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Homework Help: Spring Constant (NEED HELP !)

  1. Mar 3, 2009 #1
    1. Problem

    A spring with a pointer attached is hanging next to a scale marked in millimeters. Three different packages are hung from the spring, in turn, as shown below.

    07_39.gif

    (a) Which mark on the scale will the pointer indicate when no package is hung from the spring?
    (a) ? mm

    (b) What is the weight W of the third package?
    (b) ? N

    2. Attempt at a solution

    240 N - 110 N = 130 N
    60 mm - 40 mm = 20 mm

    130 N = -k * 20 mm <-- Is this formula correct? If not, how do I find the answers to (a) and (b)?
    k = -6.5
     

    Attached Files:

    Last edited: Mar 3, 2009
  2. jcsd
  3. Mar 3, 2009 #2
    Never mind. I found the answers.

    (a) 23 mm
    (b) 45 N

    Thanks for nothing. lol.
     
    Last edited: Mar 3, 2009
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