We can calculate it in terms of meters/seconds or arc-second/second.
What is the conversion between those two terms ?
"The rotational speed of earth is the time required by the earth to rotate
around its own axis. The rotational period of earth changes slightly
depending on the position of observer on earth. If the observer is on
the equator the rotational speed will be approximately 1673km/hr". http://physics.tutorvista.com/motion/rotational-speed.html
Thus, If the Earth's radius = 6.4 x 106m, then, its Angular velocity = 7.3 x 10-5rad/s
"The speed of any point on the earth's surface at the equator due to earth's rotation is, V = r
How many miles per hour is the earth rotating then ?
It depends on your location. For example, " If we move halfway up the globe to 45 degrees in latitude (either north or south), you calculate the speed by using the cosine (a trigonometric function) of the latitude. A good scientific calculator should have a cosine function available .... The cosine of 45 is 0.707, so the spin speed at 45 degrees is roughly 0.707 x 1037 = 733 mph (1,180 km/h). That speed decreases more as you go farther north or south. By the time you get to the North or South Poles, your spin is very slow indeed — it takes an entire day to spin in place".https://www.space.com/33527-how-fast-is-earth-moving.html
Another calculation give us the following numbers:
If the earth travels at 470 meters/second * 60 seconds * 60 minutes, then its speed is, 1,692,000 meters /hr.
There is about 1609.344 meters in one mile. To calculate the speed:
That is, approximately 1,692,000 /1609.344 = 1051. 360 Miles/Hour. (some website vary in this calculation- The above website give a number of 1037 miles/hr).
Either way, this makes sense since the earth's circumference is approximately 24,901 miles.
If we divide that by 1,051.360 miles/Hr, we get time = 23.6785 hours to go one full circle (approximately).Or, more exact, 24,901 / 1037 = 24 .0125 hours.
What if you were an observatory in Hawaii ?
Now, what if you were in Hawaii looking through a telescope at one of the observatories and you tried to keep up with with earth's speed in order to keep either a fixed star or a galaxy in your telescope view ?
Observatories in Hawaii measure the relative rotational speed in terms of arc-seconds/ second. (In Hawaii at Mauna Kea, the Degrees Minutes Seconds: The Latitude is: 19-49'25'' N and Longitude: 155-28'15'' W). http://www.lat-long.com/Latitude-Longitude-366215-Hawaii-Mauna_Kea.html
The earth's relative rotation, at the Mauna Kea Obsevatory is about 15 arc second/seconds. That is the equivalent of a rotational speed of approximately 470 meters/sec. It is not that much more difference than at 19 degrees latitude in Hawaii as we can see from the above calculations.
15 arc seconds is approximately 0.00417 degrees of rotation. Thus, the earth's rotational calculations in Mauna Kea is approximately .00417 degrees/ second.
1 Degree= 3600" (seconds). Therefore, 1/3600" = 0 .0002777777 degrees.
1 arc-second is = .00027777 degrees, or 2.778x 10(elevated to the -4) degrees.
http://www.wolframalpha.com/input/?source=frontpage-immediate-access&i=what+is+an+arc-second
Please see the following web site for conversion from degrees to arc-seconds and vice versa.
A 180 degree turn would be equivalent to 648,000 arc-seconds.
