<P> where K = 8 3 π G (\ displaystyle K = (\ sqrt ((\ frac (8) (3)) \ pi G))) ≈ 2.364 × 10 m kg s </P> <P> The escape velocity relative to the surface of a rotating body depends on direction in which the escaping body travels . For example, as the Earth's rotational velocity is 465 m / s at the equator, a rocket launched tangentially from the Earth's equator to the east requires an initial velocity of about 10.735 km / s relative to Earth to escape whereas a rocket launched tangentially from the Earth's equator to the west requires an initial velocity of about 11.665 km / s relative to Earth . The surface velocity decreases with the cosine of the geographic latitude, so space launch facilities are often located as close to the equator as feasible, e.g. the American Cape Canaveral (latitude 28 ° 28' N) and the French Guiana Space Centre (latitude 5 ° 14' N). </P> <P> In most situations it is impractical to achieve escape velocity almost instantly, because of the acceleration implied, and also because if there is an atmosphere the hypersonic speeds involved (on Earth a speed of 11.2 km / s, or 40,320 km / h) would cause most objects to burn up due to aerodynamic heating or be torn apart by atmospheric drag . For an actual escape orbit, a spacecraft will accelerate steadily out of the atmosphere until it reaches the escape velocity appropriate for its altitude (which will be less than on the surface). In many cases, the spacecraft may be first placed in a parking orbit (e.g. a low Earth orbit, LEO, at 160--2,000 km) and then accelerated to the escape velocity at that altitude, which will be slightly lower (about 11.0 km / s at a LEO of 200 km). The required additional change in speed, however, is far less because the spacecraft already has significant orbital velocity (in low Earth orbit speed is approximately 7.8 km / s, or 28,080 km / h). </P> <P> The escape velocity at a given height is 2 (\ displaystyle (\ sqrt (2))) times the speed in a circular orbit at the same height, (compare this with the velocity equation in circular orbit). This corresponds to the fact that the potential energy with respect to infinity of an object in such an orbit is minus two times its kinetic energy, while to escape the sum of potential and kinetic energy needs to be at least zero . The velocity corresponding to the circular orbit is sometimes called the first cosmic velocity, whereas in this context the escape velocity is referred to as the second cosmic velocity . </P>

What is the sound velocity on the moon