# Tag Info

## Hot answers tagged gravity

31

It is the pressure gradient that is proportional to the local gravitational force. When that force is integrated over a distance, the pressure gradient is integrated to accumulate a total pressure. The maximum occurs at the point towards which gravity is directed in a spherical mass, which is the center. True, gravity at that point is zero, but it and ...

12

The previous answers do a fine job already. But I'll try to add a simple thought experiment. Imagine three objects floating in space, clumping together by gravity: ### ### #A#|c|#B# ### ### Mass A, the negligible mass c and mass B, equal to A. The center is attracted to A and B and their gravity cancels out. However, A presses against c, because it is ...

9

Pressure at the center of the earth is non-zero. You're correct that there's no gravitational force at the center of the earth, but that doesn't mean pressure is zero - the pressure comes from the many miles of rock sitting above the center of the earth. As an analogy, think of a balloon. The pressure inside is higher than ambient because the elastic skin of ...

5

The moon does orbit the sun but it also orbits the earth. But your assertion that the earth's gravity is weaker than the sun's is not universally true. If the sun's gravitational pull were greater than the earth's HERE on the earth, the sun would literally suck everything not attached to the earth's surface into itself. Clearly that's not happening. ...

3

Citing from Wikipedia: $Y_l^m$ is called a spherical harmonic function of degree $l$ and order $m$. If we take the real part of the spherical harmonics only, there is a nice visual explanation for order and degree. The order $m$ is the zonal wave number, that is how many waves we count walking around the sphere at constant latitude. The degree is a little ...

3

Imagine the whole ball being separated into a handful of concentric shells, with the outermost shell being the crust with the surface, and the lower shells ever deeper, hotter, and ghastly regions of the internals of our planet. Now, just for the thought experiment, forget that each individual shell has "stuff" going on in itself, and just imagine ...

2

Edit: This answer refers to the first version of this question which asked about "gravitational waves". Typically, the term "gravitational wave" is reserved for distortions ("strain") in spacetime, in accordance with General Relativity. Gravitational waves are a property of spacetime and can thus propagate in empty space. In ...

2

A complicating factor will be the change in density with temperature. So for this I will assume a constant density of water. As the thickness of the water layer is quite small compared to the size of Earth (given as 2.6 km by the answer to the other question) I think an approximation with a constant g at any particular location should give a fairly ...

1

The sun's gravity is strong but the the earth overwhelms the sun's gravity ,and the moon is in the in the place where the earth's gravity overwhelms the sun's, so in short the moon orbit the earth because it is in the place where earth's gravity overwhelms the sun's

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