Constants Definition and 486 Threads

How is the permittivity of free space, \epsilon_0, and the magnetic permeability in vacuum, \mu_o, measured? Thanks

Before we differentiate, we must know whether a variable in that expression represents a constant or variable, correct? For example, if we have the function, f(x) = r^3 x^2 f'(x) = \frac{d}{{dx}}\left[ {r^3 x^2 } \right] (1) Now if r represents a variable then, f'(x) = r^3 \cdot...

What a tensor is .? I have found a text in my book that says that the electric and magnetic constants are tensors.. Do u have something in mind? Thx a lot

To determine the spring constant, k, in a static experiment (i.e. suspending weights from a spring) we use the following expression; k = (mass x gravity) / extension But what if I was on the Moon (where gravity is 1/6 that of Earth) or in part of space where there is zero gravity? The...

Hello, I have the following equation \int \!v{dv}=-{\it GM}\,\int \!{y}^{-2}{dy}\]} Integrating I get... \[\frac{1}{2}v ^{2}+C _{1}=-GM\essdot\left(-\frac{1}{y }+C _{2}\right)\]} Now how do I go from what I have above to this v ^{2}=2{\it GM} \left(\frac{1}{y }\right)+C \]} How it is...

I wanted to find the dielectric constant of different materials placed in a parallel plate capacitor using the equation: K = \frac{E_{dielectric}}{E_{original}} Where E = \frac{V}{d} I would use sensors connected to a computer to measure the voltage and i could easily measure the...

I am stumped... here is the problem: Solve the DE using the following: L and R are constants L\frac{di}{dt} + Ri = E(t) i(0) = i_0 E(t) = E_0*sin(wt) Here is my work so far: I got the integrating factor to become e^{Rt/L}. But now: \frac{d(e^{\frac{Rt}{L}}*i)}{dt} =...

this is just a general question, one that keeps coming up everytime i take a test or quiz. I understand that the derivative of a constant is zero, but I don't understand when you use that zero to multiply or divide in a problem, and when you just ignore that zero. For example x^2/3...

Find the Values of the constants in the following indentities. A(X^2 -1) + B(X - 1) + C = (3x -1)(x +1) AX^2 - A + Bx - B + C = 3x^2 + 3x -x -1 Ok, Is this correct so far? AX^2 = 3x^2 :. A = 3 Is correct ? Bx = 3x = b = 3 ? C = -1 ? I'm sure this is wrong, I just need...

It's not homework, but i think it can make someone think a little. \int\frac{dx}{x} Take it by parts. If you'll be as careless as me you can make a discovery :smile:

What would be the effect of an increase in temp on the rate constant of a) the forward reaction b) reverse reaction and my second Q is..why is it important to specify the temp when giving a value for Ke? Thanks

I was wondering if anyone knew of a database that contains Henry's Law Constants / solubility values for gases in relation to solvents other than water? I can't seem to come across any myself through google but maybe I'm just using the wrong search strings. In specific, I'm looking for K of...

2 Questions, pretty stumped on both. A meter stick is hung at its center from a thin wire (see part (a) of the figure below). Meter stick is hanging from a string, and being "rotated clockwise. It is twisted and oscillates with a period of 6.18 s. The meter stick is sawed off to a...

I'm taking my 3rd quarter on phys. in college right now (heat, sound, optics, & fluids this quarter), and I've noticed that neither here nor in high school was the knowledge of constants and formulae emphasized. Basically, you ask for a formula (as long as it's a simple relationship, not the...

the values of some of the fundamental numerical constants occurring in the standard models of matter and cosmology are considered to be favorable to life and people wonder why they are what they are for example the finestructure constant alpha, why is it around 1/137? for example the...

Hi, I am trying to determine the half lives of two radioisotopes in a neutron activated sample of copper. I have plotted the the ln(activity) vs. time and then used the linest function on excel to get a decay function for the longer half-life by assuming after a certain time, only the longer...

