Transcript for:
Understanding Air Pressure in Flight

Bill: <i> THIS IS THE SKY.</i> <i> I KNOW WHAT YOU'RE SAYING.</i> <i> YOU'RE SAYING,</i> <i> "THERE'S NOTHING THERE."</i> <i> WHAT DO YOU MEAN</i> <i> THERE'S NOTHING THERE?</i> <i> THERE'S ENOUGH TO FLY ON.</i> <i> WANT TO SEE IT AGAIN?</i> THINGS FLY. PRETTY COOL, HUH? Captioning made possible by NATIONAL SCIENCE FOUNDATION ♪ BILL NYE THE SCIENCE GUY ♪ ♪ BILL NYE THE SCIENCE GUY ♪ ♪ BILL, BILL, BILL, BILL, BILL, BILL ♪ ♪ BILL NYE THE SCIENCE GUY ♪ Woman: <i> SCIENCE RULES.</i> ♪ BILL NYE THE SCIENCE GUY ♪ <i>INERTIA IS A PROPERTY OF MATTER.</i> ♪ BILL, BILL, BILL, BILL ♪ ♪ BILL NYE THE SCIENCE GUY ♪ ♪ BILL, BILL, BILL, BILL ♪ <i> "T" MINUS SEVEN SECONDS.</i> ♪ BILL NYE THE SCIENCE GUY. ♪ Announcer: BILL NYE THE SCIENCE GUY, <i> BROUGHT TO YOU BY...</i> <i> WITHOUT AIR, YOU AIN'T FLYING.</i> AIR PRESSURE MAKES THINGS FLY. THAT'S IT. FROM JUNE BUGS TO GIANT JETS THEY ALL FLY BECAUSE OF AIR PRESSURE. YOU'RE SAYING, "HOW CAN AIR MAKE THAT MUCH PRESSURE? "IT'S NOT LIKE IT HAS A TEST TOMORROW OR ANYTHING. AND BESIDES, AIR IS SO LIGHT AND, WELL, AIRY." BUT IT'S AIR PRESSURE THAT LETS US BREATHE. AND IT'S AIR PRESSURE THAT MAKES THE WIND BLOW. WITHOUT AIR PRESSURE, NOTHING COULD FLY. TAKE A LOOK AT THIS. IT'S OUR PLASTIC AIRPLANE OF SCIENCE. THIS AIRPLANE IS FLYING EVEN THOUGH IT MAY NOT BE GOING ANYWHERE. MAYBE YOU KNOW THE FEELING. AIR MOVING OVER THE WINGS IS CREATING WHAT SCIENTISTS CALL... MAYBE A SCIENTIST LIKE YOU CALLS "LIFT." IT'S LIKE WHEN YOU LIFT SOMETHING UP LIKE MAYBE YOU LIFT UP A 400-TON JUMBO JET OR A PLASTIC AIRPLANE OF SCIENCE. WHERE DOES THE LIFT COME FROM? IT COMES FROM MOVING AIR. WHEN THE WINGS ARE TIPPED UP A LITTLE BIT THE MOVING AIR CREATES DIFFERENCES IN AIR PRESSURE. THE AIR GOING UNDERNEATH THE WINGS IS GOING A LITTLE MORE SLOWLY THAN THE AIR GOING OVER THE TOP. WHEN AIR IS MOVING THIS WAY, IT PUSHES THIS WAY. IT DOESN'T PUSH SO MUCH UP OR DOWN. SO THERE'S A LITTLE HIGHER PRESSURE UNDER THE WING THAN ON TOP. THAT DIFFERENCE IN AIR PRESSURE CREATES LIFT. THIS THING THAT HAPPENS WITH AIR THAT WHEN IT'S MOVING THIS WAY IT PUSHES THIS WAY AND NOT SO MUCH SIDEWAYS <i> IS NAMED AFTER A SWISS GUY</i> <i> NAMED BERNOULLI.