Well, first thing, I am new to this forum and it looks pretty good and I'm looking forward to reading more from it and post more questions. Well rocket propeling (or anything that uses some material to propel up when shooting it down) seems pretty straight forward at first, you have some gas and make a combustion putting a force downwards thus pushing the rocket upwards and it is explained by Newton's Third Law. Now the thing that I don't understand, for example, when you throw a ball against the ground it pushes the ground downwards with a force and then the ground pushes the ball upwards with an equivalent and opposite force making it go up and it is clear that the ground is making the ball go up again while in a rocket you are pushing down through a combustion of gas, you are like "throwing" millions of particles downwards (this interpretation may not be correct) making a force to the ground, but what exactly is pushing the rocket upwards? In my head it is something like this, you are pushing lots of particles into the ground or the are or whatever and once these particles are released they are "free" from the rocket and they don't have anything to do with it. So, is it these particles that really are related to the rocket that push it upwards? Is it the air? What is it? Sorry for any bad interpretation of events, I just want to know what is happening exactly and I don't have much idea about it, in the future I'd like to study aerospace engineering and learn a lot more about it. Thanks in advance to everyone.