>> GRAVITY IS WHAT MAKES THINGS FALL.

>> HEY!

>> GRAVITY IS ONE OF THE FOUR FUNDAMENTAL FORCES OF NATURE.

YOU WANT TO FIND OUT MORE?

SCIENTISTS ARE STANDING GUY ANSWER YOUR QUESTIONS ABOUT GRAVITY.

"D4K" IS NEXT.

>> HI, I'M JOAN CARTAN-HANSEN.

WELL COME TO "D4K."

SUPPOSE HAD YOU TWO OBJECTS OF DIFFERENT SIZE, YOU'RE GOING TO THROW THEM OVER THE SIDE OF THE BUILDING CH.

ONE DO YOU THINK WILL HIT THE GROUND FIRST?

THE BIG ONE OR THE SMALL ONE?

LET'S GIVE IT A TRY.

ONE, TWO, THREE -- THEY HIT ABOUT THE SAME TIME BECAUSE OF GRAVITY.

BEFORE WE GO TO THE STUDIO TO ANSWER YOUR QUESTIONS, LET'S FIND OUT MORE.

GRAVITY IS THE FORCE OF ACTION BETWEEN TWO OBJECTS, IN THIS CASE, BETWEEN A MELON AND THE EARTH.

TO TALK ABOUT GRAVITY, YOU FIRST HAVE TO TALK ABOUT MASS AND MATTER.

MATTER TAKES UP SPACE, AND HAS MASS.

AND MASS IS A MEASUREMENT OF HOW MUCH MATTER SOMETHING HAS.

THE MORE SOMETHING WEIGHS, THE MORE MASS IT HAS, AND THE MORE GRAVITY PULLS ON IT.

YOUR BODY HAS MASS.

AND SO DOES YOUR FRIEND.

SO THERE'S A GRAVITATIONAL PULL BETWEEN THEM.

OH, NO, THAT DOESN'T HAPPEN!

YOUR BODIES DON'T HAVE ENOUGH MASS TO BE PULLED TOGETHER LIKE THAT.

>> EW!

>> BUT THE EARTH'S GRAVITATIONAL PULL IS STRONG BECAUSE IT HAS SO MUCH MASS.

THE GREATERERHE MASS OF THE OBJECT, THE GREATER THE FORCE OF GRAVITY.

ASTRONAUTS COULD BOUNCE EASILY ON THE MOON BECAUSE THE MOON'S GRAVITY IS LESS THAN THE EARTH'S BECAUSE THE MOON HAS LESS MASS THAN THE EARTH.

>> DOES THAT MEAN I WEIGH A DIFFERENT AMOUNT ON DIFFERENT PLANETS?

>> WELL, ON EARTH, SUPPOSE YOU WEIGH 100 POUNDS.

IF YOU WERE ON THE MOON, YOU WOULD WEIGH ABOUT 17 POUNDS.

BUT IF YOU WERE ON A BIGGER PLANET, SAY, JUPITER, YOU'D WEIGH MORE THAN A WHOOPING 236 POUNDS.

AND GRAVITY'S EFFECT DEPENDS UPON HOW CLOSE OBJECTS ARE TO ONE ANOTHER.

THE EARTH'S GRAVITATIONAL PULL ON, SAY, PLUTO ISN'T VERY STRONG, BECAUSE IT'S SO FAR AWAY.

BUT THE EARTH'S GRAVITATIONAL PULL ON THE MOON IS GREAT.

THE EARTH'S GRAVITY KEEPS THE MOON IN ORBIT.

>> SO FIRST GRAVITY IS SO STRONG, HOW DO ASTRONAUTS GET INTO SPACE?

AND WHY DO THEY JUST FLOAT THERE?

>> ASTRONAUTS CAN TAKE OFF FROM EARTH BECAUSE THE POWER OF THE ROCKETS USED TO PUSH THE SPACE SHUTTLE OUT OF EARTH'S ATMOSPHERE.

BUT THEY NEVER TRAVEL BEHIND EARTH'S GRAVITATIONAL PULL.

THEY JUST KEEP MOVING FAST ENOUGH TO KEEP GRAVITY FROM PULLING THEM BACK TO EARTH.

IT'S CALLED A STATE OF WEIGHT NAJIBULLAH ZAZILESSNESS, OR AS NASA CALLS IT, MICROGRAVITY.

THESE BOISE STATE UNIVERSITY ENGINEERING STUDENTS ARE FLYING IN A SPECIAL AIRPLANE THAT CAN CREATE MOMENTS MUCH WEIGHTLESSNESS.

THEY'RE STUDYING THE EFFECTS OF MICROGRAVITY ON ATTRACTION OF DIFFERENT WHEEL TREAD DESIGN ON LUNAR SOIL, AND TESTING WAYS TO FIND OUT HOW MUCH WATER THERE IS IN THE SOIL ON THE MOON OR OTHER PLANETS.

>> BEST FEELING IN THE WORLD!

>> SO GVITY IS ONE OF THE FUNDAMENTAL FORCES IN NATURE.

WE REALLY DON'T KNOW WHAT CAUSES GRAVITY, BUT WE SURE FEEL THE EFFECTS OF GRAVITY.

ARE YOU OK?

>> YEAH.

WHAT GOES UP MUST COME DOWN.

IT'S JUST GRAVITY.

>> AND JOINING ME NOW TO ANSWER YOUR QUESTIONS ABOUT GRAVITY ARE FOUR BOISE STATE UNIVERSITY MICROGRAVITY PROJECT TEAM MEMBERS.

ALEX MILLER, BRIAN PIERRE, JAKE FORSBERG, AND PAMILA WARD.

THANK YOU FOR BEING HERE.

I APPRECIATE YOU JOINING US TODAY.

>> THANK YOU.

>> AND OF COURSE WE WANT TO HEAR FROM YOU.

GIVE US A CALL, TOLL-FREE AT 1-800-973-9800 OR YOU CAN EMAIL US AT D4K@IDAHOPTV.ORG.

>>> LET'S GO TO THE FIRST QUESTION I HAVE, WHAT DOES A MICROGRAVITY TEAM DO?

IT DOESN'T SOUND LIKE YOU COMPETE IN SPORTS, BUT WHAT IS IT?

>> WELL, BOISE STATE'S MICROGRAVITY TEAM WORKS IN COLLABORATION WITH NASA IN THEIR REDUCED GRAFT PROGRAM.

SO WE APPLY FOR DIFFERENT RESEARCH PROJECTS, ESSENTIALLY, AND THEN AFTER A SCHEX PROCESS -- SELECTION PROCESS WE WORK WITH TEAM MEMBERS AT NASA STAFF THERE AND THEN GET TO ACALLY DEVELOP THOSE EXPERIMENT AND RUN THEM ON THE WEIGHTLESS WONDERS, WHICH HELPS US SIMULATE THE WEIGHTLESS ENVIRONMENT THAT WE NEED TO DO THEM.

>> OK.

LET'S GO TO OUR FIRST QUESTION FROM MRS.

PETERSON'S CLASS.

COLE WOULD LIKE TO KNOW, WHAT CAUSES GRAVITY?

DO WE KNOW WHAT CAUSES GRAVITY?

>> WELL, GRAVITY IS CAUSED BY THE MASS OF OBJECTS, SO SOMETHING LIKE EARTH OR THE MOON HAS GRAVITY BECAUSE IT'S -- BECAUSE OF HOW LARGE IT WEIGHS AND HOW MUCH MASS IT HAS.

AND SO ALL THAT MASS, THE LARGER THE MASS THE MORE GRAVITY SOMETHING HAS.

THAT'S WHY THE MOON HAS LESS MASS AND LESS GRAVITY THAN EARTH DOES.

>> SO THAT'S WHY YOU -- WE SEE PICTURES OF ASTRONAUTS ON THE MOON AND THEY WERE REALLY BOUNCING AROUND.

QUINN WOULD LIKE TO KNOW, WHY ISN'T THERE GRAVITY IN SPACE?

IS THERE GRAVITY IN SPACE?

>> YEAH.

ACTUALLY, THERE IS GRAVITY IN SPACE.

THERE'S GRAVITY EVERYWHERE.

ON THE EARTH WE FEEL GRAVITY, IT PULLS US TO THE GROUND, BUT WHEN YOU SEE ASTRONAUTS IN SPACE, IT APPEARS THERE'S NO GRAVITY, THEY SEEM TO BE FLOATING AROUND.

BUT THEY'RE REALLY NOT ACTUALLY FLOATING, THEY'RE ACTUALLY, GRAVITY IS AIVING THEM JUST LIKE IT'S AFFECTING US ON EARTH IN THE SAME WAY.

THEY'RE JUST MOVING AT A RATE SO FAST, THEY'RE MOVING PAST THE AIR AS THEY FALL AND THEY CONTINUE TO ORBIT AROUND IT.

AND SO YOU SEE THEM AGAINST THE INTERNATIONAL SPACE STATION, AND THEY APPEAR TO BE FLOATING, BUT THEY'RE ACTUALLY JUST MOVING WITH THE INTERNATIONAL SPACE STATION IN A STATE OF WAITLESSNESS OR FREE FALL.

>> LIKE YOU'RE TRAVELING IN A CAR, YOU DON'T FEEL LIKE YOU'RE TRAVELING 50 MILES AN HOUR, BUT YOU ARE.

>> YES.

>> OK.

OK.

SAM WANTS TO KNOW, WHAT IF AN ASTRONAUT ONLY WORE A HELMET AND NOT A SUIT IN SPACE?

THAT'S NOT ACTUALLY A GRAVITY QUESTION, BUT -- >> WELL, IN SPACE THERE'S NO OXYGEN, SO IF THE ASTRONAUT DIDN'T WEAR A HELMET, THEY COULDN'T BE ABLE TO BREATHE.

