Curious About Gravity

In episode 202, we get curious about gravity for Eva of Tel Aviv, Israel and Daniella of Singapore.  We learn what gravity is, why it is so important, and how it was discovered.  We hope you gravitate towards this episode and give it a listen!

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Transcript

PODCAST 202: CURIOUS ABOUT GRAVITY

RELEASE DATE: SUNDAY, AUGUST 14TH, 2022

D:  HELLO, AND WELCOME BACK TO THE CURIOUS KID PODCAST.  THIS WEEK, WE ARE GOING TO LEARN A LOT MORE ABOUT A TOPIC THAT WE’VE COVERED A LITTLE BIT IN PREVIOUS EPISODES, CURIOUS ABOUT THE MOON AND CURIOUS ABOUT OCEANS.  I THINK THE TOPIC IS IMPORTANT ENOUGH THAT IT SHOULD GET IT’S VERY OWN EPISODE.  IN FACT, OUR TOPIC IS SO IMPORTANT, THAT IF IT DIDN’T EXIST, WE WOULD ALL JUST START FLOATING AWAY INTO SPACE.  

O:  DOUBLE-MAILBAG!

D:  DOUBLE-MAILBAG!

“HELLO JACOB AND OLIVIA, MY NAME IS EVA (PRONOUNCED AVA).  I LIVE IN TEL AVIV, ISRAEL, BUT I LIVE ALL OVER THE WORLD.  MY FRIENDS RECOMMENDED THE PODCAST TO ME WHEN I VISITED THEM IN U.S.A.  I WOULD LIKE TO GET CURIOUS ABOUT TOMATO SOUP, GRAVITY, AND FLEXIBILITY.

THANK YOU, FROM EVA (PRONOUNCED AVA).”

*** VM FROM DANIELLA OF SINGAPORE ***

O:  WOW.  WE ARE SO LUCKY TO HAVE LISTENERS GETTING CURIOUS WITH US FROM ISREAL AND SINGAPORE.  WE CAN’T WAIT TO LEARN MORE ABOUT GRAVITY FOR EVA (PRONOUNCED AVA) AND DANIELLA.

D:  I HAVE TO SAY THAT THE VOICEMAIL FROM DANIELLA IS ONE OF THE MOST ADORABLE THINGS I’VE EVER HEARD.  WE LOVE GETTING E-MAILS FROM OUR LISTENERS, AND MESSAGES ON FACEBOOK, INSTAGRAM, AND TWITTER, BUT THERE IS SOMETHING REALLY SPECIAL ABOUT GETTING A VOICEMAIL FROM ONE OF OUR INCREDIBLE LISTENERS.

O:  THAT VOICEMAIL FROM DANIELLA WAS SO CUTE.  IT REMINDS ME OF MYSELF WHEN I WAS 6 YEARS OLD.  

D:  I TOTALLY GET THAT.  MAYBE DANIELLA SHOULD START HER OWN PODCAST.  ALRIGHT, LET’S GET THE LEARNING STARTED WITH THE QUESTION OF THE WEEK.

O:  THE GRAVITY ON MARS IS WEAKER THAN THE GRAVITY HERE ON EARTH.  THAT MEANS THAT WE WOULD ALL WEIGH LESS IF WE WERE STANDING ON MARS.  THE QUESTION OF THE WEEK IS, CAN YOU GUESS HOW MUCH A ONE HUNDRED POUND PERSON WOULD WEIGH ON MARS?

D:  GRAVITY IS A VERY INTERESTING TOPIC, BECAUSE IT IS SOMETHING WE CAN’T LIVE WITHOUT, BUT IT’S ALSO SOMETHING THAT’S INVISIBLE.  THAT MAKES IT PRETTY UNIQUE.  WE’VE LEARNED ABOUT OTHER THINGS WE CAN’T LIVE WITHOUT, LIKE WATER FOR EXAMPLE, BUT UNDERSTANDING WHY GRAVITY IS SO IMPORTANT TO US COULD BE A BIT MORE COMPLICATED.

O:  GRAVITY IS A FORCE THAT ATTRACTS THINGS TO EACH OTHER.  THE MORE MASS SOMETHING HAS, THE STRONGER IT’S GRAVITATIONAL PULL.  

