Quote from: Nick on 10/26/2017 07:10 pmQuote from: chazemz on 10/26/2017 03:12 pmJust so I do not misunderstand you. You are saying that as I move my arms away from my body, my body moves away from my arms and when I move my arms towards my body , my body moves towards my arms. Is that correct?That is absolutely correct. It is somewhat counter-intuitive, because it is at variance with our everyday experience.When you stand on the ground and raise your arms out in front of you, you normally do not detect any movement of your body. That is because friction on the soles of your feet couple you to the planet and so the system that moves back is your body plus the planet. The planet is so much more massive than your arms that the movement is infinitesimal.If you conducted the experiment on a frictionless surface (an air table or ice rink, say) or in space, the effect would be observable if you took care. Your arms account for about 10% of an average body mass, so if you raise your arms out in front of you, you move their centre of mass forward about a foot (half an arm's length). The centre of mass of the rest of your body will move back about one-ninth of that, i.e. just over one inch. The centre of mass of the combined system (arms plus body) won't move at all.(Similarly, your body will move down as you raise your arms - again not observed in everyday experience, because of the forces exerted by the surface of the Earth supporting you) We can now move to the spring. As I pull the spring away from me and stretch it, the spring will resist and apply a force against the movement of my arms and my body.So does my body still move backwards (and if so by how much), applying a ever greater force on the spring and vice versa or is its movement hampered by the increasing potential energy of the spring?
Quote from: chazemz on 10/26/2017 03:12 pmJust so I do not misunderstand you. You are saying that as I move my arms away from my body, my body moves away from my arms and when I move my arms towards my body , my body moves towards my arms. Is that correct?That is absolutely correct. It is somewhat counter-intuitive, because it is at variance with our everyday experience.When you stand on the ground and raise your arms out in front of you, you normally do not detect any movement of your body. That is because friction on the soles of your feet couple you to the planet and so the system that moves back is your body plus the planet. The planet is so much more massive than your arms that the movement is infinitesimal.If you conducted the experiment on a frictionless surface (an air table or ice rink, say) or in space, the effect would be observable if you took care. Your arms account for about 10% of an average body mass, so if you raise your arms out in front of you, you move their centre of mass forward about a foot (half an arm's length). The centre of mass of the rest of your body will move back about one-ninth of that, i.e. just over one inch. The centre of mass of the combined system (arms plus body) won't move at all.(Similarly, your body will move down as you raise your arms - again not observed in everyday experience, because of the forces exerted by the surface of the Earth supporting you)
Just so I do not misunderstand you. You are saying that as I move my arms away from my body, my body moves away from my arms and when I move my arms towards my body , my body moves towards my arms. Is that correct?
Quote from: chazemz on 10/27/2017 09:21 amQuote from: Nick on 10/26/2017 07:10 pmQuote from: chazemz on 10/26/2017 03:12 pmJust so I do not misunderstand you. You are saying that as I move my arms away from my body, my body moves away from my arms and when I move my arms towards my body , my body moves towards my arms. Is that correct?That is absolutely correct. It is somewhat counter-intuitive, because it is at variance with our everyday experience.When you stand on the ground and raise your arms out in front of you, you normally do not detect any movement of your body. That is because friction on the soles of your feet couple you to the planet and so the system that moves back is your body plus the planet. The planet is so much more massive than your arms that the movement is infinitesimal.If you conducted the experiment on a frictionless surface (an air table or ice rink, say) or in space, the effect would be observable if you took care. Your arms account for about 10% of an average body mass, so if you raise your arms out in front of you, you move their centre of mass forward about a foot (half an arm's length). The centre of mass of the rest of your body will move back about one-ninth of that, i.e. just over one inch. The centre of mass of the combined system (arms plus body) won't move at all.(Similarly, your body will move down as you raise your arms - again not observed in everyday experience, because of the forces exerted by the surface of the Earth supporting you) We can now move to the spring. As I pull the spring away from me and stretch it, the spring will resist and apply a force against the movement of my arms and my body.So does my body still move backwards (and if so by how much), applying a ever greater force on the spring and vice versa or is its movement hampered by the increasing potential energy of the spring?Your body will move backwards more. Now the mass of your arms plus the mass of the spring is extended forward, so your body moves backwards more to compensate. For simplicity, assuming the mass of the spring plus the mass of your arms equals 20% of the total mass, using the rest of the same numbers that Nick did means your body would move backwards a bit more than 2 inches.One thing to keep in mind is that the forces between your hands and one end of the spring are equal and opposite. The forces between the other end of your spring and where it is attached to you are equal and opposite. There is no rule stating that the force on one end of the spring is equal and opposite to the force on the other end of the spring. In fact these have to be unequal at some point to accelerate the center of mass of the spring away from your chest.Intro physics textbooks discussing systems including springs assume massless springs so that the spring itself does not have to be accelerated which is a very good approximation in many practical cases. If we assume the spring in this case is very light compared to your body, then we just get the same final result as without the spring.Note that I did not need to mention energy in this description. It is irrelevant at this point and we can move on to discussing energy once it is not going to just add more confusion.
So, I hold my body in position as I extend my arms.
If I free my body and bring my arms toward me I can transfer the momentum of my body onto another object without the need for me push against anything?
Quote from: chazemz on 10/27/2017 03:51 pmSo, I hold my body in position as I extend my arms.How do you intend to hold your body in position?There is no way to truly do so, except by moving something else in the direction your body would have moved.Quote from: chazemz on 10/27/2017 03:51 pmIf I free my body and bring my arms toward me I can transfer the momentum of my body onto another object without the need for me push against anything?It is unclear what you are trying to say here. Starting from a position with your arms extended and you at rest, pulling your arms towards you will result in your body moving forward slightly ending up stationary with your arms near to your body as we previously discussed. Nothing else happens unless you hit something while making that motion.
