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Round Earth


Why not flat earth?

Have you ever wondered why is the earth round? Why is everything out there (stars and planets) round? Why isn’t the earth flat so we won’t fall down at the bottom of earth if the earth is round?

Of course the answer is gravity. Gravity is one of the 4 fundamental forces, and is (almost) well-described by Isaac Newton’s law of gravitation (Corrected by Albert Einstein’s general theory of relativity). Newton found that everything that has mass, is attracted to to one another by a force that is directly proportional to their masses, and inversely proportional to their separation’s squared. For objects with small masses, the force is minusculed (That’s why me and you are not attracted to each other). But for object as massive as the earth, the force is obvious.

The feeling of gravity is just you and the earth being attracted to one another.

Every portion of an object with mass attracts other portion towards it. So the average of all the pulling, is the attraction between the centre of mass. A massive object that is pulling everything in towards its centre, will always stay in the most stable shape, a sphere so that any point on it will be pulled towards the centre by the same force.

You may create the earth or the stars as any shape you like (ie. a flat disk), but with consideration of the gravity, it will eventually collapse into a sphere!


Keywords

  • 4 Fundamental Forces: There are four fundamental forces at work in the universe: the strong force, the weak force, the electromagnetic force, and the gravitational force. They work over different ranges and have different strengths. Gravity is the weakest but it has an infinite range.

  • Directly Proportional: The relationship between 2 quantities where one quantity increases or decreases constantly with respect with another quantity.

  • Inversely Proportional: The relationship between 2 quantities where one quantity increases with respect to a decrease in another or vice versa.


Images


References

https://home.cern/science/physics/standard-model
https://www.youtube.com/watch?v=Xc4xYacTu-E
https://www.youtube.com/watch?v=VNqNnUJVcVs