It uses large engines and a huge amount of fuel to accelerate the rocket away from earth. The fuel burn pushes out huge amounts of gas, forced out in the opposite direction to the rockets direction...
As we throw a stone vertically up it will go to certain height and fall back towards the earth. This is because the kinetic energy given to the stone gets changed into gravitational potential energy...
Unless a projectile is launched at escape velocity, it cannot leave the earth's gravitational pull. For Earth this means the initial velocity must be about 11.2 km/s (ignoring drag and the launch...