D:  THE EARTH HAS MORE MASS THAN MY BODY, SO THAT’S WHY THE GRAVITATIONAL PULL OF THE EARTH PULLS ME TOWARDS THE CENTER OF THE EARTH AND KEEPS ME FROM FLOATING AWAY.

O:  WHAT IS MASS?  IS IT DIFFERENT THAN WEIGHT?

D:  IT IS DIFFERENT THAN WEIGHT, AND I’LL TELL YOU HOW.  MASS IS DETERMINED BY HOW MANY ATOMS SOMETHING HAS, WHAT THE DENSITY OF THOSE ATOMS IS, AND THE TYPE OF ATOMS IT HAS.  GENERALLY SPEAKING, THINGS THAT ARE BIG HAVE MORE MASS AND THINGS THAT ARE SMALL HAVE LESS MASS.  

O:  THERE ARE EXCEPTIONS THOUGH.  A BASEBALL WOULD HAVE MORE MASS THAN A BALLOON, EVEN THOUGH A BALLOON IS BIGGER THAN A BASEBALL.  

D:  HAVE YOU EVER HEARD SOMETHING BIG DESCRIBED AS BEING MASSIVE?  WELL, THE WORD MASSIVE COMES FROM MASS.  IT IS USED TO DESCRIBE SOMETHING THAT HAS LOTS OF MASS.  THE EARTH IS WAY BIGGER THAN ME, SO IT HAS A STRONGER GRAVITATIONAL PULL THAN I DO, SO THAT’S WHY IT HAS AN INVISIBLE PULL ON MY BODY THAT KEEPS ME FROM FLOATING AWAY.      

O:  WEIGHT IS SIMILAR TO MASS, BUT GRAVITY IS ADDED TO THE EQUATION WHEN YOU CONSIDER WEIGHT.  THAT IS WHY I WEIGH MORE HERE ON EARTH THAN I WOULD WEIGH ON MARS OR ON THE MOON, BECAUSE MARS AND THE MOON HAVE LESS MASS THAN EARTH, SO THEY HAVE A WEAKER GRAVITATIONAL PULL.

D:  THAT ALSO MEANS THAT YOUR MASS WOULD NEVER CHANGE, NO MATTER WHAT PLANET YOU WERE ON.  MASS IS A CONSTANT.  WEIGHT IS NOT A CONSTANT.  YOUR WEIGHT WILL CHANGE DEPENDING ON THE FORCE OF GRAVITY ON YOUR BODY.  

O:  SO, TO SUMMARIZE THIS ALL UP, MY MASS WOULD NEVER CHANGE, NO MATTER WHERE I AM IN THE UNIVERSE, BUT MY WEIGHT COULD CHANGE.  IT WOULD GO UP IF I WAS SOMEWHERE WITH HIGHER GRAVITY, AND IT WOULD GO DOWN IN PLACES WITH LOWER GRAVITY.

D:  THAT’S ABSOLUTELY RIGHT.  THERE IS ANOTHER IMPORTANT THING WE SHOULD MENTION ABOUT GRAVITY.  IT GETS STRONGER THE CLOSER TWO OBJECTS ARE TO EACH OTHER.

O:  FOR EXAMPLE, THE SUN HAS MORE GRAVITY THAN EARTH BECAUSE THE SUN HAS MORE MASS THAN EARTH.  BUT THERE IS A GOOD REASON WHY OUR BODIES AREN’T ATTRACTED TO THE SUN’S GRAVITATIONAL PULL.  IT’S BECAUSE OUR BODIES ARE CLOSER TO THE CENTER OF EARTH THAN THE CENTER OF THE SUN.

D:  THE SUN IS SO FAR AWAY, ABOUT 92 MILLION MILES AWAY, THAT EVEN THOUGH IT HAS A STRONGER GRAVITATIONAL PULL THAN EARTH, WE ARE STILL PULLED IN BY EARTH’S GRAVITATIONAL PULL.  AND, THAT’S A GOOD THING.  THINGS ARE A BIT MORE COMFORTABLE FOR HUMANS HERE ON EARTH THAN THEY WOULD BE ON THE SUN.  

O:  IF GRAVITY IS INVISIBLE, HOW DID ANYONE EVER REALIZE THAT IT EXISTED?

