Rocket stages.

[dibble1]

I believe that the enormous speeds that the Saturn V rockets achieved was because as each stage blasted away from the previous one the speed was vastly increased. As space is a vacuum why did this force not have the effect of just pushing the previous stage away and not generating forward motion?
Hope you understand that.

[Milvus]

The only effect that stage separation has is to reduce mass, increasing the thrust/mass ratio, thus increasing acceleration. there is no real push-off effect from the previous stage. Rocket propulsion is governed by Newton's third law of motion "for every action there is an equal and opposite reaction". Therefore as long as the thrust from the rockets is grater than the mass off the rocket then the rocket will move in the opposite direction to thrust. When leaving earth, drag factors such as gravity and atmosphere drag affect the rocket acceleration, when free of earth's gravity then it is almost simple Laws of Motion Physics until another planet/moon comes into play

[dibble1]

Thanks. I think I've got it!

[mibn2cweus]

No point in lugging around an empty fuel tank http://en.wikipedia.org/wiki/Multistage_rocket

[jomifl]

The thrust only has to be greater than the mass (which is approximately equal to it's weight on the earth's surface) of the rocket to enable it to ascend if it is on the earths surface (gravitation 1g). On another planetary body it has to be greater than it's local weight which is determined by the local gravity. In free fall ie. in space any thrust will produce an acceleration in any direction.