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Jan 13, 2026
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Understanding Newton’s Law of Universal Gravitation
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Newton's Law of Universal Gravitation
Ever wonder why planets don't just fly off into space? The answer lies in gravity! When observing Earth's orbit around the Sun, we can see that Earth's velocity is constantly changing direction due to the gravitational force pulling it toward the Sun.
This same force of gravity acts on both objects - Earth pulls on the Sun just as the Sun pulls on Earth. Without gravity, Earth would travel in a straight line through space instead of its circular orbit.
Newton developed his understanding of gravity through his three laws of motion. His first law tells us objects in motion stay in motion unless acted upon by a force. The second law shows that acceleration requires force. The third law reveals that forces come in equal but opposite pairs.
Quick Insight: When an apple falls from a tree, it's not just Earth pulling on the apple - the apple is also pulling on Earth! The difference in their movements is due to their vastly different masses.
How Gravity Changes
If the Moon weren't affected by Earth's gravity, it would travel in a straight line through space rather than orbiting us. The gravitational relationship between objects depends on both mass and distance.
Newton's big discovery wasn't gravity itself but its universal nature. Everything with mass attracts everything else with mass - from planets and stars to you and your textbooks.
When the mass of an object doubles, the gravitational force doubles too. If both objects double in mass, the force increases by a factor of 4. But distance works differently - if the distance between objects is cut in half, the gravitational force becomes 4 times stronger!
Remember This: Gravity follows an inverse square relationship with distance. This means that doubling the distance makes the force 1/4 as strong, while tripling the distance makes it 1/9 as strong.
The Universal Gravitation Formula
Newton's Law of Universal Gravitation can be written as: F = G
This formula has several parts:
- G is the gravitational constant
- M₁ and M₂ are the masses of the two objects
- r is the distance between the centers of the objects
When you change values in this formula, the gravitational force changes predictably. If you triple the mass of one object, the force triples. But if you triple the distance between objects, the force becomes 1/9 of its original value.
Try This: Notice how the formula shows that gravity never completely disappears - it just gets weaker with distance. Even objects across the universe exert tiny gravitational pulls on each other!
Gravity and Weight on Earth
Your weight is actually the force of gravity acting on you! On Earth, we can calculate weight using the simple formula Fg = mg, where g equals 9.8 m/s².
This simplified equation comes from Newton's Universal Gravitation formula. When we apply it to Earth:
- Fg = G
- mg = G
- g = G
Using Earth's mass (5.98 × 10²⁴ kg) and radius (6.38 × 10⁶ m), we can calculate g = 9.8 m/s². This tells us why objects accelerate at this rate when falling.
Cool Connection: The value of g changes slightly depending on where you are on Earth! At the equator, you weigh slightly less than at the poles because Earth's rotation counteracts some gravity and because you're further from Earth's center.
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I think it’s very much worth it and you’ll end up using it a lot once you get the hang of it and even after looking at others notes you can still ask your Artificial intelligence buddy the question and ask to simplify it if you still don’t get it!!! In the end I think it’s worth it 😊👍 ⚠️Also DID I MENTION ITS FREEE YOU DON’T HAVE TO PAY FOR ANYTHING AND STILL GET YOUR GRADES IN PERFECTLY❗️❗️⚠️
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Brad T
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Not only did it help me find the answer but it also showed me alternative ways to solve it. I was horrible in math and science but now I have an a in both subjects. Thanks for the help🤍🤍
David K
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The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
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I found this app a couple years ago and it has only gotten better since then. I really love it because it can help with written questions and photo questions. Also, it can find study guides that other people have made as well as flashcard sets and practice tests. The free version is also amazing for students who might not be able to afford it. Would 100% recommend
Aubrey
iOS user
Best app if you're in Highschool or Junior high. I have been using this app for 2 school years and it's the best, it's good if you don't have anyone to help you with school work.😋🩷🎀
Marco B
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homepage/newPositiveReviewText6
Elisha
iOS user
This app is phenomenal down to the correct info and the various topics you can study! I greatly recommend it for people who struggle with procrastination and those who need homework help. It has been perfectly accurate for world 1 history as far as I’ve seen! Geometry too!
