> Over millions of years, Earth's rotation has been slowed significantly by tidal acceleration through gravitational interactions with the Moon. Thus angular momentum is slowly transferred to the Moon at a rate proportional to r − 6 r^{{-6}}, where r r is the orbital radius of the Moon. This process has gradually increased the length of the day to its current value, and resulted in the Moon being tidally locked with Earth.
beatle42 t1_j96espg wrote
Reply to so why don't earth slow down do to the drag of the water created in the tidel forces by the moon? by SnurrDass
It is. A quick read in Wikipedia notes:
> Over millions of years, Earth's rotation has been slowed significantly by tidal acceleration through gravitational interactions with the Moon. Thus angular momentum is slowly transferred to the Moon at a rate proportional to r − 6 r^{{-6}}, where r r is the orbital radius of the Moon. This process has gradually increased the length of the day to its current value, and resulted in the Moon being tidally locked with Earth.