2005年4月1日 · 3 or 4 years ago, I've had a lot of discussions on sci.physics.research about dimensions, fundamental constants, etc, particularly of [tex] G, c, \hbar, \epsilon_0 [/tex]. first of all, let's not call the Coulomb Force Constant "k" (because i have used it and gotten mixed up in conversation with people who think "k" means the Boltzmann constant).

2025年2月22日 · That is a good question. The key point in the question is that in flat spacetime ##x## is a four-vector so ##g_{\mu\nu}x^\mu k^\nu=\phi## clearly requires that ##k## also be a four-vector. In curved spacetime however ##x## is not a vector. It is an element of a manifold, which lacks the structure of a vector space.

2013年10月6日 · Basically "k" has been given this strange, nonintuitive shape so that deep and fundamental results in electromagnetism look cleaner on the paper [tex]4\pi[/tex] is the surface area of a unit sphere. The "e" is the "vacuum permittivity", closely related to the speed of light in vacuum, "c", through the formula:

2007年6月19日 · I'm trying to find the spring constant 'k' by using the slope of my graph. When I do this I get a huge number so I'm playing with units to bring it down. Homework Equations k = g/slope (g = 980 cm/s^2) The Attempt at a Solution using the info. gathered my k = (980 cm/s^2) / 0.073 = 13520.55 this sounds extremely high.

2013年5月22日 · One good way of defining the cross product is to start with 1)[itex]\vec{i}\times\vec{j}= \vec{k}[/itex] 2)[itex]\vec{j}\times\vec{k}=\vec{i}[/itex]

2010年8月12日 · Basically, it is a unit cell in reciprocal space. There are points of different symmetry in that space/cell, which are usually named by capital letters. As you seem to be interested in graphene, the K point is the point where the conduction and the valence band touch. The geometry of the surfaces around that point is locally conical.

2016年2月26日 · Homework Statement This formula we've been using recently, I don't understand where it comes from. Homework Equations T = 2pi * sqrt(m/k) The Attempt at a Solution Hooke's law: F = -kx E(total) = .5mv^2 + .5kx^2 Circumference of a Circle: C = 2 * pi * r I figure these piece together, but I...

2015年8月6日 · If F=ma and F=−kxThen ma=−kx (by equating the forces.) Which can be also written as ma+kx=0or a+kmx=0Now if x is displacement, differentiating once with respect to time will give you velocity of the spring and then differentiating again with respect to …

2005年11月4日 · The "*" there stands for the "dot product", or "inner product" of the vectors. It is basically an orthogonal proyection; it returns the length of the "shadow" that one vector projects over the other one (where this "shadow" falls perpendicularly to the …

2014年12月29日 · Hi everyone, I have a conceptual question about entropy. I understand perfectly why mathematically the units of entropy are energy per temperature (SI: J / K). However, I would like to better understand the significance of these units. For example, the SI units for speed/velocity are m / s...