Basics of Flight Operation
Now that we have seen the laws of physics, we may proceed further and take our first step towards space travel. As we have seen in the Universal law of gravity, there exists a force of attraction between any two bodies in the universe. Bigger the mass of the bodies, bigger is the force of attraction. So, when any body attempts to break apart from the gravitational field of earth, it experiences a humungous force which pulls it back to earth's surface.
In order to resist this force, the body must be traveling with a suitable velocity. These velocities differ on the basis of whether the body attempts to leave earth and go into space or whether it aims to orbit earth.
These velocities, respectively, are: