Calculating the Gravitational Force

Answer = 126 N
045 - Calculating the Gravitational Force
In this video Paul Andersen explains why astronauts are weightless. He also explains how Newton's Universal Law of Gravitation can be used to calculate the gravitational force between objects.
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Music Attribution
Title: String Theory
Artist: Herman Jolly
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All of the images are licensed under creative commons and public domain licensing:
Evans, NASA/Apollo 17 crew; taken by either Harrison Schmitt or Ron.Deutsch: „Blue Marble“, Die Während Des Fluges von Apollo 17 Zum Mond Am 7. Dezember 1972 Entstandene Fotoaufnahme von Der Erde (in Der Zur Besseren Wiedererkennbarkeit Um 180 Grad Gedrehten Version).English: ”The Blue Marble“ Is a Famous Photograph of the Earth Taken on December 7, 1972, by the Crew of the Apollo 17 Spacecraft En Route to the Moon at a Distance of about 29,000 Kilometers (18,000 Statute Miles). It Shows Africa, Antarctica, and the Arabian Peninsula.Español: ”La Canica Azul". Imagen de La Tierra Tomada Desde El Apollo 17.Français : «La Bille Bleue» : Photo de l’Afrique, de l’Antarctique et de La Péninsule Arabique Prise En Route Pour La Lune Par Harrison Schmitt Ou Ron Evans Lors de La Mission Apollo 17 Le 7 Décembre 1972. Ce Vol a Été Le Dernier À Quitter L’orbite Terrestre, et Le Seul Au Cours Duquel Un Géologue, Harrison Schmitt, S’est Rendu Sur La lune.Italiano: Famosa Fotografia Della Terra Ripresa Il 7 Dicembre 1972 Dall’equipaggio Della Missione Apollo 17 Diretta Verso La Luna, Da Una Distanza Di circa 29.000 km.Македонски: „Сината Џамлија“ Е Позната Фотографија На Земјата Направена На 7 Декември 1972 Од Екипажот На Вселенското Летало Аполо 17 Патувајќи Кон Месечината. Сликана Е На Растојание Од 29.000 Километри, А На Неа Се Гледаат Африка, Антарктикот И Арапскиот Полуостров.Português: A Bolinha Azul É Uma Fotografia Famosa Da Terra Tirada a 7 de Dezembro de 1972 Durante a Missão Apollo 17, Quando Se Encontrava a Caminho Da Lua E a 29,000 Quilómetros Da Terra.Русский: Вид Земли С Космического Корабля Аполлон-17. 7 Декабря 1972 года.Українська: Блакитна Іграшкова Куля - Відома Фотографія Землі, Зроблена 7 Грудня 1972 Року Командою Космічного Апарату Čeština: Modrá Skleněnka Je Fotografie Planety Země, Kterou 7. Prosince 1972 Pořídila Posádka Apolla 17 Ze Vzdálenosti Zhruba 45 000 Kilometrů., December 7, 1972. www.nasa.gov/images/content/11... Alt: grin.hq.nasa.gov/ABSTRACTS/GPN... (direct link). commons.wikimedia.org/wiki/Fil....
“Gravity Force Lab.” PhET. Accessed August 25, 2014. phet.colorado.edu/en/simulatio....
Inductiveload. English: Icon for an Earth Emblem, in the Tango Icon Theme Style., December 6, 2010. Own work. commons.wikimedia.org/wiki/Fil....
“Moon.” Wikipedia, the Free Encyclopedia, August 25, 2014. en.wikipedia.org/w/index.php?t....
NASA. English: NASA Astronaut Garrett Reisman, STS-132 Mission Specialist, Takes Advantage of the Weightless Environment on the Middeck of the Earth-Orbiting Space Shuttle Atlantis to Get Creative with His Posture during Flight Day 2 Activities. Photo Credit: National Aeronautics and Space Administration, May 15, 2010. spaceflight.nasa.gov/gallery/i.... commons.wikimedia.org/wiki/Fil....
“Newton’s Law of Universal Gravitation.” Wikipedia, the Free Encyclopedia, August 25, 2014. en.wikipedia.org/w/index.php?t....

[@dtagg112]

You explained in a few minutes what my professor took an entire lecture to explain and I had to come to you to understand it. You have valuable skills in communicating these concepts, thanks so much!

[@nikhiMD]

Best teacher I've ever had

[@anujanshika533]

Hi everyone

[@ryantheroman4331]

Taking Physics via zoom has me feeling like I haven’t been to a single physics class, after four months...

[@merrickgustavo6502]

Instablaster...

[@Mrpoopy5]

Hello from 6 years in the future

[@Tio_rop]

​@@Mrpoopy5hello from 2 years in the future

[@rider2731]

Very well explained. It shows that you really know what you're talking about. Thumbs up for you teacher.

