Newton's Law of Universal Gravitation

[@reyyanmansoor5164]

Physics Jesus here to save my grades

[@masarratrashid1617]

@Eddie Hendrix hold up

[@logan2906]

@Eddie Hendrix kind of a dick move. FYI I know he’s a bot

[@projoefn6080]

@@logan2906 who is eddie hendrix

[@skitzyfizz]

@@projoefn6080 your mom

[@Patrick-Messi10]

Definitely brother

[@vikramtete7461]

Thank u Dave for ur elegant explanation. And could u just check my understanding regarding hypothesis and postulate that I have mentioned below: While having a scientific method of studying on microscopic phenomena(atomic theory), at first, scientists make some postulates(assumptions) on atomic theory. Then next, they make hypotheses on the postulates they have made on atomic theory. The hypothesis is like "If these are our assumptions(or postulates) on atom then this will be the possible consequences". After that they test the hypothesis through experiments. If the hypothesis fails the experiment, they will change or modify their postulates to form a better hypothesis. At last if the hypotheses pass the experiment, the hypotheses will be accepted and will be considered as a theory as long as there is no evidence or experiment to conflict or contradict the hypotheses. Is this how a postulate and a hypothesis related to each other in scientific method of studying microscopic phenomena or phenomena beyond reality (like space-time curvature)? Please do reply whether my understanding is right or wrong. Thanks.

[@ProfessorDaveExplains]

not bad! check out my clip called "Why you should never say it's just a theory" in my science for common folks playlist for more info on the scientific method!

[@very..angry..man..]

Can not wait for the comments. I've recently had a intracranial and subaracnoid bleeds and would be lost without dave have been struggling a bit. Thanks kid. Going through a lot of your stuff.

[@jsbllrt]

Cheers from Argentina, Prof. Dave! You are an awesome educator!

[@volthedudde7157]

Newton said in the original explaination of the Newton's law of universal gravitation, he was describing the apple falling, then he just shorten the description to the apple fell on his head

[@konglink3359]

Could u make a video explaining how the gravitational constant was calculated

[@bushral.tasneem5464]

I just stumbled upon this video today because of an essay I had to write on gravity. I couldn’t understand anything in my textbook or even in other KZbin vids, until I came across this one:D I’ll watch it a few more times to understand everything more clearly, but thanks so much for making videos like this!

[@sifugurusensei]

The force is strong in this one

[@hamster166]

Haha nice one!

[@prashantbhatt2864]

Sir can u make chapter playlist according to classes it's hard to find consecutive topic video one after another .

[@justtfor4fun]

pray for me i need to pass my test

[@adeonafowokan2613]

me too😢

[@Mt.Trashmore]

Kind of confused by the question at the end, shouldn't the radius be 2.5 as they are standing 5 meter apart making 5 meters the diameter? or does "r" stand for distance between the bodies?

[@ProfessorDaveExplains]

ah yes i see the confusion! in the context of a circle, r stands for radius which is half the diameter, but in this context r just describes a distance between two objects.

[@eColeOnline]

Hello, what is the software you use to make your animations and presentations? thank you

[@ProfessorDaveExplains]

adobe after effects

[@titidechdamrongwut1351]

Professor, Great VDO I like it. But question when I think about black hole!! We knew it was a massive star before become a black hole. If we think about Newton formula, it should have the save gravity force for both before and after become black hole, right? since the mass of star remain the same. (in fact, black hole will loss some mass when released energy). Why so many people think black hole will have more gravity force than star? If the formula is correct, both black hole and star should have the same gravity force, isn't it? Can you confirm my understanding?

[@ProfessorDaveExplains]

well, you're correct that if a star dies and forms a black hole, it will have the same mass as when it was a star, but this mass will be crushed into a point, and remember that gravitational force is inversely proportional to the square of the radius. so if you were at the edge of a star and stayed right where you are as it died and formed a black hole, the force of gravity felt would be the same, but as you move closer to the black hole, the gravitational force becomes incredibly huge! more on this in my upcoming astronomy/astrophysics course!

[@titidechdamrongwut1351]

Hey professor, I'm glad to hear your new course! and looking forward to see it. Thank you for your explanation anyways.

