Earth makes one complete spin on its tilted axis every 24 hours. Viewing from the north pole, the earth is actually spinning counterclockwise from west to east with a speed of approximately 1000 mph at the equator. The spin speed decreases as we move closer to the pole as it obeys conservation of angular momentum. The rotation is actually slowing down due to conservation of angular momentum. The earth loses its angular momentum to Moon’s orbital momentum due to tidal friction.
Have you guys ever think about what will happen if the earth’s rotation ever stop?
As it slows down, it might eventually stop spinning if it lost all angular momentum. If it happened one day, imagine that only motion earth has is when it moves on its orbit around the sun, orbital period will remain as it is now, 365 days. But now, day and night only depends on orbital movement. This means, at one place, it can only have one daytime and one night time in a year that lasts for six months each.
If it is a sudden stop, inertia will cause everything on the surface to keep moving at the same speed as it has before, 1000 mph. This tremendous speed will sweep everything away into the air. The ocean will also keep moving but it will not be floating in the air, it will cause tsunamis that will wash away the earth surface up to 17 miles from a seashore.
The spinning gives the earth bulge at the equator to ensure that ocean is kept about 8 kilometers from each pole. Without the spin, the bulge will disappear, changing the initial flattened sphere into a perfect sphere. This causes the ocean to move to the poles, splitting it to two oceans and continents will merge forming one huge continent extending from the equator.
The core also will stop rotating. The movement if mantle around the core produces magnetic field and also magnetosphere that will shield the earth from high energy particles brought by solar wind. The absence of magnetosphere will cause the harmful particles to strip down everything on earth surface leaving a large bare land.
Here’s the video of what might happen if the earth ever stop spinning.