text: who can explain the physics of rocket propulsion to me?   you are talking about newton's law of motion #3. it says for every action there is an equal and opposite reaction. if you shoot a rifle you feel the kick, right? the rifle pushes the bullet and the bullet pushes the rifle(back into your arm). with a rocket: the rocket pushes the gas exhaust out the rear and the gas exhaust pushes the rocket forward. because the gas is lighter is goes faster but the net result is the rocket goes forward.