space, rockets and so on

[ravenhair]

Given that space has no mass, how does a rocket or afterburner work? What is the force acting against?

[incitatus]

Rockets dont apply a force to anything. They eject mass. Try an experiment. Stand on a skateboard with a backpak full of bricks, and throw them one by one in the same direction. Provided you stay on and there isnt too much friction you should move. Rockets hurl large amounts of mass out of the back of the ship. This will push you along even in the absence of something to push against. Action and reaction.