</i> SO, WE CALL IT "THE BERNOULLI EFFECT." WHEN THE WING'S CURVED ON TOP IT DOESN'T NEED TO BE TIPPED UP AS MUCH TO GET LIFT. IT DOESN'T NEED AS BIG OF AN ANGLE OF ATTACK. AIRPLANES FLY BECAUSE THEIR WINGS DEVELOP DIFFERENCES IN AIR PRESSURE WHEN THEY'RE CURVED ON TOP OR GIVEN AN ANGLE OF ATTACK. SO, AIRPLANES ARE HELD UP BY SOMETHING WE CAN'T SEE: INVISIBLE AIR PRESSURE. HUH? NOT THAT BAD. NOT THAT BAD. WHEN WE THROW THE PLASTIC AIRPLANE OF SCIENCE DIFFERENCES IN AIR PRESSURE CREATED ON THE WING DEVELOP LIFT. HUH? LIFT IS WHAT MAKE FLYING DISKS FLY. AND KITES. CHECK THIS OUT. ORDINARY BALLOON. SOME OF THE AIR WE BREATHE IS NOW INSIDE THE BALLOON. I'VE USED THE POWER OF MY LUNGS TO FORCE MOLECULES INTO THE BALLOON. THE MORE MOLECULES IN THE BALLOON BOUNCING AROUND THE GREATER THE PRESSURE AND THAT PRESSURE CAUSES THE BALLOON TO EXPAND. AIR PRESSURE. GODZILLA. DAISIES. THIS ONE? WELL, WE'RE GOING TO HAVE TO WORK ON THAT. AIR PRESSURE GIVES THESE BALLOONS THEIR SHAPE. WITHOUT AIR PRESSURE, WE'D HAVE SOMETHING LIKE THIS... ALTHOUGH WATCHING BALLOONS FLY AROUND, NOT THAT BAD. HERE'S ANOTHER EXPERIMENT YOU CAN DO THAT SHOWS WHAT AIR PRESSURE CAN DO. GET TWO PENCILS AND A NICE, BIG BALLOON. NOW GET A HEAVY BOOK. THE BALLOON CAN LIFT THE BOOK. YOU CAN DO IT WITH AIR PRESSURE. SET TWO PENCILS ON A TABLE. PLACE THE BALLOON BETWEEN THE PENCILS WITH THE OPEN END OF THE BALLOON HANGING OVER THE EDGE. NOW PUT THE BOOK ON THE PENCILS. JUST BLOW INTO THE BALLOON. YOU'RE LIFTING THE BOOK WITH AIR PRESSURE FROM YOUR BREATH. PHEW! CHECK IT OUT-- POWER-PACKED PUFFS OF AIR. AIR PRESSURE AND SCIENCE-- THEY'RE POWERFUL. Both: SCIENCE RULES! IT'S A PRETTY GOOD DAY FOR PARASAILING. AH, THAT WAS GREAT. ANYWAY, HERE'S THE PARACHUTE. THIS IS THE FRONT, AND THIS IS THE BACK. BETWEEN THERE, WE GET HIGH PRESSURE. ON TOP, WE GET SLIGHTLY LOWER PRESSURE. THAT DIFFERENCE IN AIR PRESSURE? THAT'S WHERE THE LIFT COMES FROM. WHOA! THAT'S A BOEING 727-- A CLASSIC JETLINER. IT'S FULL OF PEOPLE, KIDS, DOGS, AND CHOICE OF CHICKEN OR BEEF. IT WEIGHS ALMOST 100 TONS. 100 TONS! THAT'S A LOT OF TONS TO GET OFF THE GROUND. HOW DO WE DO IT? EVEN THOUGH WE KNOW THERE'S THOUSANDS OF AIRPLANES TAKING OFF AND LANDING EVERY DAY IT'S STILL A PRETTY COOL THING TO WATCH. WISH WE COULD SEE THAT AGAIN ON INSTANT REPLAY. WE CAN, BILL. BILL? I didn't know you guys were up there. Go ahead. Rewind it. GIVE ME CAMERA ONE. NO, TWO. NO, THREE. Bill: <i> THAT'S GREAT.</i> <i> CHECK OUT THE AIRPLANE'S WING.</i> <i> LOOK AT ITS SHAPE.