# Search results

1. ### Is a Psychology degree really considered useless?

If I may introduce another point, I would be careful even when studying for a degree in something you're passionate about not to let yourself get 'burned out'. My wife has her degree in computer animation, but the process (which included the way the school tried to push her and her peers toward...
2. ### Center of Mass of Non-Uniform Rod Using Piecewise-Defined Function?

I have not done this kind of thing before, so this is all new to me. Can you explain some of the steps in the routine method you mentioned so that I can look them up? Someone I know had suggested going through a rather drawn-out process of plotting--inaccurate--points using the shadow of the...
3. ### Center of Mass of Non-Uniform Rod Using Piecewise-Defined Function?

But in order to obtain the equation for a non-uniform rod's linear density, do I not have to take the piecewise function modeling its cross-section, write the equation in unit step notation, take the Laplace transform, and so on?
4. ### Center of Mass of Non-Uniform Rod Using Piecewise-Defined Function?

How would one go about finding the center of mass of a non-uniform rod when its cross-section has been modeling using a piecewise-defined function? For a specific case let's use a drumstick, noting its volume as a sum of half of a sphere (the 'butt' end), a cylinder (the 'shaft'), the majority...
5. ### Can't Find 2D Elastic Modulus Equation

I have tried showing your posts to my Pre-Calculus professor as a 'last ditch' effort (explaining the forum rules beforehand), and after mulling it over even they don't know how to solve for ##r_i##. They did make the concession, though, that its method could be rooted in physics. Way back when...
6. ### Finding Optimal Axis of Rotation with Constraints

What I think I'm trying to find I believe has to do with the 'center of percussion', but it's almost like it's other way around... It's not the point where a force doesn't result in a rotation, but more like a point where a torque doesn't result in a translation (which I'm guessing is the...
7. ### Can't Find 2D Elastic Modulus Equation

The more I work on this the more I wonder if you had accidentally defined ##r_i## twice, as both a radial location and as a radius of its own, because I'm getting frustrated with the problem, and feel as though I can't do anything.
8. ### Can't Find 2D Elastic Modulus Equation

I tried solving for the logarithm and ##r_i## separately, but I still don't feel as if I've gotten any warmer, because by substituting those expressions in it seems I wind up losing ##δ## ... Regarding your expression ##\frac{ln(ξ)}{ξ}## , I know it is equal to ##\frac{ξ'}{ξ}## , but it's...
9. ### Finding Optimal Axis of Rotation with Constraints

I'm hoping to derive a formula which provides the distance from the stick's center of gravity to the pivot point along its length that displays a balance between minimizing the torque needed to achieve a particular angular momentum when traveling through an angle of π/2, and yet also minimizes...
10. ### Finding Optimal Axis of Rotation with Constraints

Here's the Wikipedia article I mentioned: https://en.m.wikipedia.org/wiki/Center_of_percussion
11. ### Finding Optimal Axis of Rotation with Constraints

When playing a percussion instrument with drumsticks there are two main gripping types: "Matched" (where the grip of one hand is the mirror image of the other), and "Traditional" (where the grip, and consequently the motion, of one hand, usually the 'weaker' hand, is transformed from...
12. ### Finding Optimal Axis of Rotation with Constraints

In order to calculate the center of mass of this non-uniform cylinder it becomes necessary to find its volume, followed by its mass (assuming it's isotropic) I honestly had never heard of that term until now, but after reading the cursory explanation on Wikipedia that may be at least close...
13. ### Finding Optimal Axis of Rotation with Constraints

I understand. I could write a piecewise-defined 2-D equation r(x) describing the changing radius from 0 to L, take the indefinite integral, then multiply it by 2π. Vstick = 2π * [integral;0,L] r(x) dx However, I already have this information, and the integral would just result in the exact...
14. ### Finding Optimal Axis of Rotation with Constraints

I really don't have much experience with calculus ( :sarcasm: Hooray! ), but earlier I was reading an introductory article explaining the usefulness of the Lagrange multiplier in dimensional optimization, http://www.slimy.com/~steuard/teaching/tutorials/Lagrange.html and it reminded me that...
15. ### Can't Find 2D Elastic Modulus Equation