Paul T
iOS user
The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan S
iOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha Klich
Android user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
Anna
iOS user
I think it’s very much worth it and you’ll end up using it a lot once you get the hang of it and even after looking at others notes you can still ask your Artificial intelligence buddy the question and ask to simplify it if you still don’t get it!!! In the end I think it’s worth it 😊👍 ⚠️Also DID I MENTION ITS FREEE YOU DON’T HAVE TO PAY FOR ANYTHING AND STILL GET YOUR GRADES IN PERFECTLY❗️❗️⚠️
Thomas R
iOS user
Knowunity is the BEST app I’ve used in a minute. This is not an ai review or anything this is genuinely coming from a 7th grade student (I know 2011 im young) but dude this app is a 10/10 i have maintained a 3.8 gpa and have plenty of time for gaming. I love it and my mom is just happy I got good grades
Brad T
Android user
Not only did it help me find the answer but it also showed me alternative ways to solve it. I was horrible in math and science but now I have an a in both subjects. Thanks for the help🤍🤍
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
I found this app a couple years ago and it has only gotten better since then. I really love it because it can help with written questions and photo questions. Also, it can find study guides that other people have made as well as flashcard sets and practice tests. The free version is also amazing for students who might not be able to afford it. Would 100% recommend
Aubrey
iOS user
Best app if you're in Highschool or Junior high. I have been using this app for 2 school years and it's the best, it's good if you don't have anyone to help you with school work.😋🩷🎀
Marco B
iOS user
homepage/newPositiveReviewText6
Elisha
iOS user
This app is phenomenal down to the correct info and the various topics you can study! I greatly recommend it for people who struggle with procrastination and those who need homework help. It has been perfectly accurate for world 1 history as far as I’ve seen! Geometry too!
Paul T
iOS user
Understanding Newton’s Law of Universal Gravitation
Newton's Law of Universal Gravitation explains how all objects with mass attract each other. This fundamental law helps us understand planetary motion, orbits, and why objects fall to Earth. You'll see how this elegant formula connects everything from apples falling... Show more
Newton's Law of Universal Gravitation
Ever wonder why planets don't just fly off into space? The answer lies in gravity! When observing Earth's orbit around the Sun, we can see that Earth's velocity is constantly changing direction due to the gravitational force pulling it toward the Sun.
This same force of gravity acts on both objects - Earth pulls on the Sun just as the Sun pulls on Earth. Without gravity, Earth would travel in a straight line through space instead of its circular orbit.
Newton developed his understanding of gravity through his three laws of motion. His first law tells us objects in motion stay in motion unless acted upon by a force. The second law shows that acceleration requires force. The third law reveals that forces come in equal but opposite pairs.
Quick Insight: When an apple falls from a tree, it's not just Earth pulling on the apple - the apple is also pulling on Earth! The difference in their movements is due to their vastly different masses.
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How Gravity Changes
If the Moon weren't affected by Earth's gravity, it would travel in a straight line through space rather than orbiting us. The gravitational relationship between objects depends on both mass and distance.
Newton's big discovery wasn't gravity itself but its universal nature. Everything with mass attracts everything else with mass - from planets and stars to you and your textbooks.
When the mass of an object doubles, the gravitational force doubles too. If both objects double in mass, the force increases by a factor of 4. But distance works differently - if the distance between objects is cut in half, the gravitational force becomes 4 times stronger!
Remember This: Gravity follows an inverse square relationship with distance. This means that doubling the distance makes the force 1/4 as strong, while tripling the distance makes it 1/9 as strong.
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The Universal Gravitation Formula
Newton's Law of Universal Gravitation can be written as: F = G
This formula has several parts:
- G is the gravitational constant
- M₁ and M₂ are the masses of the two objects
- r is the distance between the centers of the objects
When you change values in this formula, the gravitational force changes predictably. If you triple the mass of one object, the force triples. But if you triple the distance between objects, the force becomes 1/9 of its original value.
Try This: Notice how the formula shows that gravity never completely disappears - it just gets weaker with distance. Even objects across the universe exert tiny gravitational pulls on each other!
Sign up to see the contentIt's free!
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Improve your grades
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Gravity and Weight on Earth
Your weight is actually the force of gravity acting on you! On Earth, we can calculate weight using the simple formula Fg = mg, where g equals 9.8 m/s².
This simplified equation comes from Newton's Universal Gravitation formula. When we apply it to Earth:
- Fg = G
- mg = G
- g = G
Using Earth's mass (5.98 × 10²⁴ kg) and radius (6.38 × 10⁶ m), we can calculate g = 9.8 m/s². This tells us why objects accelerate at this rate when falling.
