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What is the key difference between SI and MKS units?

The history section of the SI page on Wikipedia covers the history quite well. Basically, MKS came before SI. It was later upgraded to include electromagnetic units, creating a new system called ...
Cort Ammon's user avatar
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What is the key difference between SI and MKS units?

The main difference is the standards. MKS is/was based on the traditional standards, e.g. a kg was the mass of one liter of water at a specified temperature, a meter was 1/10,000 the equator-to-pole ...
JEB's user avatar
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3 votes

Does changing units affect Significant Figures

Does changing units affect Significant Figures It should not. There will always be a doubt about the significance of the zeros other than as placeholders with values greater than $10$ like $60\,\rm kg,...
Farcher's user avatar
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Applicability of the $\frac{1}{4\pi}$ pre-factor for Coulomb Attraction in Nanocrystals

Solved thanks to Andrew: The value of "1.8" results from the integration of the 1S eigenstates, which is independent on the choice of unit system. It can hence be concluded that option two ...
Alex Schmitz's user avatar
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Rescaling time in differential equations

It is the non-dimensionalization of the last two differential equations. Assuming $g$ as the acceleration due to gravity ($\text{m}/\text{s}^2$) and $l$ as the length (m), $\sqrt{l/g}$ has the ...
Pustam Raut's user avatar
3 votes
Accepted

Rescaling time in differential equations

It's an usual procedure in deriving non-dimensional equations, from the dimensional ones: angles have no physical dimensions, they wanted a "scaled" (non-dimensional) time as well. You just ...
basics's user avatar
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Relationship between bel and decibel

This is similar to the accepted answer. Suppose we have power $P$ and $P_0$. We express the power $P$ in B (Bel) relative to $P_0$ as \begin{align} L =& \log_{10}(P/P_0)\text{ B}\\ =& \log_{...
Jagerber48's user avatar
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5 votes

What are natural units?

You already live in a world where natural units apply. The speed of light is exactly $1$ light-year/year, or equivalently $1$ light-second/second. Or approximately $1$ foot/nanosecond. This is useful ...
mmesser314's user avatar
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Relationship between bel and decibel

I was asking myself the same question as this guy If a 10th of a bel is a decibel, why are we multiplying by 10, shouldn't we be dividing by 10? Answer, we don't want one 10th, we want the number of ...
Cot Sabaca's user avatar
1 vote

How were angles measured in ancient times?

One degree is defined as $\frac 1 {360}$ of a full revolution. If you are creating a measuring instrument it is probably more convenient to define it as $\frac 1 {90}$ of a right angle or $\frac 1 {60}...
gandalf61's user avatar
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How were angles measured in ancient times?

the 360-degree circle has its origins in Babylonian astronomy combined with the need for a consistent bureaucratic calendar in the Babylonian state. As a bonus, it has factors of 2, 3, and 5, yielding ...
niels nielsen's user avatar
0 votes
Accepted

Convert Coulomb's law in CGS units to SI units

Coulomb's law gives the force between two charges. This force is proportional to each of the two charges, and inversely proportional to the square of the distance between them. So, we will have some ...
Riley Scott Jacob's user avatar
3 votes
Accepted

Why can't we have accelaration in the form of meters per minutes*seconds?

There is nothing inherently wrong with this, it's fine to replace any unit of measurement with any other equivalent unit of measurement. 1 minute is the same thing as 60 seconds, or 1/60th of an hour -...
Nuclear Hoagie's user avatar
1 vote

Why can't we have accelaration in the form of meters per minutes*seconds?

I have seen kilometers per hour per second and miles per hour per second. I haven't come across meters per minute per second before but there's nothing wrong with it. It's just that meters per ...
M. Enns's user avatar
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2 votes
Accepted

The Principle of Homogeneity of dimensions states that you can add,subtract quantities with same dimensions but we cannot add a constant with an angle

Dimensional homogeneity principle should be interpreted like so,- that you can't compare or equate two quantities if they have different dimensions (like distance to speed). If they have same ...
Agnius Vasiliauskas's user avatar
2 votes

What are dimensions and how are they defined?

Dimensions of physical quantities are not related to spacetime dimensions. Dimensions of physical quantities tell us how a given quantity depends on different units of measurement. Dimensions of ...
Níckolas Alves's user avatar
1 vote

Dimensions of constants

Pure numbers are dimensionless, but numbers that measure things usually are not. A length can be $12$ inches or $1$ foot. Units matter here. If you say the length is $12$ or $1$, you don't know how ...
mmesser314's user avatar
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Dimensions of constants

dimension of constant such as speed of light (C)=M0L1T-1. dimension of planks constant=[ML2T-1]. dimension of number such as 1,2,3,4......etc have no dimesion
sumit's user avatar
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3 votes

Dimensions of constants

Take for example the gravitational constant. Expressed in SI units it is: $$G=6.674\cdot 10^{-11}\frac{\text{m}^3}{\text{kg}\cdot\text{s}^2}$$ You can also express this constant in imperial units. You ...
Thomas Fritsch's user avatar

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