meta user
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| bio | website | |
|---|---|---|
| location | United States | |
| age | ||
| visits | member for | 2 years, 6 months |
| seen | 16 hours ago | |
| stats | profile views | 305 |
Started programming on a ZX spectrum in the 80's and have moved through Assembly, Turbo Pascal, C++, C#, Fortran. My main area of focus is engineering and scientific computing like numerical methods and 3D graphics.
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Spring damper model does not work very well @Greg, no this formula is for constant acceleration. The OP is talking about a numerical solution where the acceleration changes with position and velocity. |
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Why are some jenga pieces easier to remove than others? @BrandonEnright, I agree as you can see from my comment on the OP. |
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answered | Why are some jenga pieces easier to remove than others? |
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Why are some jenga pieces easier to remove than others? Note that small size changes affect the load distribution among neighboring blocks. |
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Why are some jenga pieces easier to remove than others? For each block, sum of forces equals zero and sum of moments equals zero. That's how you calculate the internal forces. |
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How do determine the equation of motion of slinky? @user24642 Lookup online for multi-mass spring modeling, and maybe it will steer you towards a way of dealing with this. |
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How do determine the equation of motion of slinky? A slinky is a one long beam, with end points contacting the ground and coils clashing. Not en easy problem to deal with in general. |
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Spring oscillations and waves Yes, in valvetrains it the reflected wave in the valve spring that cause surge and loss of contact at high rpm. |
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May 18 |
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Effective mass in Spring-with-mass/mass system Note that in the design of valvetrains, helical springs get the $\frac{1}{3}$ treatment, but beehive springs get a higher ratio. In some cases up to $\frac{1}{2}$. |
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May 18 |
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Effective mass in Spring-with-mass/mass system I have written this but it yields a ratio of $\frac{4}{\pi^2}=0.405$. |
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May 18 |
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Effective mass in Spring-with-mass/mass system I have wondered about the same, and I remember solving this problem a few years back. But how, I do not remember. I also remember that the 1/3 fraction is only valid for low frequencies (< nat. freq.). As the frequencies increase the ratio increases also. |
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May 18 |
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Effective mass in Spring-with-mass/mass system $m' \ddot{x} = \ldots$ is wrong. You cannot take a massive spring and a linear force law. You have to solve a differential equation. |
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May 18 |
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Determine the velocity and acceleration of the vertex $B$ OP says line is $A$ to $D$, therefore it is along $\vec{r}_D-\vec{r}_A$. |
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May 17 |
answered | Static friction force on a block in a tunnel |
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May 17 |
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Static friction force on a block in a tunnel Since when do physical laws not reflect reality? |
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May 17 |
answered | Determine the velocity and acceleration of the vertex $B$ |
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May 17 |
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Determine the velocity and acceleration of the vertex $B$ I usually have it as $\vec{v}_B = \vec{v}_A + \vec{ \omega} \times (\vec{r}_B-\vec{r}_A)$ so I do not get the sign wrong. |
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May 17 |
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Static friction force on a block in a tunnel How are you going to make perfectly flat walls and a perfectly fitting cube. What happens if the temperature drops and now you have a press-fit situation, or the temp rises and you have too much clearance? How are you going to control the interface geometry to make a robust measurement? |
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May 17 |
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Static friction force on a block in a tunnel Can you tilt the tunnel and allow only one wall to be in contact at the time? |
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May 17 |
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Static friction force on a block in a tunnel This is a completely unrealistic situation as you have to consider a) The clearances b) Any tilt of the block c) non-flatness of the walls. The force to unstick the block varies greatly with these factors mentioned. |
