Who figured out the Earth is round? - NASA
Pythagoras reasoned that if the Moon was round, then the Earth must be round as well. After that, sometime between 500 B.C. and 430 B.C., a fellow called Anaxagoras determined the true cause of solar and lunar eclipses - and then the shape of the Earth's shadow on the Moon during a lunar eclipse was also used as evidence that the Earth was round.
A non-spherical Earth's gravitational potential? - Physics Forums
2020年12月19日 · What is a non-spherical Earth's gravitational potential? A non-spherical Earth's gravitational potential refers to the variation in the strength of Earth's gravity due to its irregular shape. The Earth is not a perfect sphere, and this causes differences in the distribution of mass and thus, the strength of gravity in different locations.
Did ancient civilizations believe in a spherical Earth like Pythagoras …
2008年8月21日 · In summary, classical Mediterranean thinkers alluded to a spherical Earth, though with some ambiguity. This idea influenced Pythagoras, who reasoned that Earth and the other planets must be spheres, since the most harmonious geometric solid form is a sphere.
Why doesn’t the water fall out of the Earth? - Physics Forums
2017年12月2日 · The Earth's tilt, axis of rotation, and orbital plane are all mentioned as factors, but ultimately, it is gravity that holds the water in a spherical shape and prevents it from spilling out. The conversation also touches on the effects of gravity in other situations, such as the space station and the concept of "down" being towards the center ...
Displacement Question: Flat Earth vs. Spherical Earth - Physics …
2009年9月13日 · If we assume that the Earth is spherical, we can use the Pythagorean theorem to calculate the displacement. However, the result will be different depending on the size of the Earth. For example, if we assume the Earth has a radius of 6,371km (the average radius of the Earth), the person's displacement would be approximately 5.5km SE.
Seismic ray-tracing, when does a spherical Earth matter in practice?
2021年4月11日 · The Earth's spherical shape has an effect on the propagation of seismic waves below 35km (the depth of the Moho), so it’s important to take that into account when interpreting seismic data. In terms of what kinds of events would generate seismic waves below the Moho, there are a variety of different sources.
What is the Capacitance of the Earth-Ionosphere System? - Physics …
2012年11月29日 · In summary, the Earth and ionosphere can be considered as a spherical capacitor with a potential difference of 350000V. The capacitance of the system can be calculated using the formula C=4πε0/(1/Rb-1/Ra), where Ra is the radius of the Earth and Rb-Ra is the difference between the radii of the Earth and ionosphere.
Centripetal force on a person on the Earth - Physics Forums
2021年6月5日 · The underlying approximation in these is that the Earth is an inertial frame. Some textbooks mention the approximation explicitly but most don't bother. In this approximation, a plumb bob points in the direction of ##\vec g## which …
Exploring the Effects of a Spherical Earth - Physics Forums
2010年10月26日 · There is a plethora of evidence that supports the idea of a spherical Earth, such as photographs of the Earth from space, measurements of the Earth's curvature, and the observations of lunar eclipses. Additionally, ancient civilizations like the Greeks and Chinese also believed in a spherical Earth based on their own observations and reasoning.
Calculating Distance on a Spherical Earth Using Trigonometry
2009年3月11日 · FAQ: Calculating Distance on a Spherical Earth Using Trigonometry What is the definition of distance of a great circle? The distance of a great circle is the shortest distance between two points on a sphere. It is measured along the surface of the sphere, rather than through its interior. How is the distance of a great circle calculated?