Earth - Mean Orbital Velocity

The Mean Velocity of the Earth in it's orbit around the Sun is approximately 29.78 km/s

The Math / Science

The Earth travels in nearly circular path around the Sun.  The mean radius of that circle is called an Astronomical Unit (ua).  Using the simple formula for the circumference of a circle:

    `C = 2 * pi * r`

we can compute the distance travelled in a year.  Doing the math, where velocity is distance decided by time, we can compute the velocity:

    `v = (2*PI*r)/(1 year)`

Now, we just have to convert astronomical units per year into kilometers per second to get 29.784735696231 km/s.