>> CALEB WOULD LIKE TO KNOW HOW FAST DO YOU HAVE TO GO TO ESCAPE THE ATMOSPHERE?

>> WELL, FRANKLY, YOU CAN ESCAPE THE ATMOSPHERE AT ANY SPEED THAT YOU WANT, BUT ON EARTH THERE'S A TERM CALLED ESCAPE VELOCITY, WHICH IS THE SPEED HAVE YOU TO BE GOING IF YOU HAD NO MORE PROPULSION, THE SPEED THAT YOU WOULD NEED TO GO TO NEVER COME BACK TO EARTH, ESSENTIALLY.

AND FOR EARTH, THAT'S ABOUT SEVEN MILES A SECOND, WHICH IS VERY, VERY FAST.

BUT IF YOU WERE ABLE TO NEGLECT THINGS LIKE AIR RESISTANCE AND YOU WERE ABLE TO, SAY, FIRE A GUN STRAIGHT UP IN THE AIR AT SEVEN MILES A SECOND, THAT BULLET WOULD NEVER COME BACK TO THE EARTH.

>> BECAUSE IT COULD GET OUT.

TAYLOR IN MRS.

PETERSON'S CLASS WOULD LIKE TO KNOW, WHY DOES TIME CHANGE IN A BLACK HOLE?

DOES GRAVITY CHANGE ALSO?

THAT'S A PRETTY COMPLICATED QUESTION.

>> THAT'S A REALLY COMPLICATED QUESTION.

>> DOES TIME CHANGE IN A BLACK HOLE?

>> IN THEORY, WE BELIEVE IT DOES.

AND SO THAT'S KIND OF A VERY HIGH-END THEORETICAL PHYSICS QUESTION, WHICH I GUESS WITH E-- WE CAN'T ANSWER HERE.

>> WE'LL START WITH GRAVITY.

KYLE WOULD LIKE TO KNOW, WILL SATURN SMOOSH YOU LIKE A PANCAKE BECAUSE IT HAS SO MUCH GRAVITY?

>> I ACTUALLY DON'T KNOW THE EXACT MASS OF SATURN, BUT I DO KNOW IT'S MUCH MORE MASSIVE THAN THE EARTH IS.

AND SO IF WE WERE TO GO TO SATURN, AND STAND ON ITS SURFACE, WE WOULD FEEL MUCH MORE FORCED TOWARDS ITS SURFACE.

DEPENDING ON HOW -- FITS MORE MASSIVE, IT'S POSSIBLE IT COULD SMOOSH US.

>> ALONG THAT SAME LINE, IN MRS.

HUNT'S CLASS AT CYNTHIA MANN ELEMENTARY, HOW DOES GRAVITY PULL US TO THE GROUND?

I DON'T -- I DON'T REALLY FEEL LIKE GRAVITY IS PULLING ME DOWN, BUT WE KNOW THAT IT IS.

>> RIGHT.

THE GRAVITY IS PULLING DOWN -- IT'S OBVIOUS, IT'S -- ALEX?

[LAUGHTER] >> IT'S KIND OF ONE OF THOSE INTERESTING THINGS TOO, I GUESS YOU DON'T NOTICE UNTIL IT'S GONE.

OR UNTIL YOU'VE FELT BEING WEIGHTLESS, I GUESS.

IF YOU WERE ABLE TO SKY DIVE, ESSENTIALLY, YOU CAN KIND OF FEEL HOW YOU FEEL LIGHTER AND EVERYTHING INSIDE YOU, IF YOU'RE ON A ROLLER COASTER, IT STARTS THE TO COME UP, SO YOU CAN ACTUALLY FEEL GRAVITY PULLING YOU DOWN, BUT I GUESS IT'S SO NORMAL THAT WE DON'T REALLY NOTICE ANYMORE.

>> REAGAN FROM MRS.

HUNT'S CLASS WOULD LIKE TO KNOW, DOES THE SUN KEEP PLUTO IN ORBIT?

IS IT SO STRONG, DOES THAT AFFECT PLUTO AS WELL?

>> YES.

IT'S SO HUGE, IT'S MUCH, MUCH, MUCH BIGGER THAN EARTH, AND IT'S ABLE TO KEEP ALL THE PLANETS IN THE ORBIT, BECAUSE ITS GRAVITATIONAL PULL IS SO LARGE, IT'S EVEN ABLE TO KEEP POLLUTE 0, WHICH IS -- PLUTO, WHICH IS REALLY FAR AWAY IN ORBIT.

>> KIND OF ALONG THOSE SAME LINES, VICTOR WOULD LIKE TO KNOW IF THE MOON HAS GRAVITY.

DOES EVERYTHING THAT HAS MATTER OR MASS HAVE GRAVITY?

>> YEAH.

EVERYTHING, ABSOLUTELY EVERYTHING IN THE UNIVERSE HAS GRAVITATIONAL FORCE ASSOCIATED WITH IT.

