im just asking... that makes sense in atmosphere, but in space how does a total vacuum determine/receive exhaust pressure/speed?? how does a total vacuum determine if that craft is doing 3 mph or 30,000 mph??
Newton's Second Law: For every action, there is an equal and opposite reaction.
Blow exhaust out a rocket nozzle at 30,000 MPH (theoretical) and the spacecraft will be propelled to 30,000 MPH, but no more than that.
The only way a spacecraft can go faster is by using the gravity of a planet to slingshot it to higher velocities, which is what NASA uses for exploration of the outer solar system.