[@sunitaraniggpsbhangu1482]

Gud explanation

[@geenapaulson638]

He had to discoverd the calculus to do so 3:53

[@ADNZ5442]

How do you write into the calculator -11 and times it. It comes out as 0 for me. Can you help?

[@좋은꿈̮-w2i]

11×11=121

[@carultch]

Let me know the specific make/model of your calculator, and I can tell you. There is often a button with a capital E on it, that allows you to implement 6.67E-11 as a shorthand for 6.67*10^(-11).

[@zack_120]

2:58 - is there proof why it is r^2 but not r^1.9 or r^2.1?

[@tgstudio85]

Are you fcking serious?

[@sanjaysunil911]

Your theme song is awesome sir

[@kollichiranjeevi5736]

Now itself i watched the video fr the first timeee.... It is useful sirrr... I liked ittt..nd i hope ur service continuesss... Waiting fr more tutorials...

[@Asalashjari]

"he had to invent calculus to do that" oh dear.........

[@marla8041]

at 6:17 i have a question. so the radius between the COMs of the objects are still relevant. so. if something is light and really really close to the earth, would the acceleration be just slightly higher? and the inverse? (obv it'd be negligible, but still?)

[@ProfessorDaveExplains]

well acceleration due to gravity doesn't depend on the mass of the object, but yes it depends on distance, so the acceleration gets smaller as we move away from the earth. for example in low earth orbit acceleration due to gravity is around 9.0 rather than 9.8.

[@carultch]

The Cavendish constant named G Times the product of Mass A and B All over the square Of the distance they share Gives the force of our friend gravity

[@padmalathaumesh5590]

Very well explained relating the content so well, tku

[@korleparanarendra9345]

He is expert in teaching any subject in the world 😀

[@lordchinchin4220]

is that music 7:24 played in lifts?

[@llawliet3656]

Yes

[@benmcreynolds8581]

There are scales in our universe that are so immense, it's understandable if we can barely grasp them. What if at those immense scales, we don't yet fully grasp how density, mass, Electromagnetism, static charges, temperature, pressure, radiation, velocity, etc. behave on VAST scales throughout our cosmos? I hope we continuously improve our understanding over time because it would be foolish to think we fully understand these things. Especially gravity. I'm talking like the scales of galactic filaments, multiple galaxies interacting, and many more cosmic bodies & structures. We are getting better & better but some things are just so vast it's understandable we don't yet fully grasp them yet. I'm curious to see where things go as we advance our ability to study these things.

[@sunitaraniggpsbhangu1482]

Can u make full ch on gravitation pl

[@brandonhacksandtrainers9246]

Hello Professor just to clarify.. the acceleration of fall of a heavy and a light object doesn't depend on the mass because of inertia... but still the heavier object will hit the ground after the lighter object because of wind resistance ? correct me if I am wrong... And thank you for this amazing playlist which doesn't let me sleep at night... :p :)

[@ProfessorDaveExplains]

Correct, the mass of the object is not a factor. For wind resistance it's about the shape and composition and other factors, whatever determines the amount of friction with the air, so that aspect is also not about mass. You could drop a piece of paper and a paperclip with the same mass and see the huge difference because of the much greater surface area of the paper that produces more friction.

[@brandonhacksandtrainers9246]

@@ProfessorDaveExplains you are just amazing.. pls never stop making videos... as soon as I get my visa card I will definitely support you on patreon..

[@janajusimi269]

How did Newton make the formula for gravity using the gravitational constant that wasn't known until 100 years later

[@marcg1686]

Newton theorised that the force of gravity was proportional to the product of two masses and inversely proportional to the distance separating them. He needed a constant to come up with an equation. He had ∝, he needed =.