AND EVEN ME AND YOU HAVE GRAVITY, AND WE'RE DSHT WAY THE EARTH PULLS ON US TOWARD THE CENTER,OWARDS THE SURFACE, WE'RE PULLING ON THE EARTH THE SAME WAY.

WE JUST HAVE LESS MASS.

OUR PULL IS NOT AS GREAT AS THE PULL ON US.

SIMILAR, THE MOON HAS GRAVITY AS WELL, AND IT PULLS US TOWARDS ITS SURFACE, BUT THE EARTH IS SO MUCH LARGER, IT'S KEEPING US DOWN.

SO IF WE WERE TO GO ON THE MOON WE'D FEEL ITS GRAVITY, IT WOULD JUST BE -- THE PULL WOULD BE MUCH LESS, WE'LL BE ABLE TO JUMP HIGHER, LIKE YOU SEE ASTRONAUTS DO WHEN THEY'RE ON THE SURFACE OF THE MOON.

>> HOW DO WE SEE THE MOON GRAVITY AFFECT US ON EARTH?

>> AFFECT US ON EARTH?

WELL, WE SEE HOW TIDES OF THE OCEAN CAN CHANGE.

THAT'S CAUSED BY THE GRAVITATIONAL PULL OF THE MOON.

>> A GOOD EXAMPLE.

FROM MRS.

SWEITZER'S FOURTH GRADE ASS AT RIVERSIDE ELEMENTARY, LAUREN WOULD LIKE TO KNOW, WHY DO FEATHERS FLOAT?

>> FEATHERS FLOAT BECAUSE OF THE AIR RESISTANCE.

SINCE THE FEATHER HAS MORE SURFACE AREA AS IT'S COMING DOWN, THE AIR IS PUSHING UP ON IT.

SO IT'S ABLE TO PUSH UP ON IT ENOUGH THAT IT ESSENTIALLY KIND OF CANCELS OUT GRAVITY, MAKES GRAVITY LESS, FALLS SLOWER TO THE GROUND.

AIR IS CATCHING IT.

>> BUT WHEN WE PUSH THE WATERMELON AND THE CANTALOUPE AT THE SAME TIME, THEY HIT ABOUT THE SAME TIME.

>> BECAUSE THEY DON'T HAVE THAT SURFACE AREA, THAT FLAT AREA WHERE THE AIR CAN PUSH BACK UP ON IT.

IT'S CIRCULAR.

>> OK.

>> IT FUNNELS RIGHT THROUGH THE AIR.

>> ISABEL WOULD LIKE TO KNOW, WHY DO WE NEED GRAVITY?

WHY IS GRAVITY SOMETHING WE HAVE TO HAVE?

>> WELL, GRAVITY AFFECTS US IN A LOT OF WAYS, AND I CAN SAY I GUESS THE SAME THING YOU MIGHT NOT EVEN REALIZE HOW MANY DIFFERENT WAYS IT AFFECTS US UNTIL IT'S GONE, WHICH HOPEFULLY I FEEL CONFIDENT THAT WON'T HAPPEN ANY TIME SOON.

BUT IN FACT, THE REASON WHY THE EARTH AND THE SOLAR SYSTEM IS EVEN THE WAY THEY ARE IS BECAUSE THEY CONDENSED OUT OF GAS ESSENTIALLY INTO SOLID PLANETS AND THINGS, BECAUSE THEIR GRAVITATIONAL ATTRACTION OVER A LONG TIME.

SO WE HAVE PRETTY MUCH GRAVITY TO THANK FOR A LOT OF THINGS.

>> IF THERE WERE NO GRAVITY, WE WOULDN'T BE HERE.

>> YEAH.

>> IS THAT A SIMPLE ANSWER?

LET'S GET TO AN EMAIL QUESTION.

THIS IS FROM ADAM, HE'S HOME SCHOOLED AND WOULD LIKE TO KNOW, WHAT CAUSES BLACK HOLES?

>> ALEX CAN TAKE THAT ONE.

>> YOU'RE A BLACK HOLE EXPERT.

>> WELL, I GUESS NOT AN EXPERT, BUT STEVEN HAWKING WOULD BE THE GUY TO ASK ABOUT THAT.

HE'S ONE OF THE PEOPLE WHO FIRST THEORIZED ABOUT BLACK HOLES.

AS YOU MIGHT GUESS, I GUESS GRAVITY IS A MAJOR FACTOR IN BLACK HOLES, BUT BLACK HOLES ARE SUSPECTED TO BELIEVE -- ARE SUSPECTED TO BE ESSENTIALLY VERY, VERY MASSIVE OBJECTS, LIKE MANY, MANY TIMES THE MASS OF THE SUN, THAT IF COLLAPSED IN ON THEMSELVES BECAUSE OF THEIR OWN GRAVITY, TO A POINT WHERE THEY ARE VERY, VERY TINY AND THEY HAVE SO MUCH GRAVITY THAT NOTHING CAN ESCAPE THEM.

