIR
THAT KOICHI IS BLOWING

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THROUGH THE CONTAINERS

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HAS HIGHER VELOCITY
THAN THE SURROUNDING AIR.

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BECAUSE OF THAT,

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THE AIR TRAVELING
IN BETWEEN THE CONTAINERS

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HAS A LOWER PRESSURE

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BECAUSE IT'S MOVING
AT A HIGHER SPEED.

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BECAUSE OF THAT,
THE PRESSURE ON THE OUTSIDE

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IS PRESSING THE TWO CONTAINERS
TOGETHER.

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YOU CAN ALSO OBSERVE THIS
WHEN YOU'RE DRIVING ON A HIGHWAY

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AND YOU GET TOO CLOSE
TO A TRUCK, FOR EXAMPLE,

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THAT IS DRIVING NEXT TO YOU.

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AUTOMATICALLY YOU WILL BE
DRAGGED TOWARDS THAT TRUCK,

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AND YOU NEED TO STEER AWAY
FROM THE TRUCK.

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SO THIS IS ONE OF THE EXAMPLES
AS WELL

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OF THE BERNOULLI PRINCIPLE.

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- GUESS WHAT.

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YOU DON'T HAVE TO BE
ON THE ISS

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TO TRY THIS DEMONSTRATION.

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OH, SURE, YOUR FOOD CONTAINERS
WON'T STAY SUSPENDED

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IN MIDAIR ON EARTH
LIKE THEY DID ON THE ISS.

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BUT TRY THIS DEMONSTRATION
WITH TWO BALLOONS

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HANGING CLOSE TO EACH OTHER.

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THESE BALLOONS ARE HANGING
FROM STRING TAPED TO A DOORWAY.

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WHAT DO YOU THINK WILL HAPPEN
WHEN YOU BLOW GENTLY

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BETWEEN THE BALLOONS?

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THAT'S RIGHT.
THEY ARE PULLED TOGETHER.

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THE AIR MOVING AIR BETWEEN THEM
HAS LESS PRESSURE

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THAN THE AIR ON THE OTHER SIDE
OF EACH BALLOON,

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SO THEY'RE PUSHED TOGETHER.

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HERE'S ANOTHER EXAMPLE THAT
WORKS ON EARTH AND IN SPACE.

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WATCH FRANK'S DEMONSTRATION
WITH A PIECE OF PAPER,

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AND THEN TRY IT YOURSELF.

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- RIGHT NOW, WHAT--
FRANK HAS A PIECE OF PAPER.

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IT'S CURVED.

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AND WHAT HE'S GOING TO DO IS,

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NOW HE'S GOING TO HOLD
THIS PAPER, AND IT'S CURVED,

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AND HE'S GOING TO BLOW
ON THE TOP SURFACE OF THE PAPER.

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WHAT DO YOU THINK THIS PAPER
WILL DO?

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SINCE THE PAPER IS CURVED
LIKE THIS,

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DO YOU THINK THE PAPER
WILL COME DOWN OR COMES UP?

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LET'S SEE WHAT HAPPENS.

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AS YOU SEE, WHEN FRANK BLOWS AIR
ON THE TOP SIDE OF THE PAPER,

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THE PAPER ITSELF LIFTS UP.

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THIS IS AGAIN ONE EXAMPLE
OF BERNOULLI'S PRINCIPLE.

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THE AIR THAT GOES
ON THE TOP SURFACE OF THE PAPER

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HAS A HIGHER VELOCITY

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THAN THE AIR
THAT IS UNDERNEATH THE PAPER.

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BECAUSE OF THE DIFFERENCE
IN THE VELOCITY,

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THE PRESSURE OF THE UPPER
SURFACE HAS A SMALL NUMBER--

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SMALL PRESSURE
THAN THE LOWER SURFACE.

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AS A RESULT,
THE PAPER IS LIFTED UP.

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- THIS IS A PRINCIPLE,
OF COURSE,

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THAT I HAVE USED A LOT
IN MY PREVIOUS CAREER,

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BECAUSE I USED TO BE A PILOT.

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AND THIS IS HOW AIRPLANES FLY.

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IF YOU LOOK TO THE WING
OF AN AIRPLANE,

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YOU SEE THAT IT'S CURVED,

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ALWAYS A LITTLE BIT
TOWARDS THE BOTTOM.

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THE SIDE ON THE TOP SIDE
IS LONGER

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AND IS MORE CURVED
THAN THE BOTTOM SIDE.

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THIS MEANS
THAT THE AIR TRAVELING

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ON THE TOP OF THE WING

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WILL TRAVEL FASTER THAN THE AIR
UNDERNEATH THE WING,

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CREATING A LOWER PRESSURE

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AND LIFTING THE WING UP.

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THIS IS WHAT WE CALL "LIFT,"

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AND BECAUSE OF THIS LIFT,
WE CAN TRAVEL

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AND WE CAN FLY ALL AROUND
THE WORLD.

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NOT ONLY ME, BUT YOU AS WELL
CAN TRAVEL WHEREVER YOU WANT

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THANKS TO THE BERNOULLI EFFECT.

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- SO THERE YOU GO.

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WHEN YOU INCREASE THE SPEED
IN A STREAM OF FLUID--

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REMEMBER THAT'S BOTH LIQUIDS
AND GASES--

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THE PRESSURE
OF THAT STREAM DECREASES.

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PRETTY COOL, HUH?

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BERNOULLI'S PRINCIPLE
RELATES TO EVERYTHING,

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FROM SPRAYING YOUR BEST FRIEND
WITH THE HOSE

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TO FLYING IN AN AIRPLANE.

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THERE'S ACTUALLY MORE THAN
BERNOULLI'S PRINCIPLE INVOLVED

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WHEN YOU TAKE OFF
IN AN AIRPLANE.

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BUT THAT'S ANOTHER TOPIC
FOR ANOTHER "NASA LAUNCHPAD."

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WELL, THAT'S IT FOR NOW.

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SPECIAL THANKS
TO OUR ON-ORBIT ASTRONAUTS.

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UNTIL NEXT TIME,
I'M VINCE WHITFIELD.

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THANKS FOR WATCHING
"NASA LAUNCHPAD."