Units are standards of measurement used for different types of quantities.

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Addition of different physical quantities

We all know the "apples and oranges" rule which says that it's meaningless to add or subtract two different quantities like apples and oranges. But the same rule doesn't hold for the multiplication ...
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4answers
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What exactly is a mole?

I have some trouble understanding exactly what a mole represents. As I understand, one unit mole is 1/12 of the mass of an atom of carbon-12 (thus it is the mass of one nucleon?). What is a mole, ...
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5answers
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Whats the range of dimension exponents in the SI Units system?

I am working on a software library for Units of Measure. To represent dimensions, I need to know the required range of exponents for each of the seven base units (precisely, I need to know the ...
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2answers
737 views

Fundamental units

Is it right that all units in physics can be defined in terms of only mass, length and time? Why is it so? Is there some principle that explains it or is it just observational fact?
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4answers
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Simple Harmonic Motion - What are the units for $\omega_0$ ?

I'm trying to understand the units in: $mx''+kx=0$ And the general solution is $x(t)=A \cos(\omega_0 t)+B \sin(\omega_0 t)$ Let $\omega_0 =\sqrt{\frac{k}{m}}$ - the unit for the spring constant $k$ ...
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1answer
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Non-Dimentionalization of equations

I am trying to understand a paper in which they mention; " We non-dimentionalize the problem hereafter by selecting mass, length and time units such that the fluid density $\rho\equiv1$ the ...
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3answers
324 views

Help getting the distance an object has moved

What is a distance an object went through at the speed of 14hm/min for 6 hours? I am having problems with conversions. First, I tried passing 14hm/min to m/s. I did it alright. But now I am unsure. ...
10
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3answers
722 views

How can I understand counterintuitive units like $\text{s}^2$?

One of the things I never understood, but was too afraid to ask is this: how should I think of things like $\frac{\text{kg}}{\text{s}^2}$. What exactly is a square second? Square foot makes sense to ...
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4answers
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Fundamental question about dimensional analysis

Let me admit beforehand that this is quite possibly a very stupid question. I was also uncertain of where to post this question, as it doesn't fit cleanly into either physics or math stackexchange. ...
3
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2answers
874 views

Why do the formulas for planck's units use h instead of hbar?

On the Answers.com page on Planck length, I see two almost-same formulas for the Planck length that differ only by the use of h and hbar. However, the constants are the same, and my calculator gives ...