swansont Posted September 1, 2009 Share Posted September 1, 2009 For example, if apply these force separately then part of force need for translation movement and another part for rotation movement. If apply same value of initial forces for both movements then rod will have const translation velocity plus depended on applied radius angular velocity. But sum of forces values is doubling initial value. This is normal simulator behavior on wrong classical mechanics model. This is from real world: According to a JPL spokesman, every maneuver intended to dump momentum added a velocity error of about 0.001 meter per second, on a probe that was traveling at a rate of tens of kilometers per second. These deflections themselves were not the problem, but their incorrect modeling was, when the computer was told the spacecraft had received a force of four or five times as great as it really had. [/font'] Oh, for crying out loud. The quote is referring to incorrect modeling due to a unit error, which is obvious if you read the whole section of the statement. http://www.jamesoberg.com/mars/loss.html That's the error in the model, not some underlying problem with translation and rotation mechanics. Link to comment Share on other sites More sharing options...
Bignose Posted September 1, 2009 Share Posted September 1, 2009 Just because a computer program makes results that you don't know how to interpret or seem nonphysical, doesn't mean it is a discovery. The first and foremost determiner of the value of a model is how well does it agree with physical reality. I can write a program wherein the outputted results are very confusing or nonphysical, but it doesn't mean that there is a change in the laws of physics. It means that I wrote a poor program. There is good reason the laws of physics exist in their current form today -- because they have been validated almost innumerable times over and over again. A single glitch in a program is not anywhere a good reason to attempt to overturn the law of physics -- especially ones that seem to be misapplied in this case. Link to comment Share on other sites More sharing options...
ABV Posted September 2, 2009 Author Share Posted September 2, 2009 (edited) Now consider a collection of particles. Some of the forces acting on an individual particle are a result of interactions between the particle and other particles in the system. These are called internal forces. Other forces come from outside the system. So long as the internal forces obey the strong form of Newton's third law, the changes in the total linear and angular momentum of the collection of particles are given by [math]\aligned \dot{\mathbf p}_{\text{tot}} &= \sum_i \mathbf F_{\text{ext},i} \\ \dot{\mathbf L}_{\text{tot}} &= \sum_i \mathbf r_i \times \mathbf F_{\text{ext},i} \endaligned[/math] The external forces are the only things that change the collection's linear and angular momentum, and each external force contributes to the change in both linear and angular momentum. Finally, consider a solid body. A solid body is just a special kind of collection of particles. I've given the equations of motion many times. You can find these in previous posts. You can find the derivations in any college level classical mechanics text. Read a physics text. Take a physics class. You do not know physics, yet, and until you do all you are accomplishing is making a fool out of yourself. D H. Just keep in mind. 2 movements. 2 trajectories. 2 acceleration2. 2 equations. and ONE force for both equations. This force must be split to rotation and translation parts. We do this miscalculation everytime because everybody did same error before. Why? Because standalone translation with rotation movement not included on classical mechanics book yet. Merged post follows: Consecutive posts mergedAnother simulator glitch? Run Working Model and add rod and force into new project. Click Run on toolbar menu button The rod start moving with velocity 1.042. Stop simulation and attach motor into rods center. Torque 0 active t<0.01(IMPORTANT) Click Run on toolbar menu button The rod start rotating with velocity 0 Stop simulation and add circle with force into project. Click Run on toolbar menu button The rod start rotating with velocity 0 After collision the rod start moving. Stop simulation. Remove motor (Open properties windows. Select motor and click "Edit->Delete" submenu button) Change circle position. Click Run on toolbar menu button The rod and circle start moving with velocity 1.042 on opposite directions. After collision the rod and circle are changing directions. ==== Any comments? Merged post follows: Consecutive posts mergedOh, for crying out loud. The quote is referring to incorrect modeling due to a unit error, which is obvious if you read the whole section of the statement.http://www.jamesoberg.com/mars/loss.html That's the error in the model, not some underlying problem with translation and rotation mechanics. The problem starts from speceship inbalance. The units problem is just a component which is multiply error. Edited September 2, 2009 by ABV Consecutive posts merged. Link to comment Share on other sites More sharing options...
swansont Posted September 2, 2009 Share Posted September 2, 2009 The problem starts from speceship inbalance. The units problem is just a component which is multiply error. You have provided no evidence that this is the case. In any event, you are merely repeating your claims. Repeating the responses serves no purpose. Closed. Link to comment Share on other sites More sharing options...
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