At the poles, how fast does the earth spin?
Assuming that the equatorial radius is 6378 km = 3963 miles, the spin speed near the equator (latitude 0 deg) is 1037.5 mil/'h =1669.7 km/h, nearly.
For example, at latitude 60 deg N or Sm the speed is halved.
This way, we can say, Poles (lat = 90 deg and cos 90 = 0) are not rotating
Of course, the angular speed 15 deg/h remains the same , everywhere.\