INCLUDING LIGHT, WHICH IS WHY WE CALL THEM BLACK HOLES.

>> SO THAT'S OBVIOUSLY SO IF THE LIGHT CAN'T GET OUT, THERE'S NOTHING FOR YOUR EYES TO SEE.

>> YES.

>> WHAT ELSE DO WE KNOW ABOUT BLACK HOLES?

>> WELL, THERE ARE SEVERAL KNOWN BLACK HOLES.

FOR A WHILE THEY WERE JUST THEORETICAL, AND NOW WE'RE FAIRLY CERTAIN WE'VE FOUND SEVERAL OF THEM, AND MANY OF THE VERY LARGE ONES ARE ACTUALLY AT THE CENTER OF OUR GALAXY.

BASICALLY ACTING AS THE VERY PINWHEEL OF IT THAT WE SPIN AROUND.

>> THERE WAS A QUESTION, IF YOU SEANT CAMERA INTO A BLACK HOLE, WOULD YOU GET ANYTHING OUT?

OR CAN YOU SEND A CAMERA INTO A BLACK HOLE?

>> WELL, THE ANTS WOULD BE YES, WE COULD SEND SOMETHING INTO A BLACK HOLE, BUT THE QUESTION OF GETTING ANYTHING OUT AGAIN APPEARS TO BE PRETTY SLIM.

ANYTHING THAT GOES INTO BLACK HOLES PRETTY MUCH DOESN'T COME OUT, SEEING AS LIGHT CAN'T ESCAPE, IT'S VERY DIFFICULT TO HAVE ANYTHING ELSE TRAVEL FAST ENOUGH TO BE ABLE TO GET AWAY FROM IT.

>> GRACE AT RIVERSIDE ELEMENTARY WOULD LIKE TO KNOW, ARE THERE ANY MOLECULES IN GRAVITY?

>> I WOULD LIKE TO SAY GRAVITY IS A FORCE, BUT I'M NOT SURE IF THERE WOULD BE MOLECULES OR NOT.

IT'S NOT SOMETHING WE CAN SEE READILY.

>> MOLECULES ARE HARD TO SEE, BUT GRAVITY YOU CAN'T REALLY SEE.

THAT'S -- LET ME TOSS THE QUESTION -- DO WE KNOW WHAT GRAVITY IS?

OR DO WE ONLY KNOW WHAT GRAVITY ISN'T?

>> WE DON'T KNOW EXACTLY WHAT GRAVITY IS, BUT THERE'S THEORIES ON WHAT CAN CAUSE IT.

ONE OF THEM IS A TYPE OF PARTICLE.

I BELIEVE IT'S CALLED A GRAVITON.

SO SOME PEOPLE THEORIZE PARTICLES ARE ACTUALLY CAUSED IN GRAVITY, AND THE OTHER THEORY IS THAT MASS ACTUALLY IS BENDING SPACE.

AND AS OBJECTS MOVE, THEY'RE MOVING WITH THE BEND OF THE SPACE THAT THE MASS CREATED.

AND THEY BEND SPACE AND THEY SINK IN TOWARDS EACH OTHER.

THAT'S ONE THEORY.

>> IN SHORT, WE'RE NOT ENTIRELY CERTAIN, I GUESS, WHAT GRAVITY IS.

HOPEFULLY FOR FUTURE GENERATIONS WE'LL WORK ON THAT AND FIGURE OUT WHAT IT IS.

>> LET'S SEE IF WE CAN GET TO OUR FIRST CALLER.

ASHLEY IN WASHINGTON?

ARE YOU THERE?

>> Caller: YES.

>> GO AHEAD.

>> Caller: DOES GRAVITY HAVE TO DO WITH -- >> DOES GRAVITY HAVE SOMETHING TO DO WITH OBJECTS GETTING OUT OF A BLACK HOLE?

>> Caller: IN.

>> INTO A BLACK HOLE.

OK.

YOU'RE OUR BLACK HOLE GUY.

>> ALL RIGHT.

WELL, GRAVITY DOES AFFECT THINGS BEFORE THEY ACTUALLY ENTER THE BLACK HOLE.

IT'S KIND OF THE SAME AS GRAVITY IS EVERYWHERE, EVEN IF YOU'RE VERY FAR AWAY FROM A BLACK HOLE, YOU'D BE ABLE TO FEEL ITS GRAVITY, AND IT WOULD PULL THINGS IN TOWARDS IT.

THERE'S A CERTAIN AREA AROUND THE BLACK HOLE CALLED THE EVENT HORIZON, WHICH IS THE POINT WHERE IT ACTUALLY BECOMES BLACK, AND THE GRAVITY IS SO MUCH THAT LIGHT CAN'T ESCAPE.

SO THAT IS KIND OF THE EDGE OF WHAT THEY CALL BLACK HOLE.

THE EVENT HORIZON.