</i> <i> THAT'S IMPORTANT,</i> <i> BECAUSE AS THE PLANE GETS GOING</i> <i> SOME OF THE AIR'S GOING</i> <i> TO GO OVER THE WING</i> <i> AND SOME OF THE AIR'S</i> <i> GOING TO GO UNDER IT--</i> <i> JUST LIKE THE PLASTIC PLANE</i> <i> OF SCIENCE.</i> THE X's ARE GOING OVER THE TOP FAST. THE O's ARE GOING UNDERNEATH NOT AS FAST. READY TWO. TAKE TWO. <i> IT'S THE SAME AIR</i> <i> JUST TRAVELING</i> <i> AT DIFFERENT SPEEDS</i> <i> WHICH CREATES A DIFFERENCE</i> <i> IN AIR PRESSURE.</i> <i> THE FASTER X's</i> <i> CAN'T PUSH DOWN</i> <i> AS HARD</i> <i> AS THE SLOWER O's PUSH UP.</i> <i> THE O's PUSH THE WING UP.</i> Bill: <i> THE AIR ON TOP</i> <i> ZIPS OVER THE WING</i> <i> WHICH CREATES AN AREA</i> <i> OF LOW PRESSURE.</i> YOU'VE GOT HIGH PRESSURE UNDERNEATH AND LOW PRESSURE ON TOP TO CREATE LIFT. THE X's AND O's GET BACK TOGETHER AT THE BACK OF THE WING. READY FOR BILL? WITH AIR MOVING OVER WINGS WE CAN DEVELOP DIFFERENCES IN AIR PRESSURE THAT CAN BE USED TO CREATE LIFT. HOW DO WE GET AIR MOVING? WITH ENGINES, BIG ENGINES. THAT'S HOW WE GET AIR MOVING. NOW LET'S KEEP THE SHOW MOVING. Woman: <i> THIS IS THE SIMULATOR ROOM.</i> <i> THE ONE WE'RE GOING</i> <i> TO FLY IN TODAY IS THE 767-200.</i> MY NAME IS SUZANNA DARCY. I'M A TEST PILOT FOR THE BOEING COMPANY. I'M RATED TO FLY <i> ON THE BOEING 737,</i> <i> THE 57, THE 67, AND 747-400.</i> <i> THIS IS THE SIMULATOR</i> <i> THAT'S USED FOR DOING</i> <i> ALL THE TRAINING</i> <i> FOR AIRLINE PILOTS</i> <i>AND TEST PILOTS THAT ARE GETTING</i> <i> THEIR RATINGS ON THE 767.</i> ...PULLING BACK HERE. AND BEAUTIFUL. WE'RE FLYING. THERE'S A POSITIVE RATE AND YOU TELL ME GEAR UP. THESE ARE THE THROTTLES AND THEY WORK LIKE AN ACCELERATOR ON A CAR. THIS IS THE CONTROL COLUMN. WHEN YOU PULL BACK, WE GO UP. WHEN YOU PUSH FORWARD, THE AIRPLANE WILL GO DOWN. <i> MOST PEOPLE WOULD NOT</i> <i> CALL PILOTS SCIENTISTS</i> <i> BUT YOU NEED</i> A LOT OF MATH AND SCIENCE. WHEN WE HIT THE GROUND, I PULL THIS BACK? I'LL HELP YOU. THERE'S 50 FEET. THE AIRPLANE STARTS TO FLARE AUTOMATICALLY. RIGHT THERE, TOUCH DOWN. COME UP. <i> YOU CAN FEEL</i> <i> THE BRAKES COMING ON.