First we know that Earth moves around the sun once per year.
If Radius = 150,000,000Km, then the circumference of Earth's orbit must be:
C = 2 x R x Pi
C = 2 x 150,000,000 x 3.141529
C = 942,458,700Km per year
Divide that by 365.25 days, and we get:
C = 2,580,311Km per day
Further divide that by 24 hours and we get:
C = 107,512Km / hour
There are 3600 seconds in an hour so:
C = 29.86 km / second
