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| electrodacus:
Another example of static vs kinetic / sliding friction Sorry for the low resolution You can see that applied force F1 equals friction force F2 same as it happens in case (a) and so no different from a solid box like in this above example. As soon as slip happens the frictional force drops so here is when the stored energy in the belt can now be used inside the vehicle applied between the vehicle body and output wheel to move the vehicle. If you either remove the slip or energy storage the vehicle can no longer move. But removing energy storage is next to impossible. It can be reduced to the point it no longer works but then you will just select a larger gear ratio and blame the low gear ratio for not working. Changing the gear ratio will not result in a completely different vehicle you just change the force acting on the belt or chain thus influences the amount of stored energy. You can have low force on the belt and large displacement or large force and low displacement (stretch) and you can store the same amount of energy by playing with the ratio of force and displacement. |
| fourfathom:
--- Quote from: electrodacus on February 10, 2023, 06:02:20 pm ---If you either remove the slip or energy storage the vehicle can no longer move. --- End quote --- Interesting, but false, assertion. You constantly return to this claim, but you have provided no plausible proof or demonstration. Others have shown (in many ways) that energy storage is not necessary. Again, explain why this energy cannot be used without storage. Friction / stiction / stretch are minor factors in a properly designed "vehicle", and irrelevant to this discussion. They affect the efficiency, but not the fundamental principle. |
| electrodacus:
--- Quote from: fourfathom on February 10, 2023, 06:35:34 pm --- --- Quote from: electrodacus on February 10, 2023, 06:02:20 pm ---If you either remove the slip or energy storage the vehicle can no longer move. --- End quote --- Interesting, but false, assertion. You constantly return to this claim, but you have provided no plausible proof or demonstration. Others have shown (in many ways) that energy storage is not necessary. Again, explain why this energy cannot be used without storage. Friction / stiction / stretch are minor factors in a properly designed "vehicle", and irrelevant to this discussion. They affect the efficiency, but not the fundamental principle. --- End quote --- A "vehicle" has an internal motor/engine and energy source. While we call this a "vehicle" it is a very special case an nothing more than a locked gearbox. Due to energy storage and stick slip hysteresis it has a very particular and no intuitive behaviour and that is the ability to move against the direction of external applied force. In a "normal vehicle" with an internal engine or motor the force is applied between the vehicle body and output wheel so if a flexible belt is used there you have the stretch of the belt during initial acceleration but then stretch remains constant is not fluctuating between stretch and unstretch multiple times per second as it happens in this vehicle where belt is used as an energy storage device to accelerate the vehicle athens or even hundreds of times per second. There are a few facts that you do not understand: 1) Every action has an equal and opposite reaction. 2) A device (gearbox) can not do force multiplication with only two points of contact for that 3 points are needed. 3) An externally only powered device can not move against the direction of applied force. (when have you ever pushed a box and the box pushed you back further than you pushed the box). And if that ever happened to you it was likely a very elastic box and you were thrown back when you lost traction by the elastic energy that you stored in pushing the super elastic box. |
| cbutlera:
--- Quote from: electrodacus on February 10, 2023, 12:05:06 am ---... The video/video's is not an explanation is a proof that my explanation is correct. It shows the vehicle in case (a) being dragged. That means a large F1 force is applied so large that it can drag the vehicle in the direction F1 is pointing and there is no wheel rotation so basically it acts as a solid object. Relation between F1 and F2 is that F2 = F1 except for the short duration when vehicle is accelerate from zero to a constant speed when F1 = F2 + (m*a) I will love you try and find an alternative explanation that is consistent with what is observed in that video first 15 seconds with the last few seconds showing that vehicle is not faked and that wheels can rotate if the input wheels (the ones on the right) are allowed to slip. ... --- End quote --- I think that I may be making some progress here, but rather than this specific example, I’m trying to understand the analytical method that you are advocating. For me that is much more useful. I have made a list of the key points that I have picked up from what you have written. Am I on the right track here? If you do see any errors, could you correct the text as necessary. 1) Intuition plays a key role in classical mechanics. 2) Before making any calculations, it is vital that the analyst chooses the correct frame of reference in which to perform those calculations. This can only be done through intuition, built up from years of experience. Inexperienced analysts can easily get this step wrong and choose the wrong frame of reference. In which case any conclusions that they draw from subsequent mathematical analysis will be invalid. 3) There are two classes of frames of reference, which are the accelerating and non-accelerating frames of reference. 4) In an accelerating frame of reference, objects within that frame obey Newton’s second law of motion. 5) In a non-accelerating frame of reference, Newton’s second law is not relevant, because nothing is accelerating. In this case, Newton’s third law will apply to every object in that system, so every object in the system will be subject to a net zero balance of forces. In the case of two forces acting on an object they must necessarily be equal and opposite. This is what Newton meant by stating "To every action, there is always opposed an equal reaction”. 6) Some mechanical systems can alternate between being in accelerating and non-accelerating frames of reference. The analyst needs to take great care here to allocate the correct frame of reference to each moment in time. Inexperienced and even many experienced analysts can get this wrong, and is one of the most difficult skills to master. |
| PlainName:
--- Quote from: electrodacus on February 10, 2023, 05:30:49 pm ---What will be a good proof for you ? I can buy two Force newton meter and show forces are equal F1 and F2 ? --- End quote --- Yes, get those meters and show that F1 and F2 are equal. |
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