</i> ALTITUDES ARE NUMBERS. HEADINGS ARE NUMBERS. AIR SPEEDS ARE NUMBERS. AN AIRPLANE IS REALLY JUST A FUN APPLICATION OF MATHEMATICS. ARE YOU SURE YOU HAVEN'T DONE THIS BEFORE? YOU, ME, AIR, EVERYTHING IS MADE OF MOLECULES-- LITTLE PIECES OF STUFF. AND WHEN THINGS LIKE AIR MOLECULES GET MOVING THEY CAN EXERT PRESSURE. HERE. TAKE A LOOK AT THE MOLECULE MACHINE OF SCIENCE. SEE THE LITTLE BALLS? THEY'VE MOVING LIKE MOVING AIR MOLECULES AND THEY EXERT A PRESSURE ON THIS PAPER DISK. NOW, WHAT WOULD HAPPEN IF I MOVED THE PAPER DISK UP REAL FAST? THE MOLECULES SPREAD APART. THEY EXPAND. THEY WANT TO EXERT A PRESSURE IN THE DIRECTION THEY'RE GOING-- ALONG THE TUBE. THEY DON'T EXERT AS MUCH PRESSURE THIS WAY OR THIS WAY. <i> THAT'S BERNOULLI'S PRINCIPLE.</i> IT'S THE SAME PRESSURE YOU FEEL WHEN RIDING YOUR BIKE. EXCUSE ME. I'M GOING TO GENERATE A LITTLE WIND HERE IN THE LAB. YOU FEEL WIND ON YOUR FACE. YOU FEEL PRESSURE. YOU DON'T FEEL AS MUCH PRESSURE ON THE BACK OF YOUR HEAD. THIS PRESSURE IS CALLED DYNAMIC PRESSURE... THE PRESSURE OF MOVING AIR. THE SAME THING HAPPENS ON AN AIRPLANE WING. SUPPOSE WE HAD AN AIRPLANE WING LIKE THE PLASTIC AIRPLANE WING OF SCIENCE. AS AIR GOES OVER IT, THE AIR GOING UNDER EXERTS A LITTLE PRESSURE ON THE BOTTOM BUT THE AIR GOING OVER THE TOP DOESN'T EXERT AS MUCH PRESSURE THIS WAY, THIS WAY, THIS WAY, OR THIS WAY. SO WE GET LIFT. LIFT-- IT'S ALL DONE WITH MOLECULES. SEE YA. HERE'S AN EXPERIMENT YOU CAN TRY THAT SHOWS THE DIFFERENCE BETWEEN HIGH AND LOW AIR PRESSURE. ALL YOU NEED IS SOME STRING, TAPE, A STRAW AND TWO PING-PONG BALLS HUNG UP LIKE THESE. TAKE THE STRAW AND BLOW AIR BETWEEN THE BALLS. WHAT WILL HAPPEN? OKAY, SO YOU HAVE YOUR PING-PONG BALLS SET UP. WHAT DO YOU THINK WILL HAPPEN? YOU MIGHT THINK THAT THE AIR GOING BETWEEN THE BALLS WILL PUSH THEM APART, BUT WHEN YOU TRY IT... THEY GET CLOSER TOGETHER. <i> THAT'S BECAUSE</i> <i> THE FAST-MOVING AIR</i> <i> HAS LOWER SIDEWAYS AIR PRESSURE</i> <i> THAN SLOW-MOVING AIR.</i> <i> SO, THE FASTER AIR</i> <i> GOING BETWEEN THE BALLS</i> <i> MAKES THE PRESSURE ON THEM</i> <i> DROP.</i> <i> SINCE THE AIR OUTSIDE THE BALLS</i> <i> HAS HIGHER PRESSURE</i> <i> IT MOVES THE BALLS</i> <i> CLOSER TOGETHER.</i> THIS IS CALLED THE BERNOULLI EFFECT <i> NAMED AFTER THE SWISS GUY</i> <i> WHO DISCOVERED THIS PRINCIPLE.</i> THE BERNOULLI EFFECT MAKES BIRDS, AIRPLANES, AND KITES FLY. SWITZERLAND IS ALSO KNOWN FOR CHOCOLATES, SWISS CHEESE AND CUCKOO CLOCKS. BERNOULLI-- HE WAS ONTO SOMETHING, HUH? NORTHWEST 7 HEAVY, READY FOR DEPARTURE. NORTHWEST 7 HEAVY RUNWAY 1-6 LEFT, TAXI IN POSITION... Laurence Randolph, Jr.: <i> WHAT I DO FOR A LIVING</i> IS I'M AN AIR TRAFFIC CONTROL SPECIALIST. AIRPORT 21 HEAVY... RUNWAY 1-6 LEFT CLEARED FOR TAKEOFF. Randolph: <i> THE AIRPLANES TALK TO US</i> <i> AT ALL TIMES.