D:  FOR A LONG TIME, SCIENTISTS FIGURED THERE MUST BE SOMETHING THAT WAS KEEPING US FROM JUST FLOATING INTO SPACE.  ONE OF THE FIRST SCIENTISTS TO MAKE A BIG DISCOVERY REGARDING GRAVITY WAS GALILEO.  IN THE 1500’S, HE NOTICED THAT ALL OBJECTS, NO MATTER HOW BIG OR SMALL, WILL FALL AT THE SAME RATE OF ACCELERATION.  

O:  THAT JUST MEANS THAT, IF YOU DROP 2 OBJECTS FROM THE SAME HEIGHT, THEY WILL FALL TO THE GROUND AT THE SAME SPEED.

D:  THINK ABOUT HOW CRAZY THAT IS.  IF I WAS STANDING ON TOP OF A TALL BUILDING, AND I TOLD YOU THAT I WAS ABOUT TO DROP TWO OBJECTS FROM THE ROOF AT THE SAME TIME, A BOOK AND A PIANO, WHICH ONE DO YOU THINK WOULD FALL TO THE GROUND FIRST?

O:  DEFINITELY THE PIANO.  IT’S SO MUCH HEAVIER THAN A BOOK.  

D:  I WOULD HAVE THOUGHT THE EXACT SAME THING, BUT GUESS WHAT?  THEY WILL FALL AT THE SAME RATE.  IF THERE WAS NO AIR TO IMPACT THE FALL OF THE TWO OBJECTS, THEY WOULD REACH THE GROUND AT THE EXACT SAME TIME, NO MATTER HOW HEAVY OR LIGHT THEY ARE.  

O:  ON EARTH, THE RATE OF ACCELERATION FOR A FALLING OBJECT IS 32 FEET PER SECOND PER SECOND.

D:  THAT SOUNDS CONFUSING, BUT IT’S A LITTLE LESS CONFUSING THAN IT SOUNDS.  IT JUST MEANS THAT ANY OBJECT, NO MATTER THE SIZE OR WEIGHT, WILL BE FALLING AT A RATE OF 32 FEET PER SECOND AFTER ONE SECOND, THEN 64 FEET PER SECOND AFTER 2 SECONDS, AND SO ON.

O:  IN THE 1600’S, ANOTHER SCIENTIST BY THE NAME OF ISAAC NEWTON, HAD SOME THOUGHTS ON GRAVITY WHEN HE SAW AN APPLE FALL FROM A TREE.  HE WONDERED WHY THE APPLE FELL STRAIGHT DOWN TO THE GROUND, INSTEAD OF GOING TO THE SIDE, OR EVEN UP INTO THE SKY.    

D:  IN THE YEAR 1687, HE PUBLISHED A BOOK THAT HAD SOMETHING CALLED NEWTON’S LAW OF UNIVERSAL GRAVITATION IN IT.  IT SAYS THAT “EVERY PARTICLE ATTRACTS EVERY OTHER PARTICLE IN THE UNIVERSE WITH A FORCE THAT IS DIRECTLY PROPORTIONAL TO THE PRODUCT OF THEIR MASSES, AND INVERSELY PROPORTIONAL TO THE DISTANCE BETWEEN THEIR CENTERS.”

O:  AND THAT’S JUST A FANCY WAY OF SAYING THINGS WE ALREADY LEARNED.  FIRST, ALL OBJECTS ON EARTH HAVE A GRAVITATIONAL PULL, AND THAT PULL GETS BIGGER THE MORE MASS AN OBJECT HAS.  AND SECOND, THE GRAVITATIONAL PULL GETS STRONGER THE CLOSER TWO OBJECTS ARE TO EACH OTHER. 

D:  DO YOU WONDER WHAT HAS THE BIGGEST GRAVITATIONAL PULL IN THE ENTIRE UNIVERSE?  WELL, IT’S BLACK HOLES!

O:  BLACK HOLES HAVE SUCH STRONG GRAVITATIONAL PULLS THAT NOTHING, NOT EVEN LIGHT, CAN ESCAPE IT’S GRAVITATIONAL PULL.

D:  THANKFULLY, EARTH IS NOWHERE CLOSE TO ANY BLACK HOLES.  

