How to write uncertainities on different measurement

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Discussion Overview

The discussion revolves around how to properly express uncertainties in measurements, particularly in the context of using rulers and protractors. Participants seek clarification on notation and the principles behind determining uncertainty values.

Discussion Character

  • Technical explanation, Conceptual clarification, Homework-related

Main Points Raised

  • One participant requests urgent advice on writing uncertainties for measurements.
  • Another participant suggests using the notation x = (3.01 ± 0.01) cm as an example of how to express uncertainty.
  • A later reply emphasizes the importance of rounding uncertainties to one significant digit and aligning the measurement result accordingly.
  • One participant specifies their context involves measurements from a ruler and a protractor, estimating uncertainties as ±1 degree and ±0.5 mm.
  • Another participant explains that the uncertainty for analogue equipment is typically half of the smallest measurement, while for digital devices, it is the smallest measurement itself.

Areas of Agreement / Disagreement

Participants generally agree on the notation and principles of expressing uncertainties, but there are variations in how uncertainties are determined based on the type of measuring device used.

Contextual Notes

There are assumptions regarding the definitions of measurement precision and the types of measuring devices discussed, which may affect the interpretation of uncertainties.

Awsom Guy
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I need some advice on how to write uncertainities on different measurements.
I need this urgently.
Thanks:cool:
 
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with a delta [tex]x \pm \Delta x[/tex]
 


i mean on measurements
 


[tex]x = (3.01 \pm 0.01) \text{ cm}[/tex]

You mean like that? Otherwise, your question is so vague and general, I have no idea what you want.
 


Nick89 said:
[tex]x = (3.01 \pm 0.01) \text{ cm}[/tex]

You mean like that? Otherwise, your question is so vague and general, I have no idea what you want.


That is it exactly what I want.
 


Well, what is your question about it?

You simply write down the result of your measurement, and then you decide what the uncertainty is. You round the uncertainty to one significant digit (0.0193 becomes 0.02) and you round the measurement result to the same amount of digits (as long as they are in the same units). You then write it down as
[tex]y = (x \pm \Delta x) \text{ [unit]}[/tex]
where x is the measurement result and delta x the uncertainty.
 


Well my question was about the measurements in a ruler in mm and a protractor.
I guess it would be +/-1 degree and +/- 0.5mm.
Thanks for your help anyway.
 


Hi there,

I believe I can help you with this one. The uncertainty of an analogue equipment is half the smallest measurement possible (0.5mm for your ruler). The uncertainty of a digital device is the smallest measurement possible (1mm for digital ruler that measures in mm).

Cheers
 

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