Questions tagged [units]
Units are standards of measurement used for different types of quantities.
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Can a physical quantity be arbitrarily introduced? [duplicate]
Acceleration involves a squared time item, and Newton's law of universal gravitation contains a product of two masses. Such mathematical expressions seem to be meaningless when taken in isolation; ...
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Why Can't We Simplify the Ideal Gas Law to $pV = nT$?
As someone with a small background in physics, I find myself questioning the necessity of the ideal gas constant $R$ in the Ideal Gas Law $pV = nRT.$ Why can’t we simplify this relationship to $pV =nT$...
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Non-spin factor of 2 when working with density of states
I'm trying to follow the math in an old paper discussing the electrical characteristics of niobium. The paper skips over a fairly simple substitution/unit conversion:
Here, $\rho_i$ is the intrinsic ...
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Is it meaningful to talk about percentage increase for temperatures measured in Celsius or Fahrenheit?
It seems like it's meaningful to talk about percentage increases in measurements like length, duration and area: A statement like "This stick is 57% longer than that stick" is consistently ...
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What kind of mathematical objects are units of measurement?
Multiplication and division of units of measurement seems to be defined, e.g., $\mathrm{N}\times\mathrm{m}=\mathrm{N}\text{-}\mathrm{m}$, m/s = m/s (a rather unsatisfactory example---help).
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What does it mean if an aircraft has a radar cross-section of 20 dB?
In the Aviation Week issue of 15 February 1999, David A. Fulghum wrote the following in the article “JSF Reflection Is Golf Ball-Sized” on page 27:
The overall goal of the JSF program is to produce ...
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What is the tension for a cosmic string formed at the electroweak scale?
Cosmic strings are characterized by their dimensionless tension, $G\mu$. Their mass per unit length $\mu$ is given by the square of the energy scale of their formation. For strings formed at the ...
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Why is grid-wide battery storage capacity measured in units of power instead of energy?
A battery stores energy, not power. It would not make any sense for something to "store power", because power is not a conserved quantity.
Therefore, the energy storage capacity of an ...
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What does it mean to multiply units in physics?
Note: I am a beginner and currently have no formal education in physics
I've never fully grasped what multiplying units of measures really means. You could say I should be just as confused by things ...
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How much value is there in relating quantities with same dimensions/units? [duplicate]
The best way I can describe what I mean in the title is with examples. When you look at the Bernoulli equation, specifically whn written as $\frac12 \rho v^2 + \rho gh + p = \rm{constant}$, or our ...
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CGS unit of charge in dimensional analysis
For converting a $\text{Newton}$ into a $\text{Dyne}$, we can simply use $nu = \text{constant}$ where $n$ is the magnitude and $u$ is the unit.
A similiar method can be used to convert all SI units ...
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Physical implications of the inexact value of circumference of a circle
Since $\pi$ is an irrational non-terminating non-repeating fraction therefore if it is multiplied by any real number that cannot be represented as a product of $\pi$, the result will be a non-...
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Does $\frac{1}{4\pi G}$ have an intuitive physical meaning? [closed]
The gravitational field $\vec{g}$ generated by an object whose density is given by $\rho(\vec{r})$ is given by $\vec{g}=-G∭_{object}\frac{\rho dV}{r^2}\hat{r}$.
If we define a gravitational potential $...
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Is it correct to mention the unit of speed with the corresponding velocity vector? [duplicate]
If a particle moves at speed of 5m/sec along direction $\frac{1}{5}(3\hat{i} + 4\hat{j})$ then is it correct to say that velocity is $(3\hat{i}+4\hat{j})$ m/sec ?
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Units of angular velocity and frequency
I was recently studying for an exam and had a small argument with my teacher when I said that the angular velocity of something was in hertz.
The way I see it: $dim(ω)=\frac{rad}{s}$ but radians are ...