O:  YOU WANT TO HEAR SOMETHING CRAZY ABOUT GRAVITY?  IT MAKES US SHRINK THROUGHOUT THE DAY.  THAT’S RIGHT.  GRAVITY KIND OF SQUISHES OUR SPINES DOWN DURING THE DAY.  THIS CAN CAUSE US TO SHRINK BY AS MUCH AS A HALF AN INCH THROUGHOUT THE DAY.  AT NIGHT, WHEN WE GO TO BED, OUR SPINES STRETCH BACK OUT.   

D:  YOU CAN EVEN EXPERIMENT BY MEASURING YOUR HEIGHT FIRST THING IN THE MORNING AND THEN LAST THING BEFORE BED.  YOU MAY NOTICE THAT YOU ARE SLIGHTLY SHORTER AT THE END OF THE DAY.  THAT’S SO INTERESTING.  

O:  HERE’S ANOTHER FUN FACT.  FISH USE GRAVITY TO FIGURE OUT WHICH WAY IS UP AND WHICH WAY IS DOWN.

D:  BONY FISH HAVE SOME CALCIUM CARBONATE IN THEIR HEADS CALLED “EARSTONES”.  THOSE EARSTONES FLOAT AROUND THEIR HEADS AND ARE PULLED DOWN BY GRAVITY.  THIS HELPS FISH FIGURE OUT WHICH WAY IS DOWN. 

O:  HERE’S A COOL FACT.  GRAVITY CAN BE DIFFERENT ON DIFFERENT PARTS OF THE EARTH.  

D:  AS WE LEARNED, GRAVITY IS STRONGEST THE CLOSEST TWO OBJECTS ARE TO EACH OTHER.  THAT MEANS THAT THE CLOSER YOU GET TO THE CENTER OF THE EARTH, THE STRONGER THE FORCE OF GRAVITY WILL BE PULLING DOWN ON YOUR BODY.  AS A RESULT, THE SURFACE OF THE ATLANTIC OCEAN HAS THE STRONGEST GRAVITATIONAL PULL, WHILE A MOUNTAINTOP IN PERU HAS THE WEAKEST GRAVITATIONAL PULL.  

O: THE FORCE OF GRAVITY ONLY WORKS TO PULL OBJECTS TOGETHER.  IT CAN NEVER BE USED TO FORCE OBJECTS APART.

D:  I CAN THINK OF SOMETHING ELSE THAT BRINGS OBJECTS, OR SPECIFICALLY PEOPLE, TOGETHER… THE QUESTION OF THE WEEK.    HOW MUCH WOULD A ONE HUNDRED POUND PERSON WEIGH ON MARS?

O:  IF SOMEONE WEIGHED ONE HUNDRED POUNDS ON EARTH, THEY WOULD ONLY WEIGH 38 POUNDS ON MARS.

D:  AND, IF SOMEONE WEIGHED 100 POUNDS HERE ON EARTH, THEY WOULD WEIGH 253 POUND ON OUR MOST MASSIVE PLANET, JUPITER.  WELL, THAT’S A WRAP FOR THIS WEEK’S EPISODE.

O:  202 - GRAVITY.

D:  GREAT JOB OLIVIA, AND GREAT JOB EVA (PRONOUNCED AVA) AND DANIELLA FOR A TOPIC SUGGESTION THAT DEFINITELY KEPT ALL OF US GROUNDED.  BEFORE WE WRAP THINGS UP, WE HAVE A FEW AWESOME PEOPLE TO THANK.

O:  THANK YOU TO MICHELLE FROM SIOUX FALLS, SOUTH DAKOTA FOR THE 5 STAR REVIEW.

D:  IT SAYS “I LOVE THE PODCAST.  IT IS AMAZING.  KEEP UP THE GOOD WORK.”

O:  WE ALSO WANT TO THANK OUR NEWEST PATREON SUPPORTER, LIZ B.

D:  A BIG, BIG THANKS TO LIZ FOR HELPING TO SUPPORT THE PODCAST.  IT MEANS THE WORLD TO US.  NEXT WEEK, WE ARE GOING TO STICK TO SCIENCE, AND WE ARE ALSO GOING TO STICK TO INTERNATIONAL EPISODE TOPIC SUGGESTIONS, WHEN WE WILL GET CURIOUS ABOUT DNA FOR LISTENERS IN EDMONTON, ALBERTA, CANADA AND SYDNEY, AUSTRALIA.  AS ALWAYS, THANK YOU SO MUCH FOR LISTENING AND GETTING CURIOUS WITH US.