John2020

Hi @pzkpfw, When I read the above text, I didn't understand of what is all about and I just ignored it. Then when I saw the message from the moderator, I realized the misunderstanding. I was referring to my text you quoted with the question you raised. I am not such kind of person you thought I am and I never have such kind of behavior as also it is not in my character. Therefore, I would like to apologize for this misunderstanding. I would suggest to everyone, including myself to keep their cool. It is just a remote discussion after all and nothing should be taken personally. I am a little busy at the moment with some home tasks therefore, I cannot find some time to respond to the questions about the gun and its related physics.

Obviously, this is the wrong analogy. I will explain later.

@Phi for All I was referring to my text that pzkpfw used as reference (quoted) to raise his question. I apologize if it was meant otherwise (my English are not perfect).

See my first post. See paper References section. Moreover, there are daily experiences (e.g. a sudden accelerating rotation of a stranded ball around one's body, starting a motor while being suspended by a strand etc) we actually ignore involving fictitious forces (Centrifugal, Coriolis and Euler) and reactionless behaviors. Yes. Without helical trajectory of the threads, Fig.1-Upper becomes the Fig.1-Lower (the reason I place it there was to demonstrate clearly what is the difference between collinear (action-reaction) and induced inertial forces (reactionless)). See you later in the evening.

I think you don't follow this discussion. The contacts of the thread of the nut ascribe a helix trajectory while nut's CoM is being displaced linearly. See you later

Correction: A paint dot on the thread of the rod will stay where it is after a complete turn. On the other hand, a paint dot on the thread of the nut is displaced to the right along with the nut

The dot stays where it is that means it does not move. What you last quoted is the answer to your question.

There is no recoil because there is no mass transfer in the opposite direction through the translation screw mechanism. Only the nut is being transferred. Mass transfer is allowed only over the translation screw. Consequently, the device can be classified as a reactionless drive.

Fig.1-Upper is supposed to be located somewhere in outer space in absence of gravitational fields. The shortest mathematical proof (although not so nice, I would say) is found in my first post. Take your time. We may continue tomorrow or in the weekend if time permits. It is almost 01.00 am and I have to wake up 05.30 am. Good night! You forgot that in order to have a mass displacement in Fig.1-Upper, the mass being displaced must have threads and translation screw length to cover, something that is not permitted in the opposite direction (while the nut is being displaced to the right) due to the topology of the construction. Good night!

I repeat the justification I shared above: "the only way to trigger an internal reaction in the system is to permit mass transfer in the opposite direction that means the rest of the system, which is impossible. Why is that? Because the rest of the system is hold by the housings that hold the ends of the screw. Consequently, the rest of the system cannot be displaced (as happened with the nut) in the opposite direction.". The above has as result, since the CoM is being accelerated in one direction, the rest of the system will follow at the same direction.

No mass is being displaced in the opposite direction implies no recoil. Check Fig.1-Upper by yourself.

I am addressing now Fig.1-Upper (or what I am trying to share through this thread and through my paper) . There is nothing impeding the acceleration of the nut that implies there is no internal reaction. How can that be? Because, the only way to trigger an internal reaction in the system is to permit mass transfer in the opposite direction that means the rest of the system, which is impossible. Why is that? Because the rest of the system is hold by the housings that hold the ends of the screw. Consequently, the rest of the system cannot be displaced (as happened with the nut).

I have to go to sleep, It is too late (00.25 am). Good night and have a great weekend!

My view on this (or what I am trying to share through this thread and through my paper) is, there is nothing impeding the acceleration of the nut that implies there is no internal reaction. How can that be? Because, the only way to trigger an internal reaction in the system is to permit mass transfer in the opposite direction that means the rest of the system, which is impossible. Why is that? Because the rest of the system is hold by the housings that hold the ends of the screw. Consequently, the rest of the system cannot be displaced (as happened with the nut). You are confusing the proposal of Ghideon with Fig.1-Upper. I am speaking about the Fig.1-Upper. Of course not. In case of Fig.1-Upper, the screw will rotate in the other direction without displacing any kind of mass in that direction. I would suggest to take our attention only to Fig.1-Upper, otherwise many misunderstandings and confusing statements arise and makes this discussion difficult to follow.

But in Fig.1-Upper we have the ability to accelerate the nut in one direction that implies from the moment it coincides with the whole system CoM, the CoM will change. The question is, is there something that will impede the acceleration of CoM (CoM change will take place whatever the case but its acceleration is the point of interest)? Note: Speaking about CoM and as you also pointed out the same in a previous post of yours, the CoM of the whole coincides with the CoM of the nut. This is what is all about this thread and my paper.

No need for a mathematical description at the moment. Just by checking Fig.1-Upper or the version without the guiding bars, isn't the answer obvious?

I am interested to find the answer in the question:"Now from the action-reaction principle, if the nut is being displayed to the right, what is being displayed in the opposite direction in order to hold Newton's 3rd law? "

No.

Then I apologize. @joigusCould you please tell me what is the answer on the following:"Now from the action-reaction principle, if the nut is being displayed to the right, what is being displayed in the opposite direction in order to hold Newton's 3rd law? "

My description as I admitted about the nut is flawed. However, the threads of the nut follow the topology of an Helix, right?

Yes, but the thread of the nut (contacts) follows a helical trajectory. It is clear the CoM of the nut follows a straight line while rotating and I am not arguing about this. The point in my arguments is not about what the CoM of the nut does, this is perfectly clear. I admit my description was really flawed because I had in mind the threads of the nut and not the nut itself, however I used wrongly the nut as following a helical trajectory. Anyway, could you tell me what is the answer on (5): "Now from the action-reaction principle, if the nut is being displayed to the right, what is being displayed in the opposite direction in order to hold Newton's 3rd law? "

Let us ignore (b) and just take our attention to (a). Please allow me to ask you the following: 1.Do the threads of the nut follow a helical trajectory? Note: screw is fixed not rotating. 2.If (1) is true could we say, because of the translation screw only helical trajectory of the threads is allowed? 3.When the nut evolves around the screw, a linear displacement is taking place, right? 4.Is the translation screw hold between two housings and limited between their space? 5.Now from the action-reaction principle, if the nut is being displayed to the right, what is being displayed in the opposite direction in order to hold Newton's 3rd law? Yes. 1.When a real contact force applies in line with body's CoM then, the body will acquire an acceleration by following rectilinear trajectory. 2.See https://en.wikipedia.org/wiki/Helix

Let us see again my argument in the construction in Fig.1-Upper: a) Remove the guiding bars, keep the screw fixed (not rotating). Apply a torque upon the nut and assume it will be converted to nut displacement (fictitious = not over a linear force). b) See my construction. There instead the space (screw) rotates and the contacts of the nut ascribe a helix that results in an induced motion of the nut that is essentially based on an helical trajectory.

Yes, I found it and is the following: Those who participate in this discussion think they know better by ignoring of what they see (along with the thread writer(me)) in favor of what is familiar to them and to their company. This has as result to confuse parts of the discussion, eirher on purpose or because they don't follow the discussion (see joigus last question about gravity. This has to do with Ghideon thought experiment and not with my construction). You still don't see where you (all of you) are wrong. Does the helix trajectory has intrinsically what you call linear motion? Otherwise, it would be called just a circle.

Dear @Phi for All I am asking you to close this thread since it has served its purpose and thank you very much so far for your understanding and patience.