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Homework Help: Mass of a String

  1. Jan 19, 2010 #1
    1. The problem statement, all variables and given/known data
    A 1.50-m-long string is under 30.0 N of tension. A pulse travels the length of the string in 50.0 ms.

    2. Relevant equations

    v of string = sq rt of (Tension of string/ string's mass-to-length ratio)

    string's mass to length ratio= m/L


    3. The attempt at a solution

    So, the pulse takes 50.0 ms to travel through 1.5 m of string. So, the velocity of the pulse is 1.5 m/.050 s.

    V= 1.5/.050 = 30 m/s

    Now that I know the velocity, I can use the V of string equation.

    V[tex]^{2}[/tex]= T/[tex]\mu[/tex]
    [tex]\mu[/tex]= T/V[tex]^{2}[/tex]
    [tex]\mu[/tex]= 30.0N/ (30m/s)[tex]^{2}[/tex]
    [tex]\mu[/tex]=.033

    [tex]\mu[/tex]=m/L
    [tex]\mu[/tex]*L=m
    .033*1.5=m
    m=.049995 or .05 g

    However, master physics disagrees with this answer. What am I doing incorrectly?
     
    Last edited: Jan 19, 2010
  2. jcsd
  3. Jan 19, 2010 #2

    kuruman

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    The answer should be in kilograms not grams.
     
  4. Jan 19, 2010 #3
    Actually, the unit they want mass in is g. Sorry. Forgot to put that in there.
     
  5. Jan 19, 2010 #4

    kuruman

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    I was not clear explaining what I meant. The answer that you got, 0.05 is in kilograms. You need to convert that to grams. Did you enter 0.05?
     
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