To derive the centrifugal acceleration on the equator (i.e. Space rockets from Cape Canaveral need to attain about 8 km/s (in the frame of reference of the non-rotating center of the Earth ) to achieve orbit, so to give them a favorable starting velocity, such rockets are generally launched eastwards. That velocity is directed eastwards and is significantly faster than the speed of sound, which is about 335 m/s. If the equatorial radius of Earth is 6378 kilometers, the circumference comes to 40074 kilometers-slightly more than the 40,000 kilometers supposed to be the pole-to-pole circumference, implied by the definition of 'one meter.' The difference comes because the Earth bulges out at its equator. One important rotating frame is the surface of the Earth, rotating with a period of about 24 hours-more accurately, 23 hrs 56.07 min or 86164 seconds. The reduction of effective gravity by the Earth's rotation
