The gravitational acceleration exerted by the mass of a wet, spinning tennis ball is too small compared to the centrifugal acceleration generated by its rotating motion. As a result, the water escapes away from the tennis ball, unlike Earth.
A wet spinning ball is a sphere, spinning & wet, like Earth. But the water goes away from the ball, unlike Earth. Flat Earthers use it to “disprove” spherical Earth. In reality, the magnitude of the involved accelerations in the two cases are different.
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“Down” is the same direction as Earth’s gravitational acceleration, toward Earth’s center. “Up” is the opposite, or away from Earth’s center. This applies to all observers on Earth.
Flat-Earthers like to question & ridicule about what would occur on the people “down” there. They just do not understand that to the people on the other side of Earth, “down” is still toward Earth’s center, like it appears to everyone else.
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At a lower altitude, the air is denser, and objects weigh more. On the other hand, at a higher altitude, the air is less dense, and objects weigh less.
Flat-Earthers deny gravity and invented the “explanation” that an object falls only because it is denser than the air surrounding it. But if it were true, objects should weigh more at a higher altitude where the air is less dense. But they weigh less instead, disproving flat-Earthers’ density theory.
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A density tower is formed by layering immiscible liquids of different densities on top of each other. It is possible because Earth’s gravitational acceleration pulls denser fluid particles stronger and displace less dense ones upward.
Flat-Earthers claim that the possibility to have density towers disproves gravity. In reality, a density tower cannot form without the presence of acceleration, like Earth’s gravitational acceleration.
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When aboard an airplane flying at cruising speed, we will not be able to feel that the plane is, in fact, moving at speed of more than 900 km/h. But if the plane changes its speed, turns or changes its altitude, we can easily feel it.
The same thing happens with the motion of the Earth. Due to Earth’s rotation, the surface of the Earth is moving at 1656 km/h near the equator. We never feel it because the speed is constant, or in other words, the acceleration is zero.
Continue reading “Human Perception of Speed and Acceleration”