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Homework Help: Kinectic energy of spring

  1. Jul 26, 2008 #1
    1. The problem statement, all variables and given/known data
    A spring of mass m is pulled away from the centre from its two ends with a velocity v at a particular instant.Find its kinetic energy.

    2. Relevant equations
    KE=.5kx2 is useless since k is not given but m is given
    So i think i will have have to use .5mv2

    3. The attempt at a solution
    the velocity of the spring will gradually decrease and will become 0 at the centre.
    if v(x) is the velocity at a particular distance from the centre then we can write
    kinetic energy=1/2 m/l*dx*v(x)2(dx being a small distance x)
    and then integrate to find KE.
    i am unable to find v(x) as a function of x.
  2. jcsd
  3. Jul 26, 2008 #2


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    Science Advisor
    Homework Helper

    Welcome to PF!

    Hi atri.shivam! Welcome to PF! :smile:

    v(x), at any particular time, will be proportional to x … that's how springs work! :smile:

    (assuming there's no wave in the spring! :rolleyes:)
  4. Jul 27, 2008 #3
    but what will be the equation of v(x)
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