How to think about gravity
--Jon Bergman
What is gravity?
I think most people will say, "Something that moves upwards is bound to fall, and that's gravity!" That's not wrong, but you know what? True gravity is not entirely like that!
Academically, gravity is a formula: . Where G is the gravitational constant, M1 and M2 are the masses of two objects attracting to each other, respectively, and R is the distance between them. This formula is not as simple as it seems!
What exactly does this formula mean?
This formula means that any object will attract each other, that is, if you have two objects — two things at random — they will attract each other. Let's think about it, suppose you throw a rock down on the edge of a cliff, what happens?
We all know that stones fall to the ground. But that's all? Is there anything else going on? Obviously, the law of universal gravitation says that two objects are attracted to each other, that is, the stone and the earth are attracted to each other. So when the stone falls on the earth, the earth will also "fall" to the stone.
You must ask me: "Will the earth "fall" upward towards the stone?" ”
yes! That's what I mean. The reason we can't see the Earth "falling" upward toward the stone is because the two objects will move toward each other in proportion to their own mass, and the mass of the Earth is much greater than the mass of the stone, so the Earth has only moved a very, very small distance, and the stone itself is very small in mass, so it moves much farther relative to the Earth.
To give you a better understanding of gravity, let's look at another example: Suppose two young people in spacesuits float in outer space, far away from all planets and stars. At this point we will find that they are attracted to each other. Because they have quality, they move toward each other. They will be attracted to each other, and that's gravity!
Perhaps, with one more example, I will make it easier for you to understand gravity. Have you ever tried playing with two magnets at the same time? It is a magnet with the south pole and the north pole. When you bring two magnets closer to each other, they attract each other and dock, and the attraction gradually increases as they get closer. Try to think of the mass of the object as the strength of the magnet, and the distance between the objects is like the distance between two magnets. But I need to emphasize that this is not to say that gravity and magnetism are the same thing, it's just that they behave similarly.
Let's think back to astronauts. Astronauts weigh less on the moon than they do on Earth. Why? We know that the mass of the Moon is 1/6 of the mass of the Earth, so the Moon's gravitational attraction to astronauts is smaller, just as the Moon is a weaker magnet, and the attraction between them is not as great as the attraction between astronauts and The Earth.
In addition, the distance between objects is also important. When we play with magnets, the attraction between the magnets gradually increases as they approach each other, and the same applies to gravity. For example, the Sun is the most massive object near the Earth, and because of its very large mass, it manipulates most of the gravitational force in the entire solar system, but because of its distance from the Earth, even if the Sun is a huge magnet, the attraction between it and the Earth is not so strong.
Let's review the formula for the law of gravitation again: . We can see that gravitational force corresponds to a numerical value: the gravitational constant G is multiplied by the mass of the first object M1, and then multiplied by the mass of the second object M2 - assuming that M1 represents the mass of the Sun and M2 represents the mass of the Earth - and then divides by the square of the distance between them, so that the gravitational force between the Sun and the Earth is obtained.
Now, you can also enter your mass to the mass of the Earth, and the square of your distance from the center of the Earth, so that you can draw out the gravitational pull of the Earth and the force of the Earth attracted to you.
What exactly is gravity?
Now, we can say with certainty that gravity means that any object will be attracted to each other. In addition, you may wonder how gravity is formed? Why do two objects with mass attract each other? The answer is - we don't know! For scientists, the cause of gravitational attraction remains a mystery to this day, and we have never reached a conclusive conclusion.
The cause of gravity is one of the biggest unsolved mysteries in science!
Resources
1. Wikipedia Encyclopedia
2. Astronomical terms
3. Minji Seo- Yolanda Zhang-Yingzi-TED-Ed
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