Our moon has been slowly drifting away from Earth over the past 2.5B yrs

Re:Our moon has been slowly drifting away from Earth over th... by ncallaway on Tuesday October 18, 2022 @02:20AM (#33243612)

I haven't done the math, but I strongly suspect that the potential energy (from moving away from the source of gravity) is increased more than the kinetic energy (from the reduced velocity) decreases.

So, I would think when the moon moves away from the earth, its total energy increases. Thus, the earth's energy decreases (in the form of slightly reduced rotational kinetic energy)

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Re:Our moon has been slowly drifting away from Earth over th... by onos on Tuesday October 18, 2022 @07:17AM (#33245617)

That’s right. The radius is set by the force

mv^2/r = GMm/r^2.

—> mv^2/2 = 0.5 GMm/r

—> Kinetic plus potential = - 0.5 GMm/r

This goes up with r.

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Re:Our moon has been slowly drifting away from Earth over th... by sliken on Tuesday October 18, 2022 @04:23PM (#33253348)

Earths rotational velocity is decreased (longer days) and added to the moon which increases it's potential energy (distance relative to earth), increases it's orbital height, and increases the period of it's orbit (the lunar month).

But once the lunar month = earth day the transfer will stop and the moon will slowly approach earth again, until it hits the roche limit and becomes a ring.

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