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Homework Help: Mechanical engergy, energy conservation

  1. Apr 20, 2013 #1
    1. The problem statement, all variables and given/known data
    A 10-kg block is released from point A. The track is frictionless except from the portion between B and C which has a length of 3.0 meters. The block travels down the track, passes through BC and first collides with a small block (m=2kg), then they travel together and later hit the spring.

    Q: Find the velocity of the block after it passes BC

    There were two questions before it, find the velocity of the block when it reaches point B at the bottom of the track and it's 8.85m/s then I found the work between B and C which is -88.2 J. I tried setting up different equations to find the velocity after it passes B and C, but I am missing something.

    2. Relevant equations
    1/2mv^2, mgh, 1/2kx^2, mgx

    3. The attempt at a solution
    I tried setting the equation equal to the work, -88.2=1/2V^2(m+m), I recently tried -2μkgd=mv2^2-(mv1^2+2mgh1). I am not sure if I am supposed to have the second block in there or not.
    1. The problem statement, all variables and given/known data

    2. Relevant equations

    3. The attempt at a solution

    Attached Files:

  2. jcsd
  3. Apr 20, 2013 #2


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    2017 Award

    Staff: Mentor

    For the velocity at point C, the second block does not matter - it is not a part of the motion yet.
    You probably have the energy of the first block at point B as intermediate result. If it loses 88.2J, what is its energy at point C? This allows to calculate the velocity.
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