What is the tide?
In: Physics
The force of gravity varies with distance. So, e.g. the part of the Earth closest to the Moon is pulled harder than the center of the Earth, which is pulled harder than the part farthest from the Moon. So the Earth experiences a slight stretching along the line from Earth to Moon.
But the Earth is rotating much faster than the Moon is going around the Earth, which means that about 6 hours later, the parts that were at extreme distances are now at middling distances, and the stretching is relaxed. And then 6 hours later still, they’re at extreme distances again. So there’s this continual sloshing, as ocean water rises and falls, even more than the rock underneath rises and falls.
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