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Homework Help: Two objects with springs collide

  1. Nov 2, 2012 #1
    1. The problem statement, all variables and given/known data
    Two air blocks with masses 224 g and
    130 g are equipped with identical springs
    (k = 2490 N/m). The blocks move toward
    each other with identical speeds of 1 m/s on a
    horizontal air track and collide, compressing
    the springs.
    Find the maximum compression of the
    spring attached to the 224 g mass.

    2. Relevant equations

    3. The attempt at a solution
    okay so the thing that I don't understand is do the springs split the kinetic energy from the objects equally and if they do I still do not understand what I'm doing wrong.
  2. jcsd
  3. Nov 2, 2012 #2


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    Staff: Mentor

    Hi sarmstrong, welcome to Physics Forums.

    It's hard to say what you're doing wrong if we can see what it is you're doing... can you show an attempt in detail?

    Two identical springs in series behave overall as if they were a single spring with the same spring constant; the compression will be shared, so half can be attributed to each.

    Have you considered looking at the problem from the center-of-momentum frame of reference? In that frame the center of collision remains fixed in place, so both masses come to rest at the same instant with both springs as fully compressed as they're going to get. Kinetic and potential energy are conserved ...
  4. Nov 2, 2012 #3

    Simon Bridge

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    Science Advisor
    Homework Helper

    What would happen if you had two blocks (as above) without springs, but there is a spring attached to the track that they both hit at the same time?

    See - during the collision, you have two blocks with a single spring between them.
    (careful - the blocks do not have equal and opposite momenta)
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