Earth orbits around the Sun at a speed of about 67,000 miles per hour (107,000 km/hr or nearly 30 km/s). At the same time, Earth spins on its axis at about 1,000 miles per hour (460 m/s or 1,600 km/hr). The acceleration due to gravity 'g' decreases if we go down from the surface of the earth towards its center. As g is proportional to (d)−1, we go up from the surface of earth gα(R+h)−2 and the rotational velocity of the earth is increased gαω.