Hear me out, gravity pulls us towards itself. It is determined by the magnitude of mass of that object. As we go deeper in earth, the amount of mass ‘under’ us decreases and so doesn’t the gravity also decrease? Have been thinking about it since I was 12, I am 15 now 🙂
Edit : It wouldn’t be right to thank just one of you by replying as I have seen some other people do but thanks for all the replies, I really appreciate it.
In: 219
So. I haven’t seen this explained yet in an approachable way. The formula for gravitational force is divided by distance squared. If you were to start by standing on the surface of the planet, and measure the distance between yourself and every particle on the planet, invert those measurements, and add them together; you get the acceleration due to gravity pulling you down. Everything is below you, so the directions all add up. Start going down below the surface, and now some of those particles are above you. They subtract from the direction of force gravity – the mass above you is pulling up.
However, you are getting closer to the center of the spherical planet. The average distance between you and the particles below you is still decreasing more than the gravity pulling you back up.
In essence, the slice of the planet above you is pulling you up. For a while, that slice above you is small compared to how close you are getting to the rest of the mass below you. As others have shown in the graph, there is a point where the slice of the planet above you is pulling you back more than you gain by going deeper. Then gravity goes down gradually until you get to the center of mass. At that point, there is no acceleration due to gravity.
PS: The tools you need to solve this for yourself come with calculus.
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