Recent content by scoutfai

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    Need help to verify an attempt to explain strain as point property

    Thanks for the enlightenment. Your explanation is way more general than mine. I see your equation and mine equation almost the same form. Can I say I am not wrong? But can I say I am right about my equation and reasoning?
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    Need help to verify an attempt to explain strain as point property

    Recently I review some old text and browse around the internet to read about definition of strain and stress. I come across the following document http://web.mit.edu/emech/dontindex-build/full-text/emechbk_4.pdf Previously I have been facing difficulty trying to come out with an...
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    Ductile material engineering stress-strain curve

    Thanks for the encouragement :blushing: Some follow up questions: (2.1) If plastic deformation is only a kind of permanent deformation, then prior to the yield point, what kind of permanent deformation is taking place? (2.2) I do not have the background on these topics (permanent set and...
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    Ductile material engineering stress-strain curve

    I understand that the engineering stress-strain curve of different material under tension test is different, but for the sake of simplicity the scope of this discussion will be for a general ductile material. If you have to pick a specify example, I think perhaps you can use steel or iron...
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    Comparing pressure of air in a tire installed in a car & a free tire

    Hence, if I was to pump air to a tire but I can only carry a free wheel instead of driving the car to the air pump, says I wish to have 30psi in my tire when it is installed on axle, then I should just directly pump in 30psi instead of a slightly lower pressure (for instance, 29psi) because the...
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    Comparing pressure of air in a tire installed in a car & a free tire

    Imagine an ordinary car wheel with rubber tire, installed in a car axle. So the weight of the car (some of the weight of course, because there are 4 wheels) is pressing on it. Let's denote this pressure of the air in the tire as P_{c}. Now the same wheel (with its rim and tire) remove from...
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    Valve spring in engine, why the closer coil must be down?

    After you had pointed out for me, I agree that question (2) had been answered. As for question (3), I guess the answer you mean is "No, the result and observation are not identical." I agree with this statement for real case. Let's try to bring the analysis to the next level, by...
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    Valve spring in engine, why the closer coil must be down?

    Thanks to Ranger Mike and Q_Goest. Q_Goest you correctly interpreted my intention. Your explanation helps a lot, it now make a lot more senses to me. Let's see will there be any other suggestion on the purpose of the orientation of the valve spring. Nevertheless, Ranger Mike provided...
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    Valve spring in engine, why the closer coil must be down?

    These are more like the function of the uniquely shaped valve spring, but it doesn't explain why the more coil end has to always face down. BTW the spring picture you provides, doesn't look like a typical valve spring of engine, maybe those that I seen are old design. The typical valve spring...
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    Valve spring in engine, why the closer coil must be down?

    In engine, there is valve and the valve spring. If you have ever look at the valve spring before, then you will notice that one end has its coil closer together than the other end. So a valve spring is a kind of progressive spring. In almost all engine repair manual I read, the instruction is...
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    Vector. Is there an inverse of dot and cross product?

    Hence it is still do-able but the answer is never unique and there are infinitely many correct answer. Got it. Yes this is exactly what I mean. I came into a situation where I want to reverse the process then I realize it doesn't seem to be reversible, thus I seek for confirmation.
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    Vector. Is there an inverse of dot and cross product?

    Given the following cross product equation: \vec{A}\times\vec{B}=\vec{C} How to express \vec{A} in term of \vec{B} and \vec{C} (or \vec{B} in term of \vec{A} and \vec{C} ). I think the question I want to ask can also be rephrased as if one was told that a known vector when cross product with...
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    Wave Propagation: Experiences Beyond Equilibrium Position

    You claim that the water surface wave is not a transverse wave. But, how would you explain the phenomena where a stone is dropped onto the surface of a static water surface, upon contact, a circular wave propagating outward? If a very light particle indicator (such as a tiny piece of...
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    Wave Propagation: Experiences Beyond Equilibrium Position

    Hence, the simple surface wave theory must be wrong or inadequate to explain tidal wave, right? Because by observation we knew that when tidal wave strikes, the amplitude is huge but not infinite and the speed is definitely not zero. Your explanation on the particle of water surface wave...
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    Wave Propagation: Experiences Beyond Equilibrium Position

    "water wave is not transverse wave" All right this is new to me. Perhaps in school time the claim that water surface wave is a transverse wave is an approximation (if so, under what condition this approximation becomes good?) Nevertheless, will the particle of such a water surface wave (the...
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