Do the physical laws make up the constants?

A(g) ----> 2B(g) + C(g) <---- When 1.00mol of A is placed in a 4.00L container at temp t, the conventration of C at equilibrium is 0.050mol/L. What is the equilibrium constant for the reaction at temperature t? Also have to Calculate the K(sp) for each of the salts whose solubility...

Hey guys, bit stuck here with this problem I have a differential equation for SHM here in the form x= A cos 10.7t + B sin 10.7t I need to find the constants of integration. w = 10.7 as above I don't have anything other than experimental data Time Second Distance / m 0...

Could anyone here say me what's the constants of van der waals for the Sulfur Hexaflouride (SF6)

Mark-Houwink-Sakurada constants - HELP! Hi! My local libraryes are closed theese days and I need the Mark-Houwink-Sakurada constants ("K" and "a") of poly(methyl metacrylate) in 1,2-dichloroethane urgently! :rolleyes: Does anybody know if i can find them online? where? Or does...

hallo guys. this is my first post( welcome me :-p !). Anyway I'm a freshman taking electrical engineering with a keen interest in physics. anyway my question is this: How do we know that physical constants are really constants. Ok, one way you might say is by assuming, that the...

Can anyone provide a good reference (preferably on-line), or a decent description, of how the fundamental constants of electromagnetism are experimentally determined? I'm talking about constants like the permitivity and permeability of free space. I'm also curious how the unit of charge...

The energy of a spring is the work done on the spring, and for a simple spring with F=-kx the energy may be changed by changing the constant k. In the non-linear case eg F = kx - 4qx^3 we would take the integral to obtain energy. But the question I thought was trivial was, "what values of k...

Hi, I just started a physical chemistry class and we are working on probability theory. The questions I am having a hard time with are as follow: we are given that E is proportional to exp[-E/RT]. It is stated that this is a simple system having only four energy states numbered 1 through 4...

Which of the following will prove not to be a fundamental constant?

What are the 26 constants of the universe? ie. i know gravity, electromagnetism, etc. but what are the values...? :confused: A link or some info would be helpful-thanks :approve:

I would like to hear comments from anyone concerning the below. Honest and critical feedback from qualified individuals is most welcome. Thanks for your reviews! This simple calculation bases the quantum effects of gravity on the electromagnetic frequency across ½ the Compton wavelength of...

Source: Anderson, Principles of Relativity Physics p. 13, prob. 1.4 "Reparametrize the rotation group by taking, as new infinitesimal parameters, ε1 = ε23, ε2 = ε31, and ε3 = ε12 and calculate the structure constants for these parameters." My assumptions: (1) The εij mentioned in...

In a thread in PF's Special and General Relativity ("What if the speed of light was slower") there is a discussion on physical constants, including c. lethe pointed out that there are only 26* truly fundamental constants, and posted a link to a John Baez page with a discussion of these...

What is the purpose of all the Planck's stuff? Planck's length, Planck's energy. And what is Boltzman's constant? On my calculater (PCalc 2 for mac) what is the "Universal Gas" (8.31451)?

A block of mass 12.0 kg slides from rest down a frictionless 37.0 degree incline and is stopped by a strong spring with k=3.50e4 N/m. The block slides 3.00 m from the point of release to the point where is comes to a rest against the spring. When the block comes to rest, how far has the spring...

I would dearly like to know what material has the highest relative dielectric constant and how much is it?

I have been playing a bit with the units of coupling constants. Instead of setting c=1, h=1 (natural units) it is interesting to set c=1 but still to keep h explicit in the formulae. You may know that in natural units there is a basic difference between electromagnetism and gravity, namely...

Is there anywhere I can get a decent print out of the most predominanent constants and equations?

Some people try to memorize the digits of Pi, but why do they do it ? They say that first of all some day you may use all those digits, and secondly it helps you train your memory. I tried, i memorized the first 120 digits, then i got bored ! So, do you people think that memorizing some...