Earth rotation

[Yai]

How fast does the earth rotate ? ie. MPH

[rekstout]

Taking the diameter at the Equator as 7926 miles (Google value), the circumference of the earth will be 24911 miles and since we know it rotates 360 degrees in 24 hours, the speed will be roughly 1038mph.

[lisaj]

or simply 1/1440 RPM

[Ewood27]

I'm sure Rekstout's arithmetic is correct at the Equator. At 60 degrees North the speed would be half that. In the UK we are about 55 degrees North, so the speed will be just over half the Equator value - something like 600 m.p.h.

[sddsddean]

And don't forget orbital velocity which is about 66,600mph. So when you are sitting reading this, you are travelling at over 67,000mph! You don't suppose the Hubble telescope is really a big speed camera and we are all about to get the fine? (BTW, you could also add in galactic rotation velocity and drift, but I think thats getting a bit beyond the bounds of the original question!)

[Squirrel]

Using the cosine rule I wrote down a rough formula for the "speed" of the ground at a certain latitude.

It's clumsy and it won't come out too well on screen, but anway:

' θ = angle of latitude (N or S, in positive �)

' r ≈ radius of the Earth (3960 miles)

speed = (π/24)�√[2r�-{2r�cos(180-2θ)}]

Some of the symbols might not appear; also, sorry if you see a load of jumbled words and html tags (never tried them before).

My speed came out as 624 m.p.h.

[landie]

Are you trying to tell me that the universe doesn't revolve around posh spice.