[@ravindranathhospital1362]

Your videos on calucalating gravitational force and action potential were really helpful. Thank you

[@josellecedron6540]

How did you get the 1.5×10-¹⁰N?

[@Josh034]

Seriously

[@anna9975]

These videos are the only way I make it through IB physics... Thank you so much!

[@ikleinveld]

You are literally awesome! I'm supposed to go to the best school in the Netherlands and my teachers don't even touch this..

[@totilujan]

How did you get the 1.5 x 10 -10? What operation happens between G constant and 2.25?

[@anythinwangel]

yes pls im still confused

[@dirxin]

to simply put, multiplication was used in the given (6.67)(2.25) = 15.0075 move the decimal point to the left (once) and you get 1.5 usually answers are expressed like these examples: • 1.0 • 2.5 • 7.8 and use exponents to shorten big numbers therefore, 1.5x10^-10N i suggest you look up scientific notation so you can get a better understanding :))

[@Josh034]

why did -11n turn into - 10n tho?

[@AdehOkem]

something that the spen several minutes to explain and I still couldn't comprehend and you explained it so easily ❤ 🎉

[@LoboOutdoor]

Thanks! Needed this for my astronomy class.. It's fun to do.

[@danthurineeraja]

thanks..... but had a hard time understanding the last step o0f the first problem

[@ENBAdnanMasood]

LOVED UR EXPLANATION HELPED ME A LOT

[@iamthestrongest007]

Your videos are really really good, that I even recommended my teacher to watch your videos because she was having a hard time understanding a few concepts. Really appreciate your videos... they are really helpful...

[@user-so3zf6yw4w]

Where are you from My from gordan

[@nicotandotrunz6957]

Another great video ! Thank you

[@esquiro_cody]

Thank you so much. People like you are true heroes. I'm certain that your videos are going to help me achieve my goals in my first university physics classes!

[@m1stery_who801]

wait this is university stuff? im doing a presentation about this in the 9th grade tf

[@itzzbram0708]

@@m1stery_who801 how old are you?

[@m1stery_who801]

@@itzzbram0708 curently 15

[@user-ry6nw9dj2g]

Ya

[@joshuaosifo7977]

So easy to understand I love this lesson!!!

[@sakurabdul2369]

Clear explanation!!! And awesome animation ^_^

[@unknown_4rtist797]

This video is a blessing thank you sooooo much

[@selisiaharizaj6542]

such a good explanation plz do more videos in physics so i can learn more from you 🙌🙏

[@ibrahimibbu645]

delicious explanation.......thnx a lot

[@davidbloxham5062]

Love it! So well done

[@codingwithbobby8340]

4.45 Where did the 2.25 go? and Why does the -11th power turn into -10

[@amrutvani2]

Amazing explaination !

[@Bozemanscience1]

amrutvani2 Thanks so much. I'm happy to hear that the videos are helpful.

[@terryholland2526]

I would like to find out how you got your answer. I'm new at this stuff and need a little more help than just "here figure it out."

[@meranism673]

kzbin.info/www/bejne/gIKUd2WYadZ2rc0 I believe this link will give you an idea how he achieved the answer .

[@gehadyasser1001]

Thanks so much that was so helpful

[@sebastianmosley2936]

Great Video! Thank you.

[@EmePlaysGames]

This helps me so much im glad i stumbled upon this its helping so much in my class i didn't get it now I do

[@cipherpol0123]

Very helpful thanks man 😊

[@Meatchop]

Never having studied physics in HS, this was really interesting. Ty!

[@kaylaspeakman916]

I’m doing this as a freshman in HighSchool and I don’t have a choice😭😂

[@ideologybylakshya]

Hi

[@ideologybylakshya]

Past man

[@baxyy5586]

@@kaylaspeakman916 ayyyyy me too

[@marianiazi7928]

Sir I have one question that zero work done on a body by force of gravity who it is can u proof this plz

[@johnmdc4228]

please put the complete step by step process to understand easily by other students, thank you

[@manish.shukla.31]

When two m masses meet released from a separation of 1 cm?

[@bucketrance]

Your 4 on 4:44 was amazing. what 4?

[@destiny-ry3ji]

Anonymous squirrel this comment was 4 years ago 🤯

[@cj1240]

@Alfonso Flores and ur comment is from 4 days ago...

[@thisuserhaspassedaway3100]

And I’m the fourth comment 😳

[@Hypoaqua]

Yes

[@samdoesstuff4924]

Alfonso Flores and your comment is 4 months ago

[@lizzyberg1082]

how dowe calculate the mass of one of the objects if the distance of null point,distance between two objects and mass of one of the object is given.