>> DOES THAT ANSWER YOUR QUESTION?

I THINK IT DOES.

THANK YOU VERY MUCH.

OK.

LET'S GET TO LILY IN MRS.

BALL'S CLASS AT SUNNYSIDE ELEMENTARY, WHY IS THERE JUST SOME GRAVITY IN SPACE AND MORE ON EARTH?

WHEN WE -- WE GET THIS QUESTION A LOT.

IT'S HARD TO UNDERSTAND.

LET ME HAVE YOU GUYS TRY AND TAKE A CRACK AT IT.

WHY IS THERE LESS GRAVITY IN SOME PARTS OF THE UNIVERSE AND MORE GRAVITY IN OTHER PARTS OF THE UNIVERSE?

>> WELL, THE FORCE YOU FEEL FROM GRAVITY IS DEPENDENT ON HOW CLOSE YOU ARE TO ANOTHER MASSIVE OBJECT.

SO WE'RE VERY CLOSE TO THE EARTH, SO WE FEEL ITS GRAVITATIONAL PULL THE MOST.

BUT IF WE WERE TO LEAVE THE EARTH AND WE WERE TO ESCAPE ITS GRAVITATIONAL PULL AND GO NEXT TO SOMETHING THAT'S LESS MASSIVE MASSIVE, OR AS WE GET FARTHER AWAY FROM THE EARTH WE FEEL LESS OF ITS PULL.

AND SO -- YEAH.

>> SO IF YOU GET CLOSER TO JUPITER YOU FEEL ITS PULL.

>> YES.

>> DEPENDS ON MASS AND DISTANCE.

>> MASS AND DISTANCE.

THOSE ARE THE TWO THINGS.

LET'S GO TO OUR NEXT CALLER.

LET'S SEE IF WE CAN GET -- SARAH IN EAGLE.

SARAH?

ARE YOU THERE?

>> Caller: YEAH.

I WAS WONDERING HOW YOU CAN MAKE ZERO GRAVITY ON AN AIRPLANE.

>> HOW DO THEY MAKE ZERO GRAVITY ON AN AIRPLANE.

WHAT A GREAT QUESTION.

>> WELL, WHEN THE AIRPLANE TAKES OFF, YOU ACTUALLY FEEL MORE GRAVITY PULLING DOWN ON YOU BECAUSE OF THE FORCES OF THE PLANE MOVING UP SO FAST THAT YOU'RE PULLING BACKWARDS AGAINST EARTH.

AND THEN AS YOU NOSE OVER THE TOP AND THEN YOU START TO FREE FALL PRETTY MUCH, IT'S LIKE YOU'RE FREE FALLING IN THE AIRPLANE, AND WHILE YOU'RE FREE FALLING IN THE AIRPLANE, YOU'RE FLOATING UP AND THE AIRPLANE IS FALLING AND YOU'RE FALLING, AND YOU CAN JUST FLOAT AROUND.

>> WE HAVE SOME SHOTS OF YOU GUYS -- >> HERE WE ARE.

>> SO THE PLANE IS BASICALLY DOING A PARABOLA, UP AND DOWN, UP AND DOWN.

>> LIKE A GIANT ROLLER COASTER.

>> IS IT WHEN IT'S AT THE TOP THAT'S WHEN YOU FEEL WEIGHTLESSNESS.

>> RIGHT AT THE TOP IT'S CHANGING, AND AS YOU'RE FOLLOWING IN THE AIRPLANE YOU'RE FEELING WEIGHTLESSNESS.

>> IT'S NOT REALLY ZERO GRAVITY, IT'S THAT YOU'RE FALLING AT THE SAME RATE OF GRAVITY SO YOU DON'T FEEL THE EFFECTS OF GRAVITY ON YOU.

>> SO YOU GET TO FLOAT.

>> YES.

>> IS IT COOL?

>> IT'S SO COOL.

>> IT'S VERY COOL.

>> SARAH, THANK YOU FOR YOUR QUESTION.

LET'S GET TO -- LET ME ASK THIS NEXT QUESTION, AND THEN I'LL ASK YOU ABOUT YOUR EXPERIMENTS.

LEXI IN SPOKANE.

ARE YOU THERE?

>> Caller: IS ARES -- ERIS A REAL PLANET?

>> I'VE NEVER HEARD OF IT.

>> I THINK YOU MAY HAVE STUMPED THEM.

IF WE FIND OUT, I'LL SEND YOU AN EMAIL.

>> Caller: OK.

>> THANK YOU.

LET ME ASK YOU ABOUT YOUR EXPERIMENTS.

HAD YOU TWO EXPERIMENTS, SO WHO -- THERE WAS ONE WORKING ON THE WHEEL, WHO WORK ORDER THAT ONE?

>> WE WERE BOTH -- >> TELL ME ABOUT THAT.

