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Spring help

  1. Nov 23, 2003 #1
    A block having a mass of 2.80 kg is given an initial velocity of 1.2m/s when it collides with a spring. The constant force of friction acts between the block and the surface with (mu sub k=0.5) and the force constant of the spring is k=100N/m. What is the maximum compression?

    I've been stuck on the problem for a while.
    Workfriction + KEi + PEi = KE + PE

    KEi =2.02J
    fk =13.72
    KE=0
    PEi =0

    therefore (13.72 N + 2.02 J)/ 50N/m = x^2

    Is this equation right? If so, how do I find x?
    I tried to work it but I can't figure out how to add newtons and joules divided by N/m and end up with x in meters...

    Please help
     
    Last edited: Nov 23, 2003
  2. jcsd
  3. Nov 23, 2003 #2
    1N=1kgm/s2 ---- remember F=ma?
    1J=1kgm2/s2 ----- remember W=Fx?
     
  4. Nov 23, 2003 #3
    I still need more information....I'm not as smart as some as you. Someone get me started and I can figure it out...
    Thanks
     
  5. Nov 24, 2003 #4

    NateTG

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    Science Advisor
    Homework Helper

    There should be massive alarms going off when you get N+J in a physics problems.

    If you put your equation together right, this should be easy:

    KEi=Workfriction+PEspring
    or
    1/2mv02=ffrictionx+1/2kx2

    Just remember the quadratic formula.
     
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