A recoil only occurs when you fire a gun and a bullet leaves the gun. It is a short lived force created by the ejected bullet. When the bullet has left the gun the force of the bullet on the gun is 0. The air friction force acting on the bullet cannot push the bullet back into the gun (as suggested by sceppy).Flabbergasted wrote:
I think Heiwa is trying to say that the initial recoil is simultaneous with the opening of the nozzle, and so it is not really dependent on what the water does in the air. In fact, it seems to me you cannot come to an agreement about this firehose issue because you are talking about two different stages in the process.
When you allow water to leave a tank, e.g. via a hose, the water ejected applies a force on the hose/tank and this force is there as long as the water leaves the tank. It doesn't matter if the water is ejected into vacuum, air or water. The force acting on the ejected water cannot push the water back into the tank. If the water is ejected into vacuum or space no friction forces will act on the water. Etc, etc.
The gravity force acting on me sitting in front of my PC is about 840 N. Luckily the chair I sit on apply an opposite force af the same magnitude, so I do not fly up or drop down. I cannot see these forces but I am convinced they are there.
The chair applies a force of about 1000 N on the floor but again the floor applies the same force on the chair.
What can the mass of the chair be?