[@betaorionis2164]

He couldn't know the exact figure of the gravitational pull, but he knew that if one of the masses doubled, the pull doubled and if the distance doubled, the pull was divided by four. However (and this is only my own guess), I imagine he could approximate it and know at least its order of magnitude, following this method: F=G*M*m/(d^2). But if we are on the surface of planet Earth, then G*M/(d^2) = g = 9.8 m/s^2, so G = g*(d^2)/M, where: g had already been approximated by Galileo and its value had most probably been refined in Newton's time. d (the radius of the Earth) was known since the time of Eratosthenes and in Newton's time, navigation around the world had perfectly adjusted its value. M (the mass of the earth) is equal to the volume of the Earth multiplied by its average density. The volume was known because the radius of the Earth was known. The average density is trickier, but the most straightforward calculation is to use the density of stones, say between 3000 kg/m^3 and 8000 kg/m^3. So, Newton could at least have had an approximative idea of the value of G.

[@CyprianChikondeMwila]

Job well done professor. From ZAMBIA💪🇿🇲🇿🇲🇿🇲

[@julianmoody5939]

ive been watching your flat earth videos and debates for a while, and my teacher just assigned me on of your videos to take notes on!! im so excited!! your explanations of topics are incredible and easy to understand!

[@ivoryas1696]

Julian Moody Lmao, I wasn't shown this in class but I came here from those videos two then subbed.

[@colorx6030]

Ohh, interesting. I'm more excited for Modern Physics now since I can see there how Einstein further explained what is gravity. While watching this video, I was really curious as to why objects exert gravity on other objects, albeit by a negligibly small amount.

[@bookdream]

Anyone else feel like the algebraic manipulation at 6:00 is completely arbitrary? Why does "m" have to be the mass of the object and not earth?

[@ProfessorDaveExplains]

it can be either, the force the object and the earth impart on each other is equal

[@multymind4744]

Very informative content sir... Lets assume some situation: i) now you are steadily standing in some place with ur feet touching the earth's surface due to the so called gravity, ii) in sphericl earth model some other person is standing like you in just below the earth's surface opposite to ur position i.e exacy opposite side of the land mass, iii) he seems handing upside down from ur point of view and vice-versa, iv) now you are standing in the same place like before. There is a big hole near ur feat. If any object, for example if a ball comes in the upward direction from that hole against the so called gravity, according to ur view it is impossible, it breaks the law of physics. The same applies to the another person who is standing in the other side of the earth surface, iv) let the hole be created near ur feat and inserting a pipeline and continued till the other end (12,756 km diameter of earth) and another hole be created from there. From ur view the pipe is going downwards, but while it reaches the other end its emerging outwards from the surface, its weired, v) now u r dropping a ball into that pipeline below ur feet and the other person also doing the same. Now what happens! The ball from ur side travels to the other end and emerges from the ground and rises up to the other guy? After that what happens? How far will it go upwards? Will it fall back? If it happens what that means? From ur point we assumed it in (ii). Will the ball from other side reaches you. Plz dont say we cant build a tunnel like that, it is impossible, earth's core temperature will not allow it, gravity will act till the middle of the earth abd after that ball be crushed.. The above are fully assumptions. Waiting for ur reply sir...

[@tgstudio85]

*iv) now you are standing in the same place like before. There is a big hole near ur feat. If any object, for example if a ball comes in the upward direction from that hole against the so called gravity, according to ur view it is impossible, it breaks the law of physics. The same applies to the another person who is standing in the other side of the earth surface,* Which law of physics it brakes kiddo?

[@juniebellim3820]

Why -8 exponent is the answer?

[@draganjonceski2639]

Well G has a tiny value of 6.67×10^-11 so ofcourse if you multiply small masses like 2 people with it you are gonna get a small value like 1.8×10^-8

[@reyyanmansoor5164]

@@draganjonceski2639 my guy that wasn't the question.

[@math4fun]

Well explained. I'm trying to verify the value in gauss of the gravitational field of an object isolated (without another as referential), my guess is g=W/tan(60) where W is the wheight force (calculated through the product between friction/mass/acceleration) devided by the tangent of the angle formed between two tangents of the center of mass( crossing the vectors of the wheight and normal forces, friction and tension forces vectors). If you cast a solid object in space the object will rotate in two principal axis (axis A (left) and B (right)) this rotation will amplify the gravitational field of the object. On earth is possible to calculate the field of an object in equilibrium by quotient between the wheight force and the tangent of the angle formed amongst these axis. This conjecture agrees with the Feymann's diagramm, these axis represent coherent states of the gravitron wich amplifies the field of the object.

