John2020

When I wrote "Let us see what comes out of this", I was waiting your analysis and not that I agree in whatever you assume from the beginning. My above reasoning about friction has to do with the following: Having friction or not, based on your drawing motion occurs along the slope that implies a torque force (project upon the slope) must be there, otherwise nut motion cannot be justified at all. You misinterpret/misunderstand my reasoning. I would suggest you to re-read my post. Here is your text "An object moving in a circle at constant speed has a force directed to the center of the circle, perpendicular to the velocity. The reaction force is in the opposite direction (e.g. you pull on a rope, the rope pulls you, the mass swings in a circle.)". The example with the rope doesn't depict the situation with the nut. As a counter argument I wrote we could have a thin threaded cylinder with no inner volume that means there is no mass (void) along the axis of rotation. Consequently, your assertion/example does not apply (is totally wrong) in my case. The same mistake is made by Ghideon analysis that means the torque force pushes the nut along the slope. If you cannot address what I suggested by insisting only on what is familiar to you then please do not label people as crackpots. First think and then apply what you know. What is wrong in your approach is the notion that the action-reaction principle is independent of the direction of the velocity of the objects. In others words, you break/misuse Newton's 3rd law by ignorance.

I have an objection here. If we had friction this would appear along the slope in which the torque force has to overcome in order the nut to advance. This is the point of the misunderstanding, the nut is not being pushed along the guide rails but along the slope in your drawing. Since nut motion is restricted along the axis of rotation of screw by looking directly on the nut, the contact point appears stationary and what moves is the slope itself along the inclination of the slope.

But in our case the force directed to the center of the circle is not a contact force. For example the screw could have threads but empty inner volume (like a cylinder with threads imprinted on its surface). This is also the reason the path I mentioned above is crucial because only contact forces are relevant to the action-reaction principle along with the direction of the velocity that must comply with it. 00:14 (UTC), Saturday 17 October 2020

How then the action-reaction principle and the momentum conservation applies when the force and the velocity don't have to be in the same direction? It is a contradiction.

OK. Let us see what comes next.

I think so. OK, go ahead. I have to go to sleep. It is about 01.30 am. Post your solution and we will discuss it tomorrow, OK? Good night everybody!

OK. The action-reaction pair (normal forces) in the details analysis are expected to be perpendicular to the inclination of the thread. Right?

I repeat it because none replied to it. The crankshaft mechanism will result to a real linear motion of the nut that allows a collinear reaction, in other words there the Newton's 3rd law and the conservation of momentum follow each other. In the case of the translation screw, on mass displacement (coming not from a real rectilinear force) the reaction is just the rotation of the screw. No mass transfer is evident with the same mechanism in the other direction. From the moment the path is not linear but dictated by the helical topology of the screw threads then, any reaction should comply with this limitation (path). It implies you cannot have linear reaction (in contrast when the mechanism is a crankshaft) along the axis of rotation. I answer on this with the post above this one. See:

It will happen as you expect if and only if we replace the translation mechanism with a crankshaft. In this case we will have recoil. See my reply below:

I am not arguing about the incline and the action-reaction forces that appear. I am arguing about the whole that means on nut displacement, the screw turns without being able to transfer mass to the other direction. Doesn't this make sense? But in our case we have conversion and not plus kinetic energy. We have rotational to kinetic energy where the latter is not caused by a real force.

Thanks for the reply. Speaking about the "hot", I see badge icon writing hot, I assume because of the currently many replies. That's good!

The required shaped is the helix for the trajectory of the threads contacts. Proceed with your proposal and make a complete analysis if you like. Let us see what may come out of this. It is not a point but how you handle this problem. The mistake according to my view is that you (and all others) assume the nut has additionally a kinetic energy or a real momentum, which is not true. Again, none replied to what I shared about the crankshaft. Replacing the mechanism with a crankshaft then we come to your words (Newton's 3rd law). See my reply about the gun where there I justify where is the problem in your approach about the construction in Fig.1-Upper as also I introduce a counter example with a crankshaft:

When researchers claim about "action-reaction symmetry breaking", it cannot be irrelevant then something is going on. Regarding my example, it is another story and has to be faced as a classical mechanics problem. I agree. May I ask you something? Why this thread is so hot and it is not shutted down from the moment, one says "I am ignorant" the other "I have no knowledge of the basics" etc? Could you please clarify this to me? Last time the moderator close the thread because he said I couldn't support it. Am I now supporting it or do I have to start laughing? No. Please tell me, you are the expert along with all others. Observation + Intuition I explained myself regarding Newton's laws and that was my view. Everyone knows that in case of Newton's 3rd law, it holds only when we have a collinear pair. Don't you agree?

I just picked an integer number as minimum. Use 1.9 laps no problem (I suppose).

I think it would be better to have two laps, otherwise the displacement may not manifest. I just would like to mention we need as minimum two laps in order to demonstrate the displacement of the nut. Sorry that was wrong what I said about more laps more momentum. I confused it with something else in the construction.

Well for the theoretical analysis I assume just one lap would be enough. Practically, more laps leads to more momentum since the nut is being accelerated caused by the non-constant magnitude couple (F_A and F_A').