>> WELL, WE HAD A WHEEL AND IT WAS ON A CARRIAGE, AND WE WERE MEASURING THE EFFECTS OF DIFFERENT VELOCITIES AND THE SLIPPAGE OF THE WHEEL THAT IT WOULD HAVE WHILE IT WAS IN LIEU NAR GRAVITY.

SO IF IT WERE ON THE MOON, HOW MUCH WLD IT SLIP COMPARED TO IF IT WERE ON EARTH, HOW MUCH WOULD THAT WHEEL SLIP.

>> WHY DO YOU NEED TO KNOW THAT?

>> WELL -- >> IT'S COMPLICATED.

>> GO AHEAD, ALEX.

>> I GUESS WE'RE MOSTLY INTERESTED IN HOW MUCH TRACTION WE CAN GET ON THE MOON VERSUS EARTH, SO THAT WE CAN SEND PROBES THERE, OR ROVERS OF SOME SORT AND KIND OF BE ABLE TO PREDICT WHAT KIND OF TRACTION WE CAN EXPECT TO GET.

SO IN TERMS OF LIKE HOW MUCH PARTICULAR EQUIPMENT YOU CAN ACTUALLY SUCCESSFULLY TOW AROUND AND HOW MUCH POWER YOU'LL NEED TO DO THAT.

>> SO GRAVITY AFFECTS EVEN IF YOU'RE GOING TO DRIVE A CAR ON THE MOON, IT MAKES A DIFFERENCE.

>> YEAH.

VERY MUCH.

>> AND THE OTHER EXPERIMENT WAS ON LUNAR SOIL.

DID YOU HANDLE THIS ONE?

>> YES.

>> TELL US ABOUT IT.

>> WELL, IT'S A LITTLE HARDER TO EXPLAIN.

WHAT WE WERE TRYING TO DO IS SEE IF WE COULD DETECT WATER IN SOIL, AND IF THAT WOULD CHANGE WITH LESS GRAVITY.

AND SO BASICALLY WHAT WE'RE DOING, WE TOOK CONTAINERS, AND WE PUT LUNAR SOIL IN IT, AND THEN KNOWN AMOUNTS OF WATER, AND ELECTRICITY IN THE -- SENDING IT THROUGH THE CUP.

WE MEASURE THE ELECTRICITY AND THEN WE COULD TELL HOW MUCH WATER WAS IN THE CUPS.

SO WHEN WE PUT IT ON THE AIRPLANE WITH LESS GRAVITY, WE WANTED TO SEE IF THAT WOULD CHANGE THE MEASUREMENTS.

SO, FOR EXAMPLE, IF THEY WERE ON THE MOON, THEY WOULD BE ABLE TO DETECT THE WATER, KNOWN AMOUNTS OF WATER.

>> AND WERE YOU ABLE TO NOTICE A DIFFERENCE?

>> YES.

IT WAS VERY GOOD, IT RAN WELL.

>> WE HAD DEFINITELY NOTICED -- A NOTICEABLE CORRELATION BETWEEN GRAVITY AND THE MEASUREMENTS THAT WE TOOK.

SO AS WE CHANGED GRAVITY, THE ELECTRICAL MEASUREMENTS THAT WE TOOK OF THE SOIL ACTUALLY CHANGED WITH IT, WHICH IS PRETTY EXCITING.

THAT'S WHAT WE WERE LOOKING FOR.

>> SO EVENTUALLY THEY'LL SEE IF THERE'S WATER ON THE MOORNTION OR ON OTHER PLACES WHERE GRAVITY IS LESS -- >> RIGHT.

>> THAT'S REALLY COOL.

I WANT TO KNOW, WHAT WAS THE BEST PART ABOUT FLYING ON THE AIRPLANE?

>> WELL, FRANKLY, DOING OUR EXPERIMENTS TOOK A FAIR AMOUNT OF CONCENTRATION TO THE POINT FOR OUR PARTICULAR EXPERIMENT, YOU DIDN'T ACTUALLY GET TO ENJOY IT QUITE AS MUCH AS YOU WOULD HAVE HOPED TO.

WHEN YOU'RE ON THE PLANE, THE PLANE CAN ACTUALLY ONLY SIMULATE ABOUT 30 SECONDS OF REDUCED GRAVITY AT A TIME, SO -- BECAUSE YOU'RE FLYING IN A PLANE, YOU -- YOU'RE FALLING TOWARDS THE EARTH, YOU CAN'T KEEP GOING DOWN FOREVER, BECAUSE EVENTUALLY YOU'LL HIT THE GROUND.

SO THEY HAVE TO PULL OUT AND THEN DO IT AGAIN.

SO OVER THOSE SHORT PERIODS, IT WAS KIND OF INTERESTING TO TRY AND GET ALL YOUR WORK DONE.

BUT I WOULD DEFINITELY SAY THE FLOATING WAS A BONUS AT THE END.

WE DID GET SOME TIME AWAY FROM OUR EXPERIMENT TO HAVE FUN.

>> LET ME ASK WHY THE FOUR OF YOU DECIDED THIS IS WHAT YOU WANTED TO DO AS A CAREER.