So, I hold my body in position as I extend my arms. If I free my body and bring my arms toward me I can transfer the momentum of my body onto another object without the need for me push against anything?
Quote from: meberbs on 10/27/2017 04:11 pmQuote from: chazemz on 10/27/2017 03:51 pmSo, I hold my body in position as I extend my arms.How do you intend to hold your body in position?There is no way to truly do so, except by moving something else in the direction your body would have moved.Quote from: chazemz on 10/27/2017 03:51 pmIf I free my body and bring my arms toward me I can transfer the momentum of my body onto another object without the need for me push against anything?It is unclear what you are trying to say here. Starting from a position with your arms extended and you at rest, pulling your arms towards you will result in your body moving forward slightly ending up stationary with your arms near to your body as we previously discussed. Nothing else happens unless you hit something while making that motion.Substitute my body for the body of the device (stator). Substitute my arms for the field flux lines and read the description again. It would be a good idea to add another magnet onto the belt in the collision scenario of the two counter rotating motors. You are correct read belt instead of body.
Quote from: chazemz on 10/28/2017 09:09 amQuote from: meberbs on 10/27/2017 04:11 pmQuote from: chazemz on 10/27/2017 03:51 pmSo, I hold my body in position as I extend my arms.How do you intend to hold your body in position?There is no way to truly do so, except by moving something else in the direction your body would have moved.Quote from: chazemz on 10/27/2017 03:51 pmIf I free my body and bring my arms toward me I can transfer the momentum of my body onto another object without the need for me push against anything?It is unclear what you are trying to say here. Starting from a position with your arms extended and you at rest, pulling your arms towards you will result in your body moving forward slightly ending up stationary with your arms near to your body as we previously discussed. Nothing else happens unless you hit something while making that motion.Substitute my body for the body of the device (stator). Substitute my arms for the field flux lines and read the description again. It would be a good idea to add another magnet onto the belt in the collision scenario of the two counter rotating motors. You are correct read belt instead of body.I cannot make those substitutions, because they don't make sense. At a basic level a magnetic field does not have mass, while your arms do. Trying to make an analogy there is flawed. There also isn't an equivalent to extending your arms when it comes to magnetic fields.Also, you seem to be switching from a linear motion system to a rotating one.You also have to explain what you mean by "hold the body still" You talk a bout a "device" and "collisions" The device you have shown a video of does not even come close to matching your description here (to start with it only has one motor) and the device you previously attempted to describe involving belts and magnets did not seem to be set up in such a way that a collision could occur. I'd ask for a better description, but most of your descriptions seem to assume that the person on the other end is psychic, so I will have to ask for a detailed labelled diagram.Before moving on to this new system, it would be helpful if you acknowledged the previous description that when stretching a spring attached to you by extending your arms, the spring does not change the result other than increasing the mass of what you extend forward to be mass of arms plus string rather than mass of arms.
You have completely missed the plot here. The spring discussion is neither here or there. To expend so much energy to stop, start, stop, start, a millimetre at a time is, in my opinion, about as useful as a chocolate teapot. The point is to use the scenario and the comments made (thank you to everyone who commented) as a platform to hopefully make some meaningful progress.
If it is your desire for me to be in error
On a completely different subject, using electromagnets in the two counter rotating motor, belt scenario, both the collision and push back instances look cautiously promising.
Basic sketch attached, there are numerous variations that can be made ie change position of hull magnets, add more magnets to belts, add a braking zone per cycle etc, etc, etc.
Before we discuss this situation you still haven't answered an important question: Do you understand that in the scenarios described with stretching a spring that is attached to you, you cannot move anywhere at all no matter how much time or effort you put in?
Your belt magnets are part of the same system as the hull magnets. No motion would occur as the belt magnets would push back with an equal amount of force as the hull magnets. It’s the same reason you cannot lift a manhole cover you are standing on.
Quote from: Basto on 10/31/2017 02:53 pmYour belt magnets are part of the same system as the hull magnets. No motion would occur as the belt magnets would push back with an equal amount of force as the hull magnets. It’s the same reason you cannot lift a manhole cover you are standing on. Remember, the belt magnets are moving and the hull magnets are stationary before the collision occurs.
Quote from: Basto on 10/31/2017 02:53 pmYour belt magnets are part of the same system as the hull magnets. No motion would occur as the belt magnets would push back with an equal amount of force as the hull magnets. It’s the same reason you cannot lift a manhole cover you are standing on.We'll, actually you can in principle but probably impossible in practice..... same as skateboarders lifting the board they ride on. But only because both can react against the earth but the principle behind what I think you meant is correct.
Quote from: Bob012345 on 10/31/2017 03:41 pmQuote from: Basto on 10/31/2017 02:53 pmYour belt magnets are part of the same system as the hull magnets. No motion would occur as the belt magnets would push back with an equal amount of force as the hull magnets. It’s the same reason you cannot lift a manhole cover you are standing on.We'll, actually you can in principle but probably impossible in practice..... same as skateboarders lifting the board they ride on. But only because both can react against the earth but the principle behind what I think you meant is correct. When you turn the motors off, nature is in check. It only has one square to move and that is to transfer the momentum to the body.
The belt magnets and the hull magnets are repelling each other so we will have the facing poles as north. I will go through some scenarios soon, mostly with electromagnets and hopefully someone will have some constructive comments.