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Determining spring constant

  1. May 4, 2009 #1
    1. The problem statement, all variables and given/known data

    determine the spring constant state results in SI units.

    here is the chart. this isn't making sense to me.

    Scale Reading vs x coordinate
    1.05 N--55 cm
    .75 N---45 cm
    .90 N--50 cm
    1.35 N--65 cm
    1.20 N--60 cm
    .6 N--40 cm

    thats all the info i have. i'm just not getting a solid answer


    2. Relevant equations

    k=-F/x

    3. The attempt at a solution

    i've attempted many different times, each time coming up with a different spring constant ranging from -3.86 to 3.
     
  2. jcsd
  3. May 4, 2009 #2
    To determine the spring constant, you need to find out by how much increases the force exerted by the spring, if you stretch it by a certain length. By the formula, we see that the force increases linearly, so only two measurements are enough to find out the spring constant.
     
  4. May 4, 2009 #3
    ya i'm not really sure what your trying to say there....can you clarify what you mean by "you need to find out by how much increases the force exerted"?

    i assure you this is all the info i have
     
  5. May 4, 2009 #4
    It really is enough info. Do you know what F, k and x are in the equation you've mentioned?
     
  6. May 4, 2009 #5
    you need to find out by how much increases the force exerted means that if you stretch the spring (pull it, increase it's length) then it's trying to reset the original length, therefore pulling its ends with a certain force.
     
  7. May 4, 2009 #6
    What the formula means is;

    The Force applied to something = Spring constant * The change in length (when that force is applied)

    You have the force applied, you have the change in length, just bash it into your calculator, if your still struggling show us your working
     
  8. May 4, 2009 #7
    Why are you so sure you don't have the right answer already? What methods are you using to determine different answers?
     
  9. May 4, 2009 #8
    so is it just 3 N/m?

    or do i not take the change in force?

    (1.05 N-.9 N)/(.55-.50 m)

    edit:i don't think i'm doing right because i'm getting different answers on this website everytime
    http://www.calculatoredge.com/new/hookelaw.htm
     
  10. May 4, 2009 #9
    Looks correct to me.
     
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