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Homework Help: Simplifying math homework help

  1. Dec 27, 2009 #1
    1. The problem statement, all variables and given/known data
    Show how to simplify (mBvB2 - mBvC2 - mCvC2)/(mBvB2) to mC/(mC + mB)


    2. Relevant equations
    vB is not equal to vC.
    vB = muzzle speed of a bullet = unknown value
    vC = speed of the clay block after it is hit by the bullet = unknown value
    vB = ((2gh)0.5(mB + mC))/mB
    vC = (2gh)0.5
    g = gravitational acceleration
    h = unkown height
    mB is not equal to mC
    mB is the mass of a bullet. mB is unkown though
    mC is the mass of a clay block. mC is also unkown

    3. The attempt at a solution
    I have tried many different methods, but I still cannot show how to simplify the above equation
    Please Help!
     
    Last edited: Dec 27, 2009
  2. jcsd
  3. Dec 27, 2009 #2

    sylas

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    Science Advisor

    Re: Simplifying

    You need more equations showing some relationships between your variables. If the variables are uninterpreted, the equation doesn't hold. For example, suppose vB = vC. In this case the equation on the left reduces to -mC/mB, which is only matches the right hand side when mC = 0 or mC = -2mB.

    So you need more information.

    Cheers -- sylas
     
  4. Dec 27, 2009 #3
    Re: Simplifying

    I just edited the thread. Hope all the info are there
     
  5. Dec 27, 2009 #4

    sylas

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    Science Advisor

    Re: Simplifying

    Yes. Can you cancel out the variables you don't need? That is, g and h?
     
  6. Dec 27, 2009 #5
    Re: Simplifying

    Yeah of course
     
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