The apple hit Newton on the head and inspired him to write 400 words.

Everyone must have heard of Newton and the apple tree, but do you know what this is about?

One day, Newton took a nap under the apple tree. Suddenly, a naughty apple hit Newton with a plop. Newton woke up from his dream ... what would you do if it were you? Kick the apple angrily? Pick it up and eat it Go back to sleep? However, Newton would not do that. He's really weird. He thought, why doesn't the apple run? Still hitting me? Will the moon also fall? Did you pull them? Maybe he was born a scientist. It is these problems that pave the way for gravity theory. ...

Of course, this is just a children's version of the fairy tale. If Newton is so talented and everyone is a scientist, he can see the existence of gravity, which is impossible, and I will only pick up the apple and eat it. I don't think I will teach you physics today, and I won't have the courage to be a scientist. Because miracles always happen to geniuses. Perhaps the apple landing event is an important stimulus, but it is impossible for a single stimulus to make such a big discovery! Then let me tell you the following story. ...

Let me talk about it first. Newton understood the concept of inertia put forward earlier by Galileo. He knows that stars move in a straight line at a constant speed without external force. He also knows that if the speed or direction of a moving object changes, it will certainly play a powerful role. Newton at that time, influenced by the circular orbit of the earth around the sun proposed by astronomer Copernicus, may be deeply confused about the orbit of the moon. The orbit of the moon is not a straight line, but a circular orbit around the earth. But he already knew that it was the sea that put forward the theory that objects need centripetal force to do circular motion. Astronomically speaking, planets orbiting the sun should also need centripetal attraction, but what is this force? He really knows how to ask questions, so he asked the following questions:

1. The orbit can be circular or elliptical. What kind of action can form such a track?

2. The sun is in the focus of the ellipse, which indicates that the planets revolve around the sun. What makes them revolve around the sun?

3. From the relationship between the period and the orbital radius (the square of the period is directly proportional to the cubic of the orbital radius), what kind of way is this?

So the next day, he saw his nephew playing with the ball, so he tied the ball with a rope, turned it for several weeks, and threw it out and found that the ball was moving in a straight line. So suppose ... he came up with a bunch of hypotheses. (Too curious, so the truth was born after a hundred question marks! ) started his experimental career. ...

Let me say a hypothesis: the moon falls.

As I said before, Newton thought of the moon, and Newton further developed his idea. He compared the falling apple with the falling moon. Newton later learned that if the moon didn't fall to the earth, it would move in a straight line and eventually get out of the orbit around the earth, so he thought that the moon was falling around the earth (moonfall was very serious). Therefore, the moon must have fallen below the one it should have gone when there was no external force. Newton boldly assumed that the moon attracted by gravity was just a projectile orbiting the earth. As for how the tangential velocity of the moon came from, it may have been decided when BIGBANG and the universe were created, and the tangential velocity of the moon will determine whether its orbit around the earth is circular, elliptical, parabolic, hyperbolic or hit the earth!

He was a genius and finally came up with the theory of gravity, but he was timid and waited for 20 years to put it forward. Maybe he wants to demonstrate it again, but his accomplishments in mathematics are too high, so we know gravity. He invented calculus and calculated the radii and perimeters of some planets, such as the earth and the moon. He published the theory of universal gravitation. Let me sum it up.

Newton didn't find gravity. He found that gravity is universal. Every object attracts other objects, and the magnitude of this attraction is only related to the mass of the objects and the distance between them. Newton's law of universal gravitation shows that every object attracts every other object, and the gravitation between two objects is directly proportional to its mass, and decreases with the square of the distance between the centers of the two objects. Newton developed calculus in order to prove that only a sphere can concentrate the total mass of the ball on the center of mass of the ball to represent the total effect of gravity of the whole ball. However, no matter how far away from the earth, the gravity of the earth will never become zero. Even if you are taken to the edge of the universe, the gravity of the earth will still act on you. Although the influence of the earth's gravity may be masked by the massive objects near you, it still exists. No matter how small or far away, every object will be affected by gravity and spread all over the space, just as we say that everything is the same.

Look at the full text. Have you figured out what it means? Newton, he is just the kind of spiritualist who can't get what he wants. Don't think about science, teachers and authority. Ask if you find it. If you don't understand, you should study it. Whatever the outcome, it doesn't matter what the outcome is.

Remember to ask what's next, the real bottom is reason!