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Homework Help: I'm struggling on manipulating kinematics

  1. Feb 4, 2016 #1
    1. The problem statement, all variables and given/known data
    Given the equations X=X0+v0t+1/2at^2 and v=v0t+at, show that an expression for v that has no explicit dependence on time can be written as v=+-√v0^2+2a(X-X0)

    2. Relevant equations

    3. The attempt at a solution
    I thought I would manipulate the first given equation to be X-X0/t = [1/2(v-v0)] but as I got to the end it didn't work. Please help.
  2. jcsd
  3. Feb 4, 2016 #2


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    Staff: Mentor

    Welcome to the PF.

    Please show us in detail your work. We can try to help if you show your work to us. :smile:
  4. Feb 4, 2016 #3


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    Homework Helper
    Gold Member

    Shouldn't this be v=v0+at?
    I believe taking square on both the sides of this equation would help.
  5. Feb 4, 2016 #4
    I took X=X0+v0t+1/2at^2 and separated v0t because v=v0+at so it can just say vt . I then subtracted X0 from both sides and divided by t on both sides. My final equation was X-X0/t=[1/2(v+v0)]
  6. Feb 4, 2016 #5
    Yes, sorry I made a typo
  7. Feb 4, 2016 #6
    I manipulated the wrong equation
  8. Feb 5, 2016 #7
    the standard notation is v=u+at and s=ut+1/2*a*t2. Express t=(v-u)/a, substitute in s eqn, simplify and you get the answer. v2-u2=2as.
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