Tag Info

Hot answers tagged

6

First: what frequency should you hit? There are many, many different factors at play in determining the natural frequency of an object I know from experience. These are (not limited to): Thickness, density, elasticity modulus (you'll need two of those, e.g. Young's Modulus and Poisson Ratio), and of course shape. I'm not aware of any papers publishing a ...


4

For conventional wheels (32 spoke), the answer is 0% compression, 100% tension. This is why it is possible to have spokes that are no more than wires - in fact, bicycle wheels are called "wire wheels" (see the wiki article) What is clear from that article: spokes are under tension, and provide "suspension" of the load from the top rim (see for example ...


3

There are just two requirements, 1) correct frequency, and 2) sufficient amplitude. The correct frequency is, the resonant frequency of the glass cup (pane, cube, etc.). You will know you have sufficient amplitude, when the glass breaks! Both requirements will vary, depending on the material, shape, dimensions of the object, and other variables. If you ...


2

Absorption and refraction indices are the real and imaginary parts of the propagation constant for a medium. This means, given certain mild assumptions on the material's physics, they are the real and imaginary parts of a meromorphic (holomorphic with poles) function of the complex frequency that is holomorphic in the right half plane. They are therefore ...


2

It is an edge dislocation. Compare: to: TEM tracks dislocations in graphene Notice that the yellow loops have 5 and 7 edges, respectively, compared to the usual six.


2

Here's a quick and dirty approximation based on some values reported in Wikipedia: Wikipedia lists the ultimate tensile strength of a carbon nanotube as 63,000 MPa, but in a footnote proposes a "theoretical limit of 300 GPa" for multi-walled nanotubes. Wikipedia also mentions "most single-walled nanotubes (SWNTs) have a diameter of close to 1 nanometer." ...


2

They write that capacity is still half of that of lithium ion batteries, although this can probably be improved. However, this does look like a real breakthrough.


1

The answer depends on the size of the tire, the pressure to which you inflate it, and how much deformation you are willing to tolerate. Just to illustrate, I will take a road ("racing") bike as an example - using rough numbers so you see how the math is done. The tire might be just 20 mm wide, and inflated to 8 bar. Adding weight to the tire will barely ...


1

It's kind of like "material memory." Wool is pretty kinky originally (as sheared), and the production processes pull the strands straight. Hot washing allows the material to revert to a tightly-wound config, which reduces the external dimensions, aka "shrinking."


1

Any structure that leads to a high Q system (the glass) will work and the trick is precisely matching the resonant (natural frequency ). By mounting the glass in a clamp that dissipates energy at a lesser rate than the sound energy that feeds it, the glass is doomed regardless of thickness or lack of imperfections. If the rate of energy input exceeds the ...


1

If you cut something by pushing a blade directly into it, here's what happens: On first contact of blade with material, only the very thin edge of the blade is touching the material, the force per unit area is very high, and the blade cleaves the material very easily. That's why it's almost trivially easy to make score marks in things like aluminum using a ...


1

A TIG electrode needs to have the following properties: initiate an arc easily live long You use tungsten as the main material, you get the high melting point and longevity of the second point. However, the work function of tungsten is very high: 4.3 - 5.2 eV. By contrast, thorium has a work function of 3.4 eV, and has itself quite a high melting point ...



Only top voted, non community-wiki answers of a minimum length are eligible