[@aidanwalsh9234]

you lost me when you said “my guess is…” 😂

[@huseyinkagantoy5469]

The situation caused by gravity, the weakest force in the universe. where gravitational interaction makes its presence felt on the largest scale are galactic superclusters; Beyond this point, the gravitational effect disappears and as a result, all structures in the universe move away from each other due to the expansion of the universe. #gravitational #interaction #gravitation

[@MarkiplierOfficial]

Doesn’t he contradict himself when he says that an objects mass does not affect its rate of free fall, and then brings up F=ma which shows a direct correlation between the two?

[@ProfessorDaveExplains]

I literally proved it mathematically. Please watch again and pay closer attention.

[@tims5268]

@@ProfessorDaveExplains Would gravity be 0 at the centre of the Earth because there would be almost identical mass in every direction?

[@throwawayavclubber7269]

@@tims5268 Correct. In fact, that is Newton's Shell Theorem.

[@steamlover9274]

Hello there I have a question regarding this concept what happen if distance between two objects will become infinity I put the values into the formula Fg = G × m1 × m2 / r2 so the value of r2 will become infinity ♾ any number divided by infinity will become zero that means Fg = 0 N but as i know gravitation force will never become zero as it tends to zero but never zero I am confused so much with this problem please conclude my problem

[@carultch]

Essentially, two objects that are infinitely far apart, are gravitationally indifferent to each other. In practice, no two objects are ever infinitely far apart, but they can be far enough away that the gravity between them is insignificant that it doesn't matter. For instance, the gravity of our nearest non-sun star has very little effect on our planet, because our sun's gravity dwarfs it. Also, the sun, Earth, and entire solar system are also both accelerating together, based on the gravity of other stars in our immediate neighborhood of the galaxy, so it appears that there's no difference in relative acceleration among the planets in the solar system, due to distant stars.

[@peace7784]

Very elegant. Thank you!

[@aikareign1714]

Hi! Could you explain how you got the answer on the comprehension? I hope I'm not being a bother, but I just can't really understand it😅

awesome video!

[@BraydenSchultz]

your getting me through duel credit physics rn thanks so much

[@shreyasingh8498]

Sir gravitation depends on the oxygen or not

[@ProfessorDaveExplains]

nope

[@alexfanofspiders1796]

so. im writing physics in 2 days and im just watching ur vids to study. thanx man. you make it a lot easier.

[@preciouskarlaloares5055]

I understood ur lesson prof, just the problem is that, I got the incorrect answer for the question for comprehension. I got 4.20200 x 10 raised to the negative power of 10

[@Ray2311us]

2:35 Negligible? Quantum mechanics says: Hi

[@Ray2311us]

Also the Compound effect says: Hi

[@huotui]

Hey there, in many description of gravity, they use a trampoline with a heavy objects in the middle and small objects falling towards the center. In space there is no 2D trampoline and I can't quite extrapolate that demonstration into 3D space...can u explain it to a non scientific brain?

[@carultch]

It is just a representation. Obviously, space isn't 2-dimensional, but we are limited to showing a 2-dimensional model in a 3-dimensional space, because we live in a 3-dimensional universe. The idea is that spacetime itself is the 4-dimensional counterpart of the 2-dimensional trampoline, and it is curved into a dimension we can't access, that causes the "straight line" paths through curved space-time, to appear as curved paths from our point of view.

[@kyleissa7667]

How do i find m1?

[@athunderbolth9646]

Why didnt the idea of gravity strike Newton when he was taking a shit (on the toilet bowl) rather than a nap under the apple tree? Na na ….just askin

[@carultch]

Because it's not a historically accurate legend. This is something people made up after his death, that it was an apple that fell and hit him in the head, and gave him the epiphany. He did have an apple orchard, and he did go out and sit in the apple orchard while contemplating the problems he was working on, so there's a kernel of truth to this story. But the idea that an apple hit him in the head to make him have this realization isn't an event he ever claimed happened.

[@kristelanntutor45]

What would happen to the force of gravity between two objects if their separation distance is reduced thricefold?

