Drag

Drag is a force acting opposite to the relative motion of an object moving with respect to a surrounding fluid. The higher the density of the fluid, the higher the magnitude of the drag.

Flat-Earthers claim that it is impossible for satellites to have such high speed. Usually, they would compare the speed of satellites to something like the SR-71 Blackbird, which holds the record as the fastest aircraft. They are wrong. At the altitude where satellites reside, the air density is several magnitudes smaller compared to near the surface, and thus, the drag experienced by satellites is also several magnitude smaller.

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The Moving Vehicle Analogy

“If the Earth is rotating, why when we throw a rock upward, it would fall to the original location?” The explanation is that the rock maintains the momentum before it is thrown. Before it is thrown, the rock has the same velocity as the surface of the Earth, it does not suddenly lose its momentum after being thrown, and there’s nothing exerting a force to alter its trajectory.

We usually use the moving vehicle analogy to illustrate this. If we throw the rock upward inside a moving vehicle, it would also fall to the original location, despite the fact that the vehicle is moving.

Flat-Earthers reject the analogy. Their usual excuse is that the atmosphere is not separated from space, and the rock is thrown “inside” the vehicle, separated by the body of the vehicle from the outside. They offer the analogy of being on the top of a moving vehicle as the correct analogy. They are wrong.

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The Ball and Water ‘Experiment’

Gravity is the attraction between objects with mass. The attraction is greater if the objects are more massive. The shape of the object practically doesn’t affect the magnitude of the attraction provided the objects are spaced far enough.

Flat-Earthers like to perform the ball-and-water ‘experiment’. They spray water to a ball, then observe the water does not stick to the ball the same way seawater stays on the surface of the Earth. They would conclude that ‘gravity does not exist’. They are wrong. The spherical shape of the Earth (and the ball)does not cause gravity, Continue reading “The Ball and Water ‘Experiment’”

Classical vs Modern Physics

Classical physics —like Newton’s law of motion, and Newton’s law of universal gravitation— has been superseded by Special Relativity, General Relativity, and Quantum Mechanics. But it doesn’t mean classical physics is wrong. Classical physics is still applicable when the parameters approach common, terrestrial values we use every day.

Pseudoscientists —including flat-Earthers— often misunderstood this and take the fact that classical physics is still being taught in schools as ‘proof’ of deception and the failure of modern science to explain the world. They are wrong.

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The Directions of Up and Down

The directions of up and down are determined from the direction of the Earth’s gravitational acceleration. Up is in the opposite direction, and down is in the same direction as the Earth’s gravitational acceleration.

Flat-Earthers are often seen making fun of this fact. They show us ‘upside down’ pictures taken in the southern hemisphere. They are wrong. To anyone in the southern hemisphere, down is in the same direction as the Earth ‘s gravitational acceleration, the same as anyone in the northern hemisphere.

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Velocity is Measured From Specific Frame of Reference

A widespread misunderstanding within the flat-Earth victims is related to velocity/speed. They seem to think velocity is absolute, while in reality it is measured from a specific frame of reference. Example:

“If the Earth is in motion around the Sun at 30 km/s, and Apollo traveled at only 11 km/s, then how could Apollo astronauts possibly make it back to the Earth?”

We used to measure velocity/speed relative to the surface of the Earth. But it is not always like that.

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Free Fall

Things fall down because of gravity. The mass of the Earth causes everything to fall down at 9.8 m/s² near the surface of the Earth. This constant is called ‘gravitational acceleration’ and usually denoted by ‘g’.

Most flat-Earthers deny the existence of gravity. According to them, things fall down because of density or buoyancy, not gravity. They are wrong.

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Hot Air Balloon and the Force of Gravity

A hot air balloon rises because it has buoyancy. Buoyancy is the upward force that is exerted on the trapped hot air because its density is lower than the surrounding air. If buoyancy is greater than the force of gravity — or the weight of the balloon—, then the balloon will rise.

The basic physics escape most flat-Earthers. To them, the fact that a hot-air balloon rises is an ‘evidence’ that gravity does not exist. They believe things go up or down because of density. They are wrong.

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The Ability of Humans to Perceive Speed and Acceleration

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.

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