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Homework Help: Maybe a dumb question on standard error in equations

  1. Oct 24, 2012 #1
    1. The problem statement, all variables and given/known data

    I am using a value of change in y say 12.10 cm + or - .06cm.

    I am trying to find velocity using the formula
    v= sqrt(2*g*change in y)

    how do I evaluate this equation with my standard error? because I can't just add or subtract the .06cm after since I will have a value for velocity now.

    2. Relevant equations

    3. The attempt at a solution
  2. jcsd
  3. Oct 24, 2012 #2
    Can you just plug in 12.10 cm to get v and then plug in 12.10 cm + .06cm and 12.10 cm - .06cm to figure out the error in v?
  4. Oct 24, 2012 #3
    i'm not sure if this was correct but, I plugged in the value with + then plugged in te value with -. Average the two values, and did + or - the difference between the two
  5. Oct 24, 2012 #4


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    Gold Member

    That'll work. The algebraic way is to approximate sqrt(x + dx) = sqrt(x)sqrt(1+dx/x) as sqrt(x)(1+dx/2x) for small dx.
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