Questions tagged [metrology]

The study of measurements

211 questions
113 views

How to properly read a measurement result if it is a number?

If the result of a measurement is i.e. $3.2 \pm 0.7$, what is 0.7? At which confidence level we know that the real result is inside of this interval?
337 views

Are circularly defined {velocity, distance, and time} a problem in physics?

In order to measure velocity, one needs a calibrated measuring stick and clock. But in order to calibrate a measuring stick you need a calibrated clock and velocity. And in order to calibrate a clock ...
960 views

Could I get an explanation of Avogadro's number and how it relates to determining the mass of a substance? My chemistry textbook only serves to confuse me and the Wikipedia article is aimed towards a ...
229 views

What widely recognized organizations set standards used by physics?

I recently answered a question about the meaning of the word "dimension" as used in physics. In that response, I provided the definition given in the International Vocabulary of Metrology (VIM) and ...
1k views

Meaning of dimension in dimensional analysis

I was wondering what dimension can mean in physics? I know it can mean the dimension of the space and time. But there is dimensional analysis. How is this dimension related to and different from the ...
2k views

Is anything actually 1 meter long (or 1kg of weight)?

I believe that no real objects are actually (exactly) 1 meter long, since for something to be 1.00000000... meters long, we would have to have the ability to measure with infinite precision. Obviously,...
27k views

Refractive index of air in dependence of temperature

What is the exact dependence of the refractive index of air and the temperature? Is there a theoretical derivation of it?
743 views

If time standard clocks and any memories about the time standard are destroyed, can we recover the time standard again?

Assume the time standard clocks and any memories about the time standard are destroyed. Can we recover the time standard again exactly? Recovering the time standard again means we can determine the ...
5k views

Measuring the speed of light and defining the metre - absolute or relative?

If the metre is now defined as the distance light travels in vacuum in $1/299\,792\,458^{\textrm{th}}$ of a second and the speed of light is accepted to be $299\,792\,458\ \textrm{m}\,{\rm s}^{-1}$, ...