Units of measurement Definition and 20 Threads

Hello. I would like to replicate the plot (a figure) provided in an example. The example is presented in a journal paper and shows the calculation for the inductance of a motor with known torque and angular speed. Below is the figure, and the table of parameters provided in the paper Border...

The original quantity is given in this paper: [reference][1], equations: (31-33-34), where ##a(\eta)= \frac{1}{H\eta}##, so I considered in (1) only the constants which share by dimensions to ##P##. Any help is appreciated! [1]: https://arxiv.org/pdf/hep-th/0703290

I have a table of densities of galaxies : Expected number density of galaxies for photometric survey per unit area and redshift intervals, ##\mathrm{d} N / \mathrm{d} \Omega \mathrm{d} z\left[\mathrm{sr}^{-1}\right]## and the corresponding density of galaxies per ##\operatorname{arcmin}^2## for...

I have a vizier catalog with H-alpha fluxes as logF(Haplha) in units as mW/m^2. See sample data here: http://vizier.cds.unistra.fr/viz-bin/VizieR-3?-source=J/MNRAS/431/2/fluxes How do I convert mW/m^2 to W/m^2/nm or erg/s/cm^2/A? The first entry is logF(Halpha) = -12.03 mW/m^2

Hi, just wondering if the dimension of velocity is m/s that can be described as what distance is passed in a specific time, then how can I describe volt which is kg•m²÷s³÷A? Mass in the area that moved... I can't even imagine. Thanks.

I'm getting the wrong results when using an old, undocumented code and just realized there's a number lurking in it that I can't account for. It's: 0.023901488 and it is multiplied with molar volume and pressure. I have searched for a couple of hours but just can't figure out what the units...

How to transform density unit in natural units $MeV^4$ to SI units $kg/m^3$, Here's my trial: ##MeV^4 = (10^6)^4 ~ eV^4 = 10^{24} ~ eV^4 ##, ## eV = 1.6 * 10^{-19}~ kg~ m^2 / sec^2, ## ##MeV^4 = 10^{24} ~ 1.6^4 * 10^{-40} ~ kg^4 m^8 / sec^8 ## This is not simply ##kg/m^3##! Any help how to...

Can you give details?

Homework Statement Note that this formula (##C=4 \pi \epsilon_0 R##) and the others we have derived for capacitance involve the constant multiplied by a quantity that has the dimensions of a length. Homework Equations ##\epsilon_0## has the following units in SI: $$\frac {C^2} {N \cdot m^2}$$...

I have an acquaintance who maintains that in quantum field theory, primarily the cgs system is used. OK, I know it's not really important, but I was under the impression that everyone had switched to SI. (My book on quantum field theory has very few actual quantities with units outside of GeV...

Despite being a constant, It has both dimensions and a unit, can someone kindly explain why ?

I have been struggling through my physics class this summer (it doesn't help that 5 months worth of material is crammed into 2 months in an online classroom). This site has helped me out a lot, but I am still stumbling through understanding when to use certain equations. When I started reading...

this question is about dimensional analysis involving a number with units and a number with no units, if the question is already answered in another post please redirect me if not here is a simple example, for example, : say i have 2[in]-1. the 1 is dimensionless and the 2 has units of [in]...

Homework Statement At resting, can you breath sufficient air through a tube of 100 cm length and 2 cm radius? normal resting respiration rate: 10 - 20 breaths per minute (3 - 6 seconds per breath) normal resting respiration volume: 0.5 L normal pressure difference in respiration = 1 mmHg =...

I have a question about a seemingly illogical and strange aspect of multiplication and unit conversion that I have never noticed until now. It concerns the issue of finding the area of a square/rectangle when the length and width are expressed as decimals/fractions. Ordinarily, when you find...

I recently come across with an amazing equation of Theory of Everything; I wonder if TOE has been formulated (?) I found this equation on a website, check it out http://www.preposterousuniverse.com/blog/2013/01/04/the-world-of-everyday-experience-in-one-equation/. While seeing briefly this...

I have a very basic questions about units for angular momentum. The measure is in kg m^2/s Angular velocity is in radians/s and therefore radians do not appear in the units. Here is my question, can we leave this in degees/s? Sure its not used but is it wrong? If we are dealing with...

I am talking about length area and volume. As I reason it out in my own mind area (and volume) is based on length and involves 2 random measurements of length that are combined (with multiplication as the device of convention - could any other function be used to work as well and as...

The units of measurement of the SI (System International) are commonly used around the world ·· they form a coherent system usable for a variety of branches of science. But.. there's another coherent metric system that may be a better fit for many applications in chemistry and physics. The...

Hi everybody! Would someone please advise on the following matter. I'm making up a table of railcar operating loads. One of the column includes abbreviated units of measurement such as kN, MN, N/mm2, etc. The question is: How should I title the column? I was thinking about titling it...