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Homework Help: Box with spring coneected

  1. Nov 26, 2007 #1


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    [SOLVED] box with spring coneected

    1. The problem statement, all variables and given/known data

    2 Blocks of mass M and 3M are placed on a horizontal frictionless surface. A light spring is attatched to one of them and the blocks are pushed together with the spring between them. A cord initally holding the blocks together is burned; after that happens, the block of mass 3m moves to the right with a speed of 2.00m/s

    a) What is the velocity of the block of mass M?

    b)find system's original elastic potential E, taking the M= 0.350kg

    c) Is the original energy in the spring or cord?

    d) Is the momentum of the system conserved in the bursting-apart process?
    How can it be with no motion beforehand and plenty of motion afterward?

    http://img208.imageshack.us/img208/6215/boxwithstringsb5.th.jpg [Broken]

    2. Relevant equations

    Ki= Kf

    3. The attempt at a solution

    [tex] SOLVED[/tex] (figured it out)
    Last edited by a moderator: May 3, 2017
  2. jcsd
  3. Nov 27, 2007 #2


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    In this system the total energy is conserved. Therefore PE of the spring is equal to the total KE of M and 3M. Here spring constant or amount of compression is not needed. While calculating cancel M.
  4. Nov 27, 2007 #3


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    Oh..I just figured that out while waiting for a response to my post.

    Thanks :smile:
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