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!

Homework Help: Uncertainty/error question

  1. Oct 1, 2008 #1
    1. The problem statement, all variables and given/known data

    If the relative error of m is 1% and of h is .5%, what is the error of log(mh)?

    2. Relevant equations

    d/dx(lnx)=1/x, [tex]\delta[/tex]lnx=[tex]\delta[/tex]x/x

    3. The attempt at a solution
    [tex]\delta[/tex](ln0.43(mh))=[tex]\delta[/tex](0.43lnm + 0.43lnh)
    =[tex]\delta[/tex](0.43ln0.01 + 0.43ln0.005)

    i'm pretty sure this isn't right since it's a negative number, i have no idea how to do this
  2. jcsd
  3. Oct 2, 2008 #2


    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper

    I don't see how the 0.43 is coming into this.

    First, what's the relative error in m*h?

    Second, if you want the error in ln(x), replace x with x0(1±ε). (ε is the relative error in x).

    See if you can work it from there.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook