1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Significant Digits Ruler -To what decimal point

  1. Apr 23, 2013 #1
    Significant Digits Ruler -To what decimal point
    To what decimal point do I write the number 30 if the uncertainty is 0.0625?
    The ruler has 1/8 marks.

    Thank you :)
     
  2. jcsd
  3. Apr 23, 2013 #2

    berkeman

    User Avatar

    Staff: Mentor

    Welcome to the PF.

    You are required to show your Attempt at a Solution before we can offer any tutorial help. How would *you* approach this problem?
     
  4. Apr 23, 2013 #3
    I thought it would be 30.000 +- 0.0625 bc there are 3 sig figs in the uncertainty, but I'm not sure. :/
    Also, should the uncertainty be rounded since it looks very precise? I'm so sonfused
     
  5. Apr 23, 2013 #4

    haruspex

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member
    2016 Award

    There are three sources of error here. One is that you are rounding to the nearest mark. That introduces an uncertainty of exactly ±0.0625. Next is any error in the placing of the marks on the ruler. You could handle that by rounding the first uncertainty up a little, ±0.064, say. Third is any error in your decision of which is the nearest mark. That's the same in nature as the second error, but statistically independent.
    Now, suppose you decide the error is ±0.07 and you measured the value as 30.375. It would be quite appropriate to write the answer as, say, 30.375±0.070, strange though that may seem. But it would also be reasonable to compromise there, e.g. with 30.37±0.08.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted



Similar Discussions: Significant Digits Ruler -To what decimal point
  1. Significant digits (Replies: 2)

  2. Significant Digits (Replies: 3)

  3. Significant Digits (Replies: 2)

  4. Significant digits (Replies: 1)

  5. Significant digits (Replies: 1)

Loading...