Whenever I try to solve for ##r_i## I keep getting stuck with it either 1) both inside and outside a logarithm, as when I started, or 2) when solved for ##r_0##, it is both a coefficient and an exponent of an exponential function.
16. ### Can't Find 2D Elastic Modulus Equation

I was just reading back over Hooke's Law out of a WikiBooks entry called 'Strength of Materials', https://en.m.wikibooks.org/wiki/Strength_of_Materials/Introductory_Concepts and only just remembered reading in the past that Mylar is a class of product called BoPET, or Biaxially-Oriented...
17. ### Can't Find 2D Elastic Modulus Equation

Ahhh, ok. Strength of Materials first. The rim is there to help make sure the force exerted by each tuning bolt is kept as even as possible over the arc length of the circumference it affects. The stronger it is, be it from a stronger material or thicker walls of the rim, the more even it...
18. ### Can't Find 2D Elastic Modulus Equation

What I'm guessing you mean by "combine the two slope equations" is that they should be set as equal to each other, and then solved for ##r_i## so it can be substituted into ##F## to "eliminate" it.
19. ### Predict Digits of Irrational Numbers with Modular Arithmetic Summation?

Ok. I thought that might have been it, but at the same time it felt like it might have been incorrect because I would be using a term of sqrt( x ), similar to y = 2x - | y | ... Ok, so now we have n^(1/m) = floor(n^(1/m)) + (Summation; x=1, (inf)] \frac{(integer(f(x))mod10)}{10x} ... Then...
20. ### Mathematics Notation Question

Would it not be more efficient to write modular functions using the text formatting of logarithms? The modulus would be in subscript after "mod", and the expression to be used would be written after... Ex. modnf(x)
21. ### Predict Digits of Irrational Numbers with Modular Arithmetic Summation?

Would it be possible to write an equation utilizing a summation of a modular function of a Cartesian function, whose degree is dependent upon the index of the root, in that it predicts the digits less than 1 of the root, that when summed equals the computed value sqrt( n )? I already have what...
22. ### Can't Find 2D Elastic Modulus Equation

I just found a free e-Book version of the book called "A Treatise on the Mathematical Theory of Elasticity". Is this what you were referring to? https://books.google.com/books/about/A_Treatise_on_the_Mathematical_Theory_of.html?id=kZIfAQAAMAAJ Also, I just found and downloaded a free PDF...
23. ### Can't Find 2D Elastic Modulus Equation

I understand. I felt nervous asking such a question to begin with, not even remembering the guidelines. If future questions would fall outside of PF guidelines, please let me know. I have--what I think is--a conceptual question. Would it not be reasonable to assume that, shape of the...
24. ### Can't Find 2D Elastic Modulus Equation

Here is a sketch of the apparatus: After a little thought yesterday I realized that, even if still not correct, I could at least somewhat model what you drew earlier, including the distance when the center of the area of contact and the center of the membrane:
25. ### Can't Find 2D Elastic Modulus Equation

I just realized that the diagram you drew earlier doesn't include the distance--if any--between the center of the membrane and the center of the contact area...
26. ### Can't Find 2D Elastic Modulus Equation

Considering this is a circular membrane, meaning it has but one edge, could we not then use something like the surface tension divided by the circumference? Surface tension, at least, is in N/m...
27. ### Can't Find 2D Elastic Modulus Equation

Do you know if the apparatus described above would be able to measure the force per unit area, or would I even be able to compute the force per unit area from the values obtained by such a device? As the second part of my post, my question is if you would be *willing* to do such an analysis. I...
28. ### Can't Find 2D Elastic Modulus Equation

Ok. (Some times I ask a question to at least have asked, no matter how silly it may feel at the time.) Anyway, the variable ##σ_p## for pre-load stress – is it supposed to be the surface tension, radial tension, or neither? I have designs for a physical apparatus so I check an *aspect* of...
29. ### Can't Find 2D Elastic Modulus Equation

I have a question about the pre-load stress, but I don't want to ask until you're done.
30. ### Can't Find 2D Elastic Modulus Equation

Your compliments are well-received, Chet, and I will take them to heart. I am honored.