Gravity is effectively zero at the center of the Earth.
The reason gravity diminishes as you approach the Earth's center is due to the Shell Theorem. This theorem simplifies the gravitational force exerted by a spherically symmetric mass distribution.
Explanation:
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Shell Theorem: The Shell Theorem states that:
- The gravitational force inside a uniform spherical shell is zero.
- The gravitational force outside a uniform spherical shell is the same as if all the mass of the shell were concentrated at its center.
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Applying to Earth: As you move towards the Earth's center, the mass above you (i.e., farther from the center than you are) exerts no net gravitational force on you because you're effectively inside a spherical shell of that mass. Only the mass below you (i.e., closer to the center than you are) contributes to the gravitational force.
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Decreasing Mass: As you get closer and closer to the center, the amount of mass below you decreases. Therefore, the net gravitational force decreases proportionally.
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At the Center: At the very center of the Earth, you are surrounded by equal amounts of mass in all directions. Consequently, the gravitational forces from all directions cancel each other out, resulting in a net gravitational force of zero.
Therefore, while the Earth still has a substantial mass, the geometric distribution of that mass around you at the center creates a zero-gravity environment.
