How Does A Rocket Work Very Well In The Vacuum Of Space?

When you blow up a balloon, your breath stretches the skin of the balloon equally in all directions. The gas inside pushes out away from the centre. The push in each direction is matched exactly by an equal force in the opposite direction. It is like two horses of equal strength trying to haul a stone in opposite directions. The stone would not budge. And neither will the balloon. But suppose you remove the string from the mouth of the balloon. This allows the air to rush out in one direction without any trouble at all. It is like cutting the reins of one of the horses, the one tied to the stone will be able to move forward with it. In the case of a balloon, it will go sealing off through the air in opposite direction from the point where the gas is escaping.

This is the principle of a rocket. It is different from a turbo jet or ramjet engine because it does not depend on using air from outside itself. When all the air has escaped from balloon, it will drop to gases, it will stop accelerating. But it does not depend on air to burn its fuel, and it does not heat air to produce thrust. It can operate far above the earth, in the vacuum space. A chemical rocket is filled with materials which combine to produce hot gases at a controlled rate. Sometimes two liquids are used which almost explode as soon as they touch each other. Sometimes the liquid or solid propellant has to be ignited by a spark. But the result is always the same. The gases try to expand in all directions at once, but a nozzle at the bottom of the rocket allows them to escape at one particular point. When they do, the rocket is pushed upward from the inside.