</i> <i> FROM THE TIME</i> <i> THEY PUSH BACK OFF THE GATE,</i> <i> UNTIL THEY LAND AGAIN</i> <i> THEY'RE TALKING</i> <i> TO AN AIR TRAFFIC CONTROLLER.</i> <i> OUR JOB INVOLVES SCIENCE</i> <i> EVERY DAY.</i> WIND 20-0-1-0. RUNWAY 1-6 CLEARED TO LAND. <i> I DECIDED TO BE</i> <i> AN AIR TRAFFIC CONTROLLER</i> <i> IN THE SIXTH GRADE.</i> I GOT FASCINATED IN FLIGHT <i> AND DIFFERENT</i> <i> SCIENTIFIC FORMULAS.</i> <i> THEN I FOUND OUT</i> <i> I HAD TO KNOW ABOUT CLOUDS</i> <i> AND PRECIPITATION</i> <i> AND SCIENCE BECAME</i> <i> MY FAVORITE SUBJECT.</i> IN FACT, IT WAS MY BEST SUBJECT. <i> IF YOU FIND OUT</i> <i> WHAT YOU WANT TO DO</i> <i> AT A YOUNG ENOUGH AGE</i> <i> THEN YOU CAN STRIVE FOR IT</i> <i> WHEN YOU GET OLDER.</i> <i> ANYONE CAN ACHIEVE A GOAL</i> <i> IF YOU STRIVE FOR IT</i> <i> AND PUSH FOR IT HARD ENOUGH.</i> Announcer: <i> WRIGHT BROTHERS--</i> <i> FIRST TO FLY AN AIRPLANE</i> <i> WITH AN ENGINE.</i> <i> CHARLES LINDBERGH--</i> <i> FIRST PERSON TO FLY ALONE</i> <i> ACROSS THE ATLANTIC.</i> <i> AMELIA EARHART</i> <i> FIRST WOMAN TO PILOT A PLANE</i> <i> ACROSS THE ATLANTIC.</i> <i> WHAT DO THESE THREE</i> <i> HAVE IN COMMON?</i> <i> ...THIS WEEK</i> <i> ON</i> THE JOHNNY LIFT SHOW. THIS LOOKS LIKE AN ORDINARY WING. IT IS AN ORDINARY WING, ONLY IT'S REALLY SMALL. SCIENTISTS TEST WINGS, NOT IN THE WILD ANYTHING-CAN-HAPPEN WORLD OF THE OUTDOORS BUT IN HERE. THIS IS A WIND TUNNEL. A TUNNEL WITH WIND! <i> REMEMBER WHEN WE WERE FLYING</i> <i>OUR PLASTIC AIRPLANE OF SCIENCE?</i> <i> IT DIDN'T MAKE ANY DIFFERENCE</i> <i> WHETHER WE WERE FLYING IT</i> <i> IN FRONT OF A FAN</i> <i> OR FLYING IT WITH A TOSS.</i> <i> THE WINGS LIFT THE SAME WAY.</i> SEE, PLANES TAKE OFF AND LAND TOWARD THE WIND. THAT WAY, WHETHER THEY'RE SPEEDING UP TO TAKE OFF OR SLOWING DOWN TO LAND THERE'S ALREADY AIR MOVING OVER THE WING. NOT THAT BAD. AIRPLANES CAN GET BIG AND COMPLICATED AND SOMETIMES LOOK A LITTLE WEIRD. SO WE WANT TO MAKE SURE THEY FLY THE WAY WE WANT THEM TO. IT'S EASIER, AND I DARESAY A LOT LESS EXPENSIVE TO TEST WINGS AND AIRPLANES IN HERE THAN IT IS TO GO JUST BUILDING ONE AND SEEING WHAT HAPPENS. THESE BIG ONES FLY GREAT AND THEY WERE ALL TESTED