[@janmejaybehera491]

can u pls make equation between gravity and motion of a mass ?

[@pigeonhead9139]

this makes physics fun, thank you

[@Sergiobaruffi]

Great class congratulations

[@TheScienceCube]

Nice one!

[@Lucuskane]

Thanks so much, I wish class like this everyday. Can you add another "m" to numerator? If calculating for 3 different masses

[@hiralshah6030]

That possible?

[@abugreayingangbagerald1976]

Thank you so much,I really appreciate

[@itlogmaalat7097]

thank you so much!

[@johnmastroligulano7401]

So what your saying is you do from your "feet" not from the center of your personal mass or did you mean that when you said from where you where standing?

[@anilsharma-ev2my]

Do you give exactly calander date and time for next earthquake by using G and g

[@rakaarsha4723]

i love ur vids

[@sushilasubedi]

I have got one question. How is force inversely proportion to the square of distance.

[@pankfish]

I have only seen the Newton described as kg*m/s^2. How do we get (m/kg)^2?

[@lindelwamthethwa9528]

Thank you, understood very well

[@joshlauriruth4316]

Dude thank you so much!

[@theodoresweger4948]

I have a question using this formula and using my weight of 68KG and the suns mass 1.989e30 kg and being 150,7070E6 km from the sum I get a force of 397372.6 newtons toward the sun, and since we are going aroung the sun at tremendous speed the outward force must be equal or else we would be torn apart, am I correct? Just a thought. .. Corrections and critizems welcome...

[@SUPANIJAFRICTV]

thank sir it was really helpful

[@user-di6qb6ij9x]

can you do a video on how to calculate the ratios of distances? like discussing the inverse and proportionality of objects.

[@salvadorbuschittari6870]

But how do you take into account the volume of these objects? So far you are compressing the mass in a particle and not in an inmense volume (which might not act as depicted by the formula)

[@tembogabriels8883]

How you find the magnitude of gravitational force between two objects.given the masses and the distance between them?

[@MerlasPaul]

how you calculate the kg formula in void ?

[@moazelsawaf2000]

Really you are intelligent, Thanks a lot sir ❤

[@kulkarniaditya754]

Thanks for making gravitation easier

[@Ifinger151]

2:34 did you mean Time or Distance. I think you mean Distance because in relation to earth a human simply doesn't have the mass to stay in orbit unless moving at a unfathomable speed.. at least in my opinion of course

[@nellvincervantes3223]

I have a question? Based on the examples from the books about statics, why gravitational force is not included between two objects there? Only the weight or the gravitational forces between object and Earth are only included and not G.F. between two objects. By that case, where could Gravitational forces between two objects be applied?

[@miranahmed6741]

very helpful

[@tsegayharefe9929]

It is helpful .i love it. But always ask that what force if radius is zero or what will happen to core of the earth b/c radius is zero. What do you think ?

[@carultch]

The formula might lead you to believe that the gravitational force would be infinite, but nothing could be further from the truth. This formula is only strictly true for point masses. You can prove with Calculus that it applies for spherically symmetric masses of any size and distance as long as they are external to each other, with that last phrase being the key point. It only applies when the bodies are external to each other. If you consider something in the center of Earth, you'd have to add up the gravity due to every piece of Earth as vectors, because Earth is not a point mass. Given a spherically symmetric world, at the exact center of it, the gravitational force adds up to zero. So you would be weightless in the center of Earth.

[@GoodTime-zn1bg]

Actually in the perfect round revolution gravity is taken out, the newton intuition and explanation is half right half wrong. The force of gravity cancels out in the formula. In an elliptical revolution the condition of falling and missing fits better, but again just in the falling pathway. Isn't it?

[@caetonfath5061]

If all objects have a gravitational pull, if we add more objects/mass to the equation dose it still work. For example the mass of you + the earth+ the tree next to me + my house would it still work and make sense

[@deepthink7794]

Will we get the same answer by using w= mg

[@eilafansari5351]

5:28 I am getting the answer as 126.30N...Is it correct or wrong???

[@chelseycriswell]

I'm just confused after dividing 9 by 4 how you went from (2.25) to the answer (gravitational force) did I miss something? I'm new at this lol

[@moistbagels3420]

Chelsey Criswell multiply 2.25 with 6.67 which is approximately 15.0 but to put the number into scientific notation you need to move the decimal 1 over making the scientific notation number 1.5 x 10 to the-10 istead of the -11

[@sadale24]

I am confused about the answer. I got 1.26x10 to the 6th as my answer. wouldn't that be 1,260,000N not 126N? what am I missing?