Cool Connection: The value of g changes slightly depending on where you are on Earth! At the equator, you weigh slightly less than at the poles because Earth's rotation counteracts some gravity and because you're further from Earth's center.
We thought you’d never ask...
What is the Knowunity AI companion?
Our AI companion is specifically built for the needs of students. Based on the millions of content pieces we have on the platform we can provide truly meaningful and relevant answers to students. But its not only about answers, the companion is even more about guiding students through their daily learning challenges, with personalised study plans, quizzes or content pieces in the chat and 100% personalisation based on the students skills and developments.
Where can I download the Knowunity app?
You can download the app in the Google Play Store and in the Apple App Store.
Is Knowunity really free of charge?
That's right! Enjoy free access to study content, connect with fellow students, and get instant help – all at your fingertips.
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The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan S
iOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha Klich
Android user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
Anna
iOS user
I think it’s very much worth it and you’ll end up using it a lot once you get the hang of it and even after looking at others notes you can still ask your Artificial intelligence buddy the question and ask to simplify it if you still don’t get it!!! In the end I think it’s worth it 😊👍 ⚠️Also DID I MENTION ITS FREEE YOU DON’T HAVE TO PAY FOR ANYTHING AND STILL GET YOUR GRADES IN PERFECTLY❗️❗️⚠️
Thomas R
iOS user
Knowunity is the BEST app I’ve used in a minute. This is not an ai review or anything this is genuinely coming from a 7th grade student (I know 2011 im young) but dude this app is a 10/10 i have maintained a 3.8 gpa and have plenty of time for gaming. I love it and my mom is just happy I got good grades
Brad T
Android user
Not only did it help me find the answer but it also showed me alternative ways to solve it. I was horrible in math and science but now I have an a in both subjects. Thanks for the help🤍🤍
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
I found this app a couple years ago and it has only gotten better since then. I really love it because it can help with written questions and photo questions. Also, it can find study guides that other people have made as well as flashcard sets and practice tests. The free version is also amazing for students who might not be able to afford it. Would 100% recommend
Aubrey
iOS user
Best app if you're in Highschool or Junior high. I have been using this app for 2 school years and it's the best, it's good if you don't have anyone to help you with school work.😋🩷🎀
Marco B
iOS user
homepage/newPositiveReviewText6
Elisha
iOS user
This app is phenomenal down to the correct info and the various topics you can study! I greatly recommend it for people who struggle with procrastination and those who need homework help. It has been perfectly accurate for world 1 history as far as I’ve seen! Geometry too!
Paul T
iOS user
The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan S
iOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha Klich
Android user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
Anna
iOS user
I think it’s very much worth it and you’ll end up using it a lot once you get the hang of it and even after looking at others notes you can still ask your Artificial intelligence buddy the question and ask to simplify it if you still don’t get it!!! In the end I think it’s worth it 😊👍 ⚠️Also DID I MENTION ITS FREEE YOU DON’T HAVE TO PAY FOR ANYTHING AND STILL GET YOUR GRADES IN PERFECTLY❗️❗️⚠️
Thomas R
iOS user
Knowunity is the BEST app I’ve used in a minute. This is not an ai review or anything this is genuinely coming from a 7th grade student (I know 2011 im young) but dude this app is a 10/10 i have maintained a 3.8 gpa and have plenty of time for gaming. I love it and my mom is just happy I got good grades
Brad T
Android user
Not only did it help me find the answer but it also showed me alternative ways to solve it. I was horrible in math and science but now I have an a in both subjects. Thanks for the help🤍🤍
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
I found this app a couple years ago and it has only gotten better since then. I really love it because it can help with written questions and photo questions. Also, it can find study guides that other people have made as well as flashcard sets and practice tests. The free version is also amazing for students who might not be able to afford it. Would 100% recommend
Aubrey
iOS user
Best app if you're in Highschool or Junior high. I have been using this app for 2 school years and it's the best, it's good if you don't have anyone to help you with school work.😋🩷🎀
Marco B
iOS user
homepage/newPositiveReviewText6
Elisha
iOS user
This app is phenomenal down to the correct info and the various topics you can study! I greatly recommend it for people who struggle with procrastination and those who need homework help. It has been perfectly accurate for world 1 history as far as I’ve seen! Geometry too!
Paul T
iOS user