Question

gravitational force becomes zero at center but we say that earth attracts everything at center?why?

Answer 1

From the Newtonian view, we know that gravity is a force exerted by everything that has mass. This means that the gravitational field from the Earth is not only from the center, it is the sum of all the particles, molecules, or atoms that makes up the Earth.

Why is the there no g-force in the center of the Earth? Because at the center, the mass above you the the same as the mass beneath you; the mass in front of your the the same as the mass behind you, and so on. Therefore, all the gravitational forces cancel out each other. Therefore, the gravitational acceleration at the ideal center of the Earth is 0.