I am not making predictions contrary to a lot of physics. As I mention in my paper there are other disciplines in physics e.g. statistical mechanics, optics etc claiming the breaking of action-reaction symmetry. Check the References of the paper as also google "action-reaction symmetry breaking" or "violations of Newton's 3rd law", which are very bold statements. What I say is since there are experimental results that show a disagreement with the momentum conservation and Newton's 3rd law then why shouldn't this effect appear in classical mechanics, too? Something has been overlooked in classical mechanics and this thread is an attempt to point this out (in a poor and not satisfactory way as I see from your reactions. I accept it.) I assume when the helix angle becomes large enough by making the trajectory almost linear then, linear effects will dominate and less the other stuff I presented above. Ghideon, I opened this thread and I placed a link to my paper in the signature. So people who would read a couple of lines in the presentation of this thread and think (from what they know by respecting what they know without doubting) they know better then this is ridiculous according to them. Normally those people shouldn't participate or in the extreme case the thread should be closed (as they do in Nasa Space Flight Forums. I tried a couple of times there lately. They didn't even let me to develop my arguments. On the other hand, I am very happy this forum gave me the freedom to speak and I really appreciate it.) Can someone tell me why this thread is so hot by the way? Why the moderators didn't flip the switch?

The non-constant magnitude of the couple (F_A and F_A') now upon the nut (according to your example). Assuming the counter torque will affect just the bolt (We put aside (which is correct) the frame of the construction rotation due to the counter torque. I have to fix this.) then although the bolt is fixed (not rotating) the angular momentum conservation still holds. The same effect is expected that is acceleration of the nut without causing a linear real reaction will result in the redeployment of the CoM (assuming the CoM of the nut coincides with that of the construction as a whole) and acceleration of the system.

Is that you think, too? Well done.

You are overreacting. I wonder why you participate in this discussion if you believe I am ignorant. Do you know which fictitious force could mimic a rectilinear real force? This is all about Fig.1-Upper and the title of the paper is to the point. Why are you still here, then?

Fictitious are by nature inertial forces. By"fictitious inertial forces" I point to the fact that fictitious force are inertial by nature. The word "fictitious" does sit well on my understanding and this is the reason I use additionally the "inertial" definition. I should avoid it also in my paper because as you say it sounds as made up. It does not make predictions contrary to Newton's laws. This is assumed by all physicists, however the truth is that Newton's laws apply just when we have real collinear forces. As you know better than me, Newton's laws do not apply to spinning objects. That is all!

Good point. I have to improve the analysis and to re-write the first part of the paper. There are no new laws introduced, just a configuration that appears to not behave as most would expect (again expected according to Newton's 3rd law where according to my view comes from an incorrect analysis of the problem).

I used "Newton's 3rd law" in brackets in order to point to an expectation that is incorrect by analysis. I mean, one cannot expect reaction when deal with inertial forces (fictitious). That is all I wanted to say.

The Author uses classical mechanics as reference because he (along with the mainstream) or any other research attempt has never demonstrated a device to circumvent (in those paper they are making bolder statements that you don^t address, they speak about "violations of Newton's 3rd law and breaking of action-reaction symmetry" that is totally wrong. I make this mistake also in the Introduction (only) in my paper.). One cannot violated Newton's 3rd law but circumvent it using Inertial forces (fictitious), according to my view. Their experiment describes optical pulses that achieve the above in a controllable way. There is no runaway effect in their claims as also in my own. You misinterpret the situation.

The problem with the gun is not the rotation but the use of propellant that implies a real linear force is exerted upon the exhaust of the bullet outwards (action force over the ejected gas) that results in a reaction force pushing the bullet forward. Here clearly applies Newton's third law. However, another action-reaction event is taking place while the projectile and the ejected gas are still in the barrel chamber. In this case, the momentum of the gases is transferred towards the gun, resulting in its recoil. In a few words, we have a case where the momentum conservation follows Newton's 3rd law. Now let's come to the construction of Fig.1-Upper. In the ideal case (as I address it in my paper), we have 100% conversion of angular momentum to displacement, in which displacement is developed while the contacts of the threads ascribe a helix motion by keeping the nut's CoM along the axis of rotation. Then, while the threads of the screw rotate clockwise then due to the conservation of angular momentum, the contacts of the nut's threads evolve counterclockwise following a helix trajectory. Consequently, the mechanism of motion is attributed just to the conservation of angular momentum and not additionally due to a linear momentum because the appearing linear momentum is not real (it does not come from a rectilinear force but through a conversion mechanism that keeps the helix trajectory of nut's thread contacts). It would be a nut real linear momentum if the translation mechanism was a flywheel of a crankshaft. In a crankshaft we may have conversion from linear to rotational and vice versa. When we replace the mechanism in Fig.1-Upper with a crankshaft and we attach on the linear motion part the nut, this will result in real linear momentum (the contacts of the threads of the nut will follow a rectilinear and not a helix trajectory) to the right that will result in a recoil upon the rest of the system. See: https://en.wikipedia.org/wiki/Crankshaft (replace the cylinder of the piston with the nut and the translation screw with the flywheel. https://www.nature.com/articles/nphys2777 (Ref. Nr.9). Check this one. I am not an expert in all these disciplines, however from the search I did I chose those that are related to the subject. As you said may be there is a reference that does not fit to the subject. Well, I did my best, however as you see there is research on this subject and didn't popup just out of my head. No, because Newton's laws apply everywhere as long as the interactions are rectilinear. When inertial forces come additionally into play then, there could be situations where a reaction force (based on Newton's 3rd law) will not manifest because the inertial forces are by nature, reactionless. No, as far as I am aware of except in one patent I found recently on the web that uses a linear actuator to control the movement and velocity of an object in outer space: https://patents.google.com/patent/WO2017070106A1/en Moreover, I have a document in PDF that speaks about this invention and its earth-like application where this idea came from. I have to search where I put it. See you later.