[@KRATOS-dq6sd]

The force will be 9times stronger ( as it F is inversely proportional to the square of the distance)

[@QuérenKubwarugira]

3:56 had me on the floor

[@2002southzone]

He reminds me of James Schrader, the Dr. Squatch Soap guy, if Schrader could explain physics.

[@Sunnyv3_the_g]

Bro this is amazing

[@siobhainb5891]

Thank you!

[@abdifatahbudul8467]

this video change my point about physics maths or chemistry❤️ well explained thanks👍

[@khalidrahmath]

You just made my head spin like earth

[@katlehomotseare8111]

Albert Einstein is my man🤯

[@ghoroob19]

Sir isaac Newton was historical genius

[@EddieTehBoss]

Why is r squared in the equation?

[@ProfessorDaveExplains]

that's just how gravity operates apparently, i'm not sure if physicists could answer on a deeper level

[@lonemuhaibtutorial.7639]

@@ProfessorDaveExplains Then how can you square the radius if you don't know why is this squared..🤔🤔🤔🙆🙆🙆🤒🤒🤒

[@ProfessorDaveExplains]

Um, you just do. It's arithmetic.

[@lonemuhaibtutorial.7639]

@@ProfessorDaveExplains Sir if it is arthimitic then why don't you explain it in one of your videos..🤔🤔🤔

[@ProfessorDaveExplains]

I have an entire mathematics playlist.

[@MediocreApologist]

Well done !

[@chaospsycho8263]

Thanks Sir you are the best

[@SIMEONOVVASIL]

how it's determined the centre of the masses (Earth and Moon)? Why the moon is orbiting the Earth, is it because it is falling towards the Earth? If yes, why then the moon is moving away from Earth at a rate of 1.6 inches (4 cm) per year? If you have ready answers in your videos, please share the links, thanks!

[@ProfessorDaveExplains]

Yes the slow recession of the moon is very fascinating! It is a complicated tidal effect, I can't describe it in detail. Just google it, you'll find a bunch of stuff.

[@kfresht2641]

The Apple should of never fell on newtons head

[@thekiwithatplays]

it didnt

[@hdevillier5119]

Potentially dumb question here: Does it matter if you use F=G(Mm)/r² or F=(GMm)/r² ? Are they both technically the same?

[@ProfessorDaveExplains]

Yep algebraically identical!

[@hdevillier5119]

@@ProfessorDaveExplains cool, thanks!

[@mahbubrashid2935]

Newton died on this day(March 20 ,1727)..... Professor, Can you make a tribute video for this greatest inventor (focusing on all the scientific inventions made by him)?

[@ProfessorDaveExplains]

ooh, or a whole series with biographies of famous scientists! not a bad idea!

[@mahbubrashid2935]

Exactly! Another request then, please make sure you put Nikola Tesla in those.... People kind of overlook this genius

[@ProfessorDaveExplains]

oh i would never overlook Tesla! he's the man.

[@sunitaraniggpsbhangu1482]

Don't forget sir Galileo☺

[@sunitaraniggpsbhangu1482]

Can u make full ch on gravitation pl

[@australianjuniorscience9672]

Professor Dave grohl

[@anitachaudhary3164]

Thanks man very much

[@farahfara8898]

Thank you from Morocco 🇲🇦😂

[@lavieh3drelaxmelody773]

Good teacher

[@donteatmymochi7675]

I am new here and the intro tho😂🤣😂🤣😂🤣 caught my attention,

[@hrittikchy3619]

I am from Bangladesh....i love physics very much...Thank you very much for this vedio....we can say this law g/wm

[@SIMEONOVVASIL]

It's a tiny force (from comprehension), but isn't it also because of huge the gravitational force from the Earth?

[@Zain0_0]

4:00 that animation is poor and inaccurate, it shows the earth and the moon are tidally locked to each other which is wrong.

[@ProfessorDaveExplains]

The moon is indeed tidally locked to the Earth.

[@animmensah666]

Do you think that the gravity will not work properly. It will work better for it harbour and the gravity

[@ProfessorDaveExplains]

Um, what?

[@sH-ed5yf]

Newton and me got hit by an apple. Newton: now famous in the whole world and an legend of science. Me: got a big scare and felt uncouncues for several minutes.

