Effect of Earth's Spin Stopping on Gravity at Sea Level

Understanding Gravity and Earth's Rotation

Technically, gravity would stay the same even if the Earth stopped spinning. The fundamental law of physics, Newton's law of universal gravitation, dictates the force of gravity, which does not depend on the object's rotation. However, if the Earth were to stop rotating, some variables would change, leading to interesting effects.

Centrifugal Force and Its Influence

The Earth's rotation generates a centrifugal force that acts outward from the axis of rotation. At the equator, this force is greater than at the poles. When the Earth stops rotating, the centrifugal force would decrease, and the radius of the planet might increase by a small amount. This change could lead to a slightly different gravitational feeling at the equator.

Impact on Satellites and Landing Missions

Any spacecraft orbiting the Earth would remain unaffected, as satellites' orbits are independent of the Earth's rotation. However, landing on a non-rotating Earth would require significant adjustments. The Earth's surface would be different, and a continuous hard turn at the radius of the planet would be necessary. This would require more force than gravity alone, leading to a slight bulge at the equator.

Consequences for Human Perception and Mass Calculation

At the equator, the reduced centrifugal force would make people feel slightly heavier, even though the gravity itself remains the same. The net force on their body would increase, making them perceive their weight as higher. This effect would be negligible for most people but could be noticeable for people weighing more.

Theoretical Models and Extreme Scenarios

In a purely hypothetical scenario, if the Earth were a perfectly liquid object with special properties allowing it to maintain its shape, spinning it fast enough would transform it into a disk shape, similar to a pizza. While this is not possible in reality, theoretical models like those proposed by Hal Clement for black holes can provide fascinating insights.

Pole and Equator Differences

Due to the Earth's rotation, there is a noticeable difference in effective gravity between the equator and the poles. At the equator, gravity is about 0.3% less than at the poles. This difference is significant enough to matter for precise mass calculations, such as those required for valuable cargo.

Conclusion

In summary, if the Earth were to stop spinning, gravity itself would remain constant, but the reduction in centrifugal force would create a slight increase in perceived weight at the equator. The consequences of such a change would be significant for various aspects of life on Earth, from physics to engineering and landing missions.

Additional Readings and Reference

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