AS MODELS. SOME PEOPLE ARE AFRAID THAT AIRPLANES CAN'T FLY BECAUSE THE AIR THEY FLY THROUGH IS INVISIBLE. SO IS THE AIR WE BREATHE. I MEAN, IT'S JUST AIR. WE HUMANS HAVE FIGURED OUT WAYS TO MAKE PRETTY GOOD WINGS AND THEY DEVELOP DIFFERENCES IN AIR PRESSURE AND DIFFERENCES IN AIR PRESSURE, THAT CREATES... TO GET LIFT, YOU HAVE TO HAVE THE WING MOVING. YOU HAVE TO HAVE THE AIR MOVING. IT'S LIKE HAVING YOUR FACE IN FRONT OF A FAN. OR LIKE WHEN YOU'RE RIDING A BIKE. YOU FEEL THE WIND ON YOUR FACE-- THE PRESSURE OF MOVING AIR. THAT'S WHAT WE CALL... IT'S WHAT MAKES AIRPLANES FLY. A HUMAN ON A BICYCLE IS A VERY EFFICIENT MACHINE. THERE'S AIRPLANES NOW THAT YOU ACTUALLY GET IN AND PEDAL FOR POWER. <i> THIS IS THE GOSSAMER ALBATROSS.</i> <i> IT WAS THE FIRST</i> <i> HUMAN-POWERED AIRPLANE</i> <i> TO FLY ACROSS</i> <i> THE ENGLISH CHANNEL.</i> <i> IT WAS PEDAL-POWERED</i> <i> BY BRIAN ALLEN.</i> <i> DON'T KID YOURSELF.</i> <i> PEDALING HARD AND LONG ENOUGH</i> <i> TO KEEP AN AIRPLANE LIKE THIS</i> <i> FLYING IS NO EASY TASK.</i> Pay attention. <i> YOU GET A WING</i> <i> WITH AN ANGLE OF ATTACK...</i> <i> AND LIFT.</i> <i> ISN'T THAT AMAZING?</i> SCIENCE-- CHECK IT OUT. I HAVE MADE ALMOST A MILLION OF THEM WITH KIDS. OKAY, I PUT A LINE HERE. DID YOU SEE HOW THAT HAPPENED? WE GOT THAT ONE ALL DONE. AND THERE IT IS. AIR PRESSURE. WIND. LIFT. THIS IS SCIENCE. (<i> hums fanfare</i> ) WE GOT ALL OF THEM UP IN THE AIR. (<i> hums fanfare</i> ) THEY'RE FLYING. THEY'RE FLYING. THEY'RE FLYING. CHECK IT OUT. SCIENCE IS COOL. (<i> hums fanfare</i> ) WINGS WILL MAINTAIN LIFT AS LONG AS THEY HAVE AN ANGLE OF ATTACK. LOOK IN HERE. NOT BAD, HUH? HELICOPTER ROTORS WORK JUST LIKE AIRPLANE WINGS. INSTEAD OF FLYING STRAIGHT THROUGH THE AIR, THOUGH THEY ALSO SPIN IN A CIRCLE. <i> THEY DEVELOP DIFFERENCES</i> <i> IN AIR PRESSURE</i> <i> AND THAT DEVELOPS LIFT.</i> THEY WORK GREAT! HELICOPTERS HAVE WINGS THAT SPIN. HERE'S HOW YOU CAN MAKE YOUR OWN HELICOPTER. YOU'LL NEED A PIECE OF CARDBOARD, LIKE A CEREAL BOX A PAIR OF SCISSORS, SOME TAPE, AND A PENCIL. ANYWAY, HERE'S WHAT YOU DO. CUT YOUR HELICOPTER ROTOR BLADES OF SCIENCE LIKE THIS-- NOTCH IT IN FOUR PLACES, HERE, HERE, HERE, AND HERE. BEND IT AT THE END OF THE WING IN OPPOSITE DIRECTIONS TAPE IT TO YOUR PENCIL, AND YOU'RE READY TO GO. TAKE YOUR HELICOPTER AND SPIN IT. SEE? IT FLIES. IT WORKS JUST LIKE A