[dramatic percussion music]
- HEY, THERE. WELCOME TO "NASA LAUNCHPAD."
I'M YOUR HOST, VINCE WHITFIELD.
CHECK THIS OUT.
TODAY WE'RE GOING TO BE TALKING ABOUT HOW THIS WORKS
AND SOME OTHER COOL STUFF BERNOULLI DID.
OH, THAT'S DANIEL BERNOULLI,
THE DUTCH-SWISS MATHEMATICIAN KNOWN FOR--
THAT'S RIGHT-- THE BERNOULLI PRINCIPLE.
REMEMBER BERNOULLI'S PRINCIPLE?
IF YOU DON'T, THAT'S OKAY.
LET'S CHECK IN WITH JAXA ASTRONAUT KOICHI WAKATA
AND ESA ASTRONAUT FRANK DEWINNE
ON BOARD THE INTERNATIONAL SPACE STATION
TO REVIEW THIS PRINCIPLE WITH US.
AND LET US SEE HOW BERNOULLI'S PRINCIPLE
CAN BE DEMONSTRATED FROM SPACE.
- IN A FLUID FLOW,
WHEN THE FLOW GETS HIGHER,
THE PRESSURE DECREASES.
AND THIS FACT IS NOW WELL-KNOWN AS THE BERNOULLI'S PRINCIPLE.
IF YOU APPLY THIS PRINCIPLE IN THE FLUID FLOW
IN A CLOSED SYSTEM SUCH AS WATER FLOW IN A TUBE,
IF YOU IMAGINE THE TUBE GETS BIGGER AND NARROWER,
THE PRESSURE ACTUALLY DECREASES
WHEN THE SPEED GETS HIGHER.
AND WHEN THE SPEED OF THE WATER GETS SLOWER,
THE PRESSURE ACTUALLY INCREASES.
ONE OF THE EXAMPLES THAT I CAN GIVE YOU IS THAT--
THINK ABOUT THE GARDEN HOSE.
AND IF WATER IS COMING OUT FROM THE GARDEN HOSE
WITH A MAXIMUM SPEED,
IF YOU STILL WANT TO INCREASE THE SPEED OF THE WATER
COMING OUT OF THE GARDEN HOSE,
WHAT YOU'RE GOING TO DO IS,
YOU'RE GOING TO PUT YOUR THUMB ONTO THE EXIT OF THE HOSE.
BY DOING THAT, THE SPEED OF THE WATER INCREASES,
AND AT THE SAME TIME,
THE PRESSURE OF THE WATER DECREASES.
- YOU HEARD KOICHI WAKATA TALK ABOUT WATER IN A GARDEN HOSE.
AND, YES, BERNOULLI'S PRINCIPLE DEALS WITH FLUID,
BUT HERE'S AN IMPORTANT THING TO KEEP IN MIND:
FLUID DOESN'T NECESSARILY MEAN LIQUID.
FLUID IS A GENERIC NAME THAT APPLIES TO SUBSTANCES
THAT BEHAVE IN CERTAIN WAYS.
FLUIDS FLOW SMOOTHLY AND AROUND THINGS.
SO GASES CAN BE FLUIDS, AS CAN PLASMA
AND EVEN, TO SOME EXTENT, PLASTIC SOLIDS.
LET'S TAKE A LOOK AT ANOTHER DEMONSTRATION
OF BERNOULLI'S PRINCIPLE,
THIS TIME SHOWING HOW IT CAN APPLY TO A GAS, LIKE AIR.
- WE ARE PLACING THESE CONTAINERS
NOT SO FAR FROM EACH OTHER, ABOUT FIVE TO TEN CENTIMETERS.
AND THEN KOICHI IS GOING TO BLOW
IN THE MIDDLE OF THOSE TWO CONTAINERS.
WHAT DO YOU EXPECT THAT WILL HAPPEN?
BECAUSE HE BLOWS IN THE MIDDLE,
THE CONTAINERS ARE GOING TO MOVE AWAY FROM EACH OTHER,
OR IF HE IS BLOWING IN THE MIDDLE,
THE CONTAINERS ARE GOING TO COME TOGETHER?
LET'S HAVE A LOOK.
WHAT YOU CAN VERY EASILY SEE HERE
IS, THE CONTAINERS ARE DRIFTING TOGETHER.
WHAT IS HAPPENING,
AGAIN, THE AIR THAT KOICHI IS BLOWING
THROUGH THE CONTAINERS
HAS HIGHER VELOCITY THAN THE SURROUNDING AIR.
BECAUSE OF THAT,
THE AIR TRAVELING IN BETWEEN THE CONTAINERS
HAS A LOWER PRESSURE
BECAUSE IT'S MOVING AT A HIGHER SPEED.
BECAUSE OF THAT, THE PRESSURE ON THE OUTSIDE
IS PRESSING THE TWO CONTAINERS TOGETHER.
YOU CAN ALSO OBSERVE THIS WHEN YOU'RE DRIVING ON A HIGHWAY
AND YOU GET TOO CLOSE TO A TRUCK, FOR EXAMPLE,
THAT IS DRIVING NEXT TO YOU.