WHY IS THIS A JOB YOU WANT TO DO?

>> ACTUALLY, I STUDIED COMPUTER SCIENCE, WHICH IS A BRANCH OF ENGINEERING, AND I ACTUALLY DECIDED TO STUDY COMPUTER SCIENCE AND SCIENCE IN GENERAL BECAUSE I WAS INTERESTED IN SPACE OR DOES MOL IS THE FORMAL TERM, AND I REALIZED THAT IT'S POSSIBLE TO CONTRIBUTE TO SPACE RESEARCH AND SPACE EXPLORATION, AND I WANTED TO GO DOWN THAT PATH.

>> WHY DID YOU WANT TO BECOME A SCIENTIST?

>> I REALLY LIKE KNOWING HOW THINGS WORK, AND I JUST HAVE A CURIOUS MIND.

I LIKE TO LOOK INTO THOSE THINGS.

>> AND IF SOMEONE THINKS MAYBE I WANT A SCIENCE -- FLY IN SPACE, OR LEARN ABOUT GRAVITY, WHAT WOULD YOU RECOMMEND?

WHAT WOULD YOU RECOMMEND THEY STUDY?

>> WELL, THERE'S ACTUALLY A LOT OF DIFFERENT WAYS TO GET INTO SPACE OR CONTRIBUTE TO AMERICA'S AND THE WORLD'S EXPLORATION OF SPACE.

SCIENCE IS ONE OF THE MAJOR WAYS THAT THEY DO IT, S STUDYING ANY KIND OF SCIENCE, BUT EVEN TEACHERS WHO ARE NOT TECHNICALLY TRAINED, LIKE BARBARA MORGAN, HAVE GOTTEN TO GO INTO SPACE.

SO THERE'S MANY DIFFERENT WAYS, BUT NASA DOES HAVE A LOT OF ENGINEERS AND SCIENTISTS THAT THEY EMPLOY.

>> AND BARBARA GOT TRAINED.

>> YES.

>> AND HOW -- WHAT ADVICE WOULD YOU GIVE TO THE STUDENTS WHO ARE WATCHING WHO ARE INTERESTED IN MAYBE DOING THIS AS A JOB?

>> I WOULD THINK IF THEY LIKE TINKERING WITH THINGS, OR IF THEY LIKE MATH OR SIGNS AT ALL, ENGINEERING IS A GREAT FIELD.

AND A GREAT JOB OPPORTUNITY, AND IF YOU WANT TO GO TO SPACE OR WORK WITH SPACE EXPLORATION, THEN ANY SORT OF SUBJECTS WITH MATH OR SCIENCE IS A GREAT OPPORTUNITY TO DO SO.

>> DO YOU HAVE ANY ADVICE FOR STUDENTS?

>> SOMETIMES MATH IS ROUGH, BUT IT'S VERY REWARDING.

>> KEEP PLUGGING AT IT.

>> YES.

>> MY ADVICE IS TO JUST FOLLOW WHATEVER PASSION YOU V. EVEN FITS OUTSIDE OF SCIENCE.

JUST TO GO WITH WHAT YOU LIKE TO DO AND WORK HARD AT IT.

AND TRY AND ENJOY SCHOOL AS MUCH AS YOU CAN, BECAUSE IT'S VERY WORTH IT ALL THE WAY THROUGH HIGH SCHOOL AND ALL THE WAY THROUGH COLLEGE.

>> OK.

AND THEN WHERE DO YOU -- YOU'VE GRADUATED, AND YOU'RE INTO GRAD SCHOOL?

>> STUDENT.

>> AND YOU ARE ALL SENIORS AND -- >> I'VE GRADUATED.

>> AND YOU'VE GRADUATED?

>> I'M A SENIOR.

>> SO YOU'RE HEADING OUT THERE.

GOOD LUCK.

>> THANK YOU.

>> THANK YOU VERY MUCH.

>> I APPRECIATE YOU COMING ON THE SHOW TODAY.

IT WAS KIND OF YOU TO ANSWER QUESTIONS.

AND THANK YOU, I WANT TO MAKE SURE I GET EVERYBODY'S NAME -- ALEX MILLER, BRIAN PIERRE, JAKE FORSBERG, AND PAMILA WARD.

THANK YOU ALL.

I APPRECIATE YOU ALL JOINING US.

THERE'S LOTS MORE TO LEARN ABOUT GRAVITY.

YOU CAN GO TO OUR WEBSITE, AT IDAHOPTV.ORG/D4K, CHECK OUT OUR WEB-ONLY SHOW, CHECK IT OUT AT IDAHOPTV.ORG AND CLICK ON "D4K."

OUR NEXT SHOW WE'LL BE TAKING QUESTIONS ABOUT EXO PLANETS, THE PLANETS OUTSIDE THE SOLAR SYSTEM.

SEND IN A QUESTION, AND WE'LL SEE YOU NEXT TIME ON "D4K."

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