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Homework Help: Mass between 2 Springs k1,k2

  1. Jan 29, 2010 #1
    1. The problem statement, all variables and given/known data
    Hey

    The part of the question that i am not all the sure about is Newtons second law.
    and the Omega
    the Situation is as followed

    ]/\/\/k1\/\/\[m]/\/\/k2/\/\[

    There are 2 springs k1,k2 and a mass in between.


    2. Relevant equations

    F=ma and F=-kx

    x=Asin(omega(t)+theta)
    3. The attempt at a solution

    Now i find it a little confusing because there are 2 springs with both different constants.

    I think the solution is

    ma=(-k1+k2)x which turns in to ma=(k2-k1)x so a+((k2-k1)x)/m=0
    now when finding the solution for Omega i get

    omega= -sqr(((k2-k1)x)/m) now the (-) sign is annoying me, usually its not there,
    so i think i might made a mistake with the (k2-k1),

    thanks for the help
    1. The problem statement, all variables and given/known data



    2. Relevant equations



    3. The attempt at a solution
     
  2. jcsd
  3. Jan 29, 2010 #2
    There is a property for the system you are trying to figure out that I cant quite recall, but subtracting the constants is not right. Think about the physics of the situation.

    ]/\/\/\/\/\/\/\/\/k1\/\/\[m]/\/\/k2/\/\/\/\/\/\/\/\/[ this then goes to this
    ]\/\/k1\/\/\[m]\/\/\/\/\/\/\/\/k2\/\/\/\/\/\/\/\/\/\/[
    so you know that this point k1 is compressed to it is pushing m to the right.
    you also know that k2 is stretched, so it will pull m also to the right. So you know that these two forces must add, my guess would be that it is by a factor of 1/root(2). You can find this easily online, let me know what the answer ends up being
     
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