[@tperingode1]

proffessor is th e gravitational value 6.67*10 to-11 or 9.8

[@ProfessorDaveExplains]

the first one is the gravitational constant G that is used in newton's law of universal gravitation, the second is the acceleration due to gravity on earth. different constants!

[@tperingode1]

thanks....professor, I loves your classes

[@mokshitmehtatutorials-conc4423]

excellent

[@orthodoxtewahedo1962]

I am understand you teaching

[@vfxjmb]

bro invented physics and calculus

[@AbrarManzoor]

love your content dave….especially your math course its helpful...Thank you God bless you

[@rtrj1087]

I've just realized that it's easier in English than my own language 😵

[@SIMEONOVVASIL]

Why the moon not orbiting the Sun, but orbiting the Earth when we know the sun has enormous mass compared with Earth's? Something missing in my understandings =), if you can help!?

[@ProfessorDaveExplains]

So as I show in this video, the gravitational force drops off by the square of the distance, which means the effect of gravity gets much, much weaker as things get farther away. So you are correct that sun is way bigger than the earth, but it is also extremely far away, while the moon is very close to us, relatively speaking. So it orbits the earth as the earth orbits the sun.

[@ProfessorDaveExplains]

Technically it's only orbiting the earth.

[@rkreike]

Q: If the sun would stop rotating, then why don’t the planets fall into the sun?

[@ProfessorDaveExplains]

Hmm, I think a better question is why would they?

[@JK-0423]

No way I like the problem at the end!!

[@comradejohn8593]

Thank you Science Jesus👏

[@shahzeenakazi2970]

The apple is close to the earth and moon is much away as force is inversely proportional to the square of separation so the gravitational force on apple should be greater but why it doesnot happen?

[@ProfessorDaveExplains]

it also depends on the mass of the objects.

[@shahzeenakazi2970]

Great! thanks 👍

[@wizard1404]

sundial is only possible on a flat earth. They have lied to us.n

[@throwawayavclubber7269]

lol @@wizard1404

[@CS_Lewis]

thanks.....i dont understand anything anyway🤣🤣🤣

[@koralizzz]

Finals week or my final week?

[@henrymendes3906]

who else is here because of school

[@noursvsp_]

I am- my teacher assigned this to watch so I can know how to solve an assessment🥲✋

[@nafey_nice]

Watching this video third time today.. there's something i don't understand but idk what it is.. maybe the fact that if the apple's mass is greater than the earth's, the earth would fall on the apple :p Professor can you answer these questions please.. 1) Just for confirmation, if the velocity vector of satellite becomes zero then it will fall to earth.. right? 2) what will be the case for satellite to stop moving in circular motion and travel in a linear path? Just an advice :) since I am not an English speaker I would advice you to not stop using heavy english words like "dismay".. I had to google its meaning lol :p Love from Pakistan :)

[@ProfessorDaveExplains]

1) Yep, if the satellite lost its tangential velocity, it would fall to the earth. 2) To travel in a linear path it would have to escape earth's gravity, so I suppose it would just have to go even faster such that it would continue in a straight line rather than being stuck in orbit.

[@nafey_nice]

@@ProfessorDaveExplains wow Professor you answered really quickly .. Thank you very much :)

[@Mike_is_COOOOOOOOLLL_ONG]

the hair goes crazy on god

[@sandhyasharma6575]

Hey apple had falled aside to him not in his head

[@sandhyasharma6575]

Sorry fell

[@benquinney2]

Barycenter

[@shreeparkash6648]

Nice shirt

[@bereketaklilu8247]

yo did this guy finally showered

[@evonmakonza3934]

I've been saved😥😓😭😢

[@boofang10]

FANTASTIC & SIMPLE way in explaining !! TQ Prof Dave !! :)

[@KINGERTADC_yay]

Very nice video this has helped me with my AP physics C mechanics keep on the great work!

[@techedbassoon]

Did u pass w a 5?

[@abelassefa2413]

I steel need to know how any object exert gravitational force

[@carultch]

I aluminum need to know how any object exert gravitational force.

[@joshualipovetsky2744]

Thank you, Dave!