How does propulsion work in space?

Question

i am very sure everyone is aware of newtons law action and reaction are equal but opposite in direction, so i have always found it very difficult to understand how does this work in space where there is nothing to act against. i.e you cannot swim in space and in one of the startrek episodes i saw they come accross a creature like whales that propell themselves as they are swiming, absurd!. But can anyone please solve this for me thankyou.
So back to the question how does jet propusion work in space.

Answer 1

Conservation of momentum:

You propel yourself by throwing material in the direction opposite your movement.

This is why until we figure out a better way to propulse ourselves in space, it will remain unattainable. It extremely clumsy to b carrying all this weight just to be able to throw it away. Check out this site for a great discussion about "vacuum propellers":

http://www.fourmilab.ch/documents/vprop/

Answer 2

You're right that you cannot swim in outer space. However rocket propulsion doesn't work on the method of swimming. Newton's third law explains everything and there is no need to push on anything. You've probably noticed that if you push someone of equal size, you both get push away from each other. If you push a small kid, he will go flying back the most. If you bush a really big dude, mostly you get pushed backward. Now suppose you were floating in space and you chucked a rock to the left, you would also move to the right with the same momentum as the rock is moving to the left. If you chucked a small rock, the rock would move to the left really fast and you would move to the right really slowly. If you pushed on a really big asteroid, the asteroid would move slowly to the left and you would move quickly to the right. The rocket is the same situation, only it is chucking lots of particles of gas, as opposed to a rock.

Answer 3

This Newton's law still works in space. Action blasts against the front of the space vehicle, reaction blows very far out into space.

Don't think of the reaction as pushing against something like air. Rather, it is like an explosion blasting out in all directions. In the "forward" direction it pushes against the rocket. In the opposite direction it goes forever into space.

Answer 4

Stand on a skate board holding a cement block. Throw the cement block away from you as hard as you can. You will move in the opposite direction. The important observation is that you start to move backwards before the block hits anything. The block doesn't need to hit anything to send you in the opposite direction. You are pushing against the block.

Answer 5

It isn't necessary to have any matter to thrust against, propulsion is caused by what ever you expel be it air, water, particles of light, sound waves or rocket exhaust which all cause an opposite reaction ( some stronger than others). ie Newtons law.

Answer 6

it's still newtonns law, think of the force called recoil in fireing a gun. it do's not need an atmosfer to work against, it reacts against it's self, hope thats some help, fire fox