Tides due to the moon vs. the sun?

[billiards]

The easiest way to deal with this is to get rid of the rotational motion altogether. Without the moon being in orbit and the Earth rotating, the tides would still be there (for a little while, anyway - until the moon crashed into the earth!).

Exactly! The only thing necessary condition for tides (or differential acceleration) is that the object be in free fall. The effect of rotation enables us to "see" the tides by standing in one place, and the effect of orbital free fall keeps the whole experience going on and on.

 

[D H]

Exactly! The only thing necessary condition for tides (or differential acceleration) is that the object be in free fall.

The only necessary condition for tides to exist is that the object be where it is. It does not have to be in free fall. Outfit the Moon with some BIG honking rocket engines that are capable of making the Moon hover 384,399 km away from the center of the Earth without orbiting and the tides will still exist.

 

[MooChubChub]

Alright, so this topic is old. But there is one thing I've been puzzling over for the past half day.

Say we ignore the sun's effect on the tides and just went with the moon-earth system. I understand why the tides happen, but I don't understand why, in an idealized model of the Earth (sphere covered completely with water , no variation in water depth), the tides on either side of the Earth are equal.