AUTOMATICALLY YOU WILL BE DRAGGED TOWARDS THAT TRUCK,
AND YOU NEED TO STEER AWAY FROM THE TRUCK.
SO THIS IS ONE OF THE EXAMPLES AS WELL
OF THE BERNOULLI PRINCIPLE.
- GUESS WHAT.
YOU DON'T HAVE TO BE ON THE ISS
TO TRY THIS DEMONSTRATION.
OH, SURE, YOUR FOOD CONTAINERS WON'T STAY SUSPENDED
IN MIDAIR ON EARTH LIKE THEY DID ON THE ISS.
BUT TRY THIS DEMONSTRATION WITH TWO BALLOONS
HANGING CLOSE TO EACH OTHER.
THESE BALLOONS ARE HANGING FROM STRING TAPED TO A DOORWAY.
WHAT DO YOU THINK WILL HAPPEN WHEN YOU BLOW GENTLY
BETWEEN THE BALLOONS?
THAT'S RIGHT. THEY ARE PULLED TOGETHER.
THE AIR MOVING AIR BETWEEN THEM HAS LESS PRESSURE
THAN THE AIR ON THE OTHER SIDE OF EACH BALLOON,
SO THEY'RE PUSHED TOGETHER.
HERE'S ANOTHER EXAMPLE THAT WORKS ON EARTH AND IN SPACE.
WATCH FRANK'S DEMONSTRATION WITH A PIECE OF PAPER,
AND THEN TRY IT YOURSELF.
- RIGHT NOW, WHAT-- FRANK HAS A PIECE OF PAPER.
IT'S CURVED.
AND WHAT HE'S GOING TO DO IS,
NOW HE'S GOING TO HOLD THIS PAPER, AND IT'S CURVED,
AND HE'S GOING TO BLOW ON THE TOP SURFACE OF THE PAPER.
WHAT DO YOU THINK THIS PAPER WILL DO?
SINCE THE PAPER IS CURVED LIKE THIS,
DO YOU THINK THE PAPER WILL COME DOWN OR COMES UP?
LET'S SEE WHAT HAPPENS.
AS YOU SEE, WHEN FRANK BLOWS AIR ON THE TOP SIDE OF THE PAPER,
THE PAPER ITSELF LIFTS UP.
THIS IS AGAIN ONE EXAMPLE OF BERNOULLI'S PRINCIPLE.
THE AIR THAT GOES ON THE TOP SURFACE OF THE PAPER
HAS A HIGHER VELOCITY
THAN THE AIR THAT IS UNDERNEATH THE PAPER.
BECAUSE OF THE DIFFERENCE IN THE VELOCITY,
THE PRESSURE OF THE UPPER SURFACE HAS A SMALL NUMBER--
SMALL PRESSURE THAN THE LOWER SURFACE.
AS A RESULT, THE PAPER IS LIFTED UP.
- THIS IS A PRINCIPLE, OF COURSE,
THAT I HAVE USED A LOT IN MY PREVIOUS CAREER,
BECAUSE I USED TO BE A PILOT.
AND THIS IS HOW AIRPLANES FLY.
IF YOU LOOK TO THE WING OF AN AIRPLANE,
YOU SEE THAT IT'S CURVED,
ALWAYS A LITTLE BIT TOWARDS THE BOTTOM.
THE SIDE ON THE TOP SIDE IS LONGER
AND IS MORE CURVED THAN THE BOTTOM SIDE.
THIS MEANS THAT THE AIR TRAVELING
ON THE TOP OF THE WING
WILL TRAVEL FASTER THAN THE AIR UNDERNEATH THE WING,
CREATING A LOWER PRESSURE
AND LIFTING THE WING UP.
THIS IS WHAT WE CALL "LIFT,"
AND BECAUSE OF THIS LIFT, WE CAN TRAVEL
AND WE CAN FLY ALL AROUND THE WORLD.
NOT ONLY ME, BUT YOU AS WELL CAN TRAVEL WHEREVER YOU WANT
THANKS TO THE BERNOULLI EFFECT.
- SO THERE YOU GO.
WHEN YOU INCREASE THE SPEED IN A STREAM OF FLUID--
REMEMBER THAT'S BOTH LIQUIDS AND GASES--
THE PRESSURE OF THAT STREAM DECREASES.
PRETTY COOL, HUH?
BERNOULLI'S PRINCIPLE RELATES TO EVERYTHING,
FROM SPRAYING YOUR BEST FRIEND WITH THE HOSE
TO FLYING IN AN AIRPLANE.
THERE'S ACTUALLY MORE THAN BERNOULLI'S PRINCIPLE INVOLVED
WHEN YOU TAKE OFF IN AN AIRPLANE.
BUT THAT'S ANOTHER TOPIC FOR ANOTHER "NASA LAUNCHPAD."
WELL, THAT'S IT FOR NOW.
SPECIAL THANKS TO OUR ON-ORBIT ASTRONAUTS.
UNTIL NEXT TIME, I'M VINCE WHITFIELD.
THANKS FOR WATCHING "NASA LAUNCHPAD."