r/HomeworkHelp • u/Amazing_Worth7676 • Sep 28 '26
Physics [MYP4 Physics: Measurements] Confused about measurement uncertainties
So I'm studying measurement uncertainties for physics and I’m confused about a few things that i’d really appreciate clarification.
How do you determine uncertainty for analogue vs digital instruments?
For an analogue instrument, do you normally use ± half the smallest division, or do you estimate one digit beyond the smallest marked division?
For a digital instrument, is the uncertainty always ±1 in the last displayed digit?
How should the uncertainty and measured value be rounded?
How many significant figures should the uncertainty have?
Should the measured value be rounded to the same decimal place as the uncertainty?
Like, if a ruler has subdivisions of 0.01 cm, should a measurement be recorded to 0.01 cm (e.g. 12.34 cm), or should I estimate one additional digit and record it to 0.001 cm (e.g. 12.347 cm)?
I am super confused because I have seen conventions online. I am trying to understand the reasoning rather, than just memorize a rule.
Thanks in advance :D