REAL ONE. HERE'S ANOTHER TYPE OF HELICOPTER. CUT A PIECE OF PAPER LIKE THIS. FOLD THESE TWO FLAPS DOWN LIKE THIS. PUT A PAPER CLIP ON THE BOTTOM, AND WATCH IT FLY. Both: HELICOPTERS! SCIENCE! (<i> heavy metal rock intro</i> ) ♪ THE KITES AND PLANES AND BUTTERFLIES ♪ ♪ HAVE THINGS IN COMMON ♪ ♪ ONE'S THE SKY ♪ ♪ THEY ALL CAN SAIL THROUGH THE AIR ♪ ♪ AND BIRDS CAN, TOO, WITHOUT A CARE ♪ ♪ PRESSURE, PRESSURE, PRESSURE, PRESSURE ♪ ♪ PRESSURE, PRESSURE, PRESSURE ♪ ♪ AIR HAS PRESSURE ♪ ♪ AND IT'S MOVING ALL AROUND US ♪ ♪ AND IT'S GROOVING ♪ ♪ NOW THESE CHANGES IN AIR PRESSURE ♪ ♪ CREATE LIFT THAT WE CAN MEASURE, YEAH ♪ ♪ WINGS ARE THE THINGS ♪ ♪ ALTHOUGH NOT LAST ♪ ♪ THE AIR ABOVE THEM MOVES SO FAST ♪ ♪ TRAPPED AIR BENEATH THEM MOVES REAL SLOW ♪ ♪ CREATES HIGH PRESSURE TO LIFT AND GO ♪ ♪ PRESSURE, PRESSURE, PRESSURE, PRESSURE ♪ ♪ PRESSURE, PRESSURE, PRESSURE ♪ ♪ AIR HAS PRESSURE ♪ ♪ AND IT'S MOVING ALL AROUND US ♪ ♪ AND IT'S GROOVING ♪ ♪ NOW THESE CHANGES IN AIR PRESSURE ♪ ♪ CREATE LIFT THAT WE CAN MEASURE ♪ ♪ AIR PRESSURE, AIR PRESSURE ♪ ♪ AIR PRESSURE, AIR PRESSURE ♪ ♪ AIR PRESSURE. ♪ NOW YOU KNOW HOW BIRDS, BATS, BUTTERFLIES AND AIRPLANES FLY. BASICALLY, IT'S THREE THINGS. AIR HAS PRESSURE. TO GET THINGS TO FLY WE WANT DIFFERENCES IN AIR PRESSURE. THOSE DIFFERENCES COME FROM <i> BERNOULLI'S PRINCIPLE.</i> REMEMBER, THE SWISS GUY? AS MOLECULES OF AIR GO THIS WAY THEY DON'T EXERT AS MUCH PRESSURE THIS WAY OR THIS WAY. <i> REMEMBER BERNOULLI'S PRINCIPLE?</i> <i> THE SWISS GUY WITH THE CHEESE.</i> WHEN YOU GIVE A WING AN ANGLE OF ATTACK THEN BERNOULLI'S PRINCIPLE COMES IN AND MAKES LOW PRESSURE ON TOP AND HIGH PRESSURE ON THE BOTTOM. THAT CREATES... <i> I'VE GOT SOME SERIOUS</i> <i> ANGLES OF ATTACK TO DEVELOP.</i> GOTTA FLY. BILL NYE THE SCIENCE GUY. <i> SEE YA!</i> <i> PRODUCED IN ASSOCIATION WITH</i> <i>THE NATIONAL SCIENCE FOUNDATION.</i> ♪<i> BILL, BILL, BILL, BILL,</i> <i> BILL, BILL</i> ♪ ♪ BILL NYE THE SCIENCE GUY ♪ ♪<i> BILL, BILL, BILL, BILL,</i> <i> BILL, BILL</i> ♪ <font color="#ffff00"> Captioning sponsored by</font> <font color="#ffff00"> DISNEY EDUCATIONAL PRODUCTIONS</font> Captioned by <font color="#00ffff"> Media Access Group at WGBH</font> access.wgbh.org ♪ BILL NYE THE SCIENCE GUY ♪ ♪<i> BILL, BILL, BILL, BILL,</i> <i> BILL, BILL</i> ♪ ♪ BILL NYE THE SCIENCE GUY ♪ ♪<i> BILL, BILL, BILL, BILL,</i> <i> BILL, BILL.</i> ♪