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There seems little point in discussing this further with SuS until he has answered my question: at what point, during its ascent through the atmopsphere, has he observed the efficiency of a rocket to decrease?Science is begins with data, not conjecture or analogy, and this is a science forum.
SteinUntStein seems to be one of a growing number of 'skeptics' who don't understand the application of Newton's Laws in certain situations. For example, this painful thread on CluesForum. There seems to be an associated conspiracy theory about NASA...
The problem with applying Newton’s 3rd is that the rocket’s propellant does not generate force in a vacuum according to the laws of physics and chemistry. If the force of the propellant is 0 then Newton’s 3rd states that Force on Rocket=-Force of Gas.If Force of Gas = 0 the rocket does not move.
Short answer: Yes a gun recoils in space. No, the analogy does not apply to rockets.Longer version: Shooting a gun in space would happen theoretically as follows: pressurized gas accelerates the bullet through the barrel until the bullet leaves the muzzle. At that point the gas that was pushing the bullet escapes without doing any more work i.e. via free expansion. The energy of the bullet (its momentum) travels with the bullet and the gun recoils by principle of conservation of momentum.The gun analogy does not apply to a NASA-type space rocket as their pressurized gas escapes without doing any work at all. A NASA rocket is a gun without a bullet.