“Eli5” Tidal acceleration of the moon. Does the mass of the moon affect this?
Hi,
I’ve just started reading up on black holes and, damn this is so interesting but mind boggling so I’m going all way back to understand the basics of gravity that we have knowledge on well enough.
I’ve read up ( bought some extra books for references ) but does the mass of our natural satellite affect our tidal acceleration or is it purely based on gravity between that, us and the Sun?
Thank you in advance
In: 3
The moon’s (or any object’s) gravity is directly proportional to its mass, so yes.
If the moon was a hollow paper mache sphere you wouldn’t get nearly as much tidal effect here on Earth.
The force between the two is G(m1 x m2)/r^2
The moon does exert tidal drag on the Earth, slowly sapping rotational energy and making days longer.
The much more massive Earth has done the same to the moon, dragging it so hard that it’s now permanently fixed with one side facing Earth.
Adding to the other comments, tidal forces follow an inverse **cube** law, not an inverse square law. The reason is that they’re caused by differences in gravity, not just gravity itself.
As evidence of the cube law, we feel tides from both the moon and the sun, but those due to the moon are about twice as strong. The sun is almost 400 times farther away than the moon but its mass is 27 million times greater, i.e., roughly half of 400^(3).
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