Question

What is the Iinear speed of a point on Earth's equator? What if the point was at latitude -15.0° ?

Answer 1

At the equator, linear speed with respect to the polar (day/night spin ) axis is 463.82 meter/s = 1521.8 feet/s, At latitude `15^o N and 15^o S`, this speed is 447.77 meter/s = 1469.1 feet/s.

Explanation:

In the day-night spin, any point on the Earth moves around Earth's

axis in its latitude circle.

Speed = (distance traveled in a second)/second..

The circumference of the equator = `2 pi X 6378` km.

The number of seconds in a day = 24 X 3600

So, at the equator, speed = `( 2 pi X 6378 ) / ( 24 X 3600 )` km/s =

0.46382 km/s = 463.82 meter/s = 1521.8 feet/s.

At `+-15^o` latitude Earth's ( a little less than equatorial )

radius is

6374.5 km, nearly.

The latitude-circle circumference

= `2 pi X 6374.5 X cos 15^o` km.

So, the speed is (`2 pi X 6374.5 X cos 15^o`)/(24 X 3600)=

0.44777 km/s = 447.77 meter/s = 1469.1 feet/s
.
Thanks to Johannes C for pointing to the error in the unit km,

used for meter, in my earlier edition...