SIMPLIFIED: "13.2: Newton's Law of Universal Gravitation"

Link: https://phys.libretexts.org/Bookshelves/University_Physics/University_Physics_(OpenStax)/Book%3A_University_Physics_I_-_Mechanics_Sound_Oscillations_and_Waves_(OpenStax)/13%3A_Gravitation/13.02%3A_Newton's_Law_of_Universal_Gravitation 

Note: The above image is from the original article.

The linked article above talks about Newton’s Law of Universal Gravitation. The basic idea is this: there is a force that exists between any two objects with mass. To calculate this force, this equation can be used: 

This force is a gravitational force, meaning anything with mass has a force being exerted on it by another object with mass. Looking at the equation, we can see that if you increase the mass of any object, the gravitational force between the two objects increases. However, if you increase the distance between the two objects, the gravitational force between the two objects decreases because the distance is a variable in the denominator. You also might be wondering what G represents. G is the gravitational constant, and its value is 6.67 times 10^-11 (N*m²)/kg². So yes, the value of the gravitational constant is very small if you notice that the exponent on the 10 is a -11, not a positive 11. 

In physics class, this equation is very commonly used when studying forces in between planets. Planets have huge masses and therefore there is a gravitational force between the planets. If you were to go to space and near Earth, there would be a gravitational force pulling you closer to Earth. Earth would be mass 1 in this case, and you would be mass 2. On the other hand, there is a gravitational force from you that is pulling the Earth closer to you. That seems pretty hard to grasp, but because Earth’s mass is so huge, the force from you on the Earth doesn’t cause much acceleration on the Earth. But it exists. You might notice that the setup of this equation is very similar to Coulomb’s Law. We have simplified the entire concept of Coulomb’s Law so search for that article if you are curious about it. Unlike Coulomb’s Law, with Newton’s Law of Gravitation, the gravitational force is an attracting force. The mass of anything is always going to be positive, so gravity can only attract objects. That is an important distinction between Newton’s Law of Gravitation and Coulomb’s Law.