[@meredithgordon5447]

Sierra Ok, so i know its pretty late to answer for now, but just in case I wanted to help since this has been stumping me as well. So remember the formula wheras F1=F2= G M1 x M2/ distance or radius ^ 2, you have to square the radius or distance and then divide it by the numerator's product. It seems really insignifcant but it makes all the difference. Hope you or anyone else can find help from this :3

[@StarsAreSadeem]

Thank you so much 😊

[@bananabeast9384]

ty so much, my physics teacher is horrible at teaching and should not be doing so, unlike you, your amazing! Thanks for the help!

[@khedarenperumal8906]

Nice thank you very much!

[@UWBadgersfan28]

The forces of Planet A on Planet B = the force of Planet B on Planet A (for example) due to Newton's Second Law, right? This can also be shown using the GM1M2/r^2 equation, correct? Thanks!

[@carultch]

That's Newton's third law, but yes that is correct.

[@tirthankardas3392]

nice one

[@soccerchinchilla]

At 5:28, why do we take the distance from the center of the moon to the earth's surface? Should it not be the distance to the earth's center? Thanks, and sorry in advance if I missed something.

[@chumbis222]

Because he wants to measure the gravitational force between him and the moon, and since he was standing on the moon it was to the moons surface. If he was calculating the gravitational force between him and the earth then he would have it be the center of the earth. I'm sorry if I'm not explaining this very well, I've never been very good at explaining things but I hope that helps!

[@sahand_rwandzy]

Great explanation but, that “Four” kinda got me😂

[@londiwesibahle8369]

Thank you🤗

[@stephaniecantu6973]

It would be awesome if that last problem can be worked out with out a calculator! Studying for the MCAT and didnt get 126N lol

[@Kyrqs]

I did it somehow

[@Jaami]

Thanks!

[@saintmonster5984]

thank you that helped

[@Gromitdog1]

Doesn't the force of gravity become equal to the centrifigual force as to why there is weightlessness in space?

[@HarrysDream]

can u do ap psych vids plz. i use crash course but they arent as informative as your stuff

[@seshadrishankar6827]

From my 12 year old : gravitational force is the force that attracts me to Earth and is also the force that attracts the Earth to me. So if we have a population explosion will the Earth expand?

[@farbodAprin]

Wow wonderful 😍😍😍 thanks alot...Aparin

[@priskangassa3154]

Is that 78kg the mass of somebody on the surface???

[@Firelsa200]

What about 3 objects?

[@pragnashah2354]

why we take the centre between this two objects???

[@thestewpot2590]

so did the calculation for the moon, but with my own weight. Then i used newtons second law to determine the acceleration due to gravity which came to 1.62 m/s squared. then i did the same with earth, but i got 11.15 m/s squared. Which was of course wrong because its 9.807 m/s so i was wondering if i may have done something wrong.

[@carultch]

Without knowing the facts you used, I can't help figure out where your discrepancy happened.

[@immanuvellohith1057]

really useful one thnk uuu

[@satyamchauhan9622]

Immanuvel Lohith

[@edwardmacnab354]

So what is it a Force or an Acceleration ?

[@AuroraDarkStar]

If you were to make a spherical hole at the centre of the Earth and put yourself dead centre, with the distance between two masses being zero does that mean the gravitational force is infinite? Very helpful vid, thanks!

[@jejjiz6162]

AuroraDarkStar That is an interesting question. However, you cannot say that something divided by zero is infinite (I thought that too, and had a long discussion with my maths teacher about it). Maybe you can calculate it using the limit of the formula as v approaches 0?

[@Vegas702EsLV]

so would gravity be an element?. what if you dont want to kno force of gravity?. what would gravity be?

[@aswinaadhav3204]

What how 1.5 came can anyone explain that? Plz

[@lizzlasagna]

how did he get 1.5?

[@jaimontillana7661]

How to compute the force between you and the moon?

[@jabin1997]

Thank you so much! I wish you were my teacher at school, lol :))

[@Bozemanscience1]

Jabin Stalin I am your teacher in a roundabout way. Welcome to class. :)

[@alessandromariani3015]

I don't understand why the force of attraction is equal, then if the earth and the moon were stationary the gravity should move the two objects at the same speed right? That's strange

[@philvinet4145]

IN you example of you standing on the moon...you used just the R value for the moon. Why did you not use the R value for yourself? (yes I know the difference is very small but correct is correct. )

[@mr.unknown1070]

Awesome. All doubts cleared!!! We dont have such brilliant teachers in India and that's why Indian educational system is nothing when compared to America's and other countries.

[@gemmablac7290]

Is this correct = 1.26*10^-2

[@anmekazaki5185]

i don't undestand the part where you do 1.5X10 (-10)N

[@jackgao5681]

what if not all objects fall to earth at 9.8m/s, but close since the objects' gravity is too minuscule to alter the speed.

[@ashleymora1430]

THANK YOU