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Homework Help: Springs I've been working on this for several hours

  1. Oct 27, 2005 #1
    *sigh* I'm SURE there is a perfectly reasonable solution to this problem, unfortunately for me it remains just beyond the next horizon. :cry:

    The green block (2 kg) is falling at a speed of 29. m/s and is 3.0 meters above the spring. The spring constant is 4.00E3 N/m. What is the maximum hsight that the block will rise after it hits and leaves the spring (use g=9.81 m/s^2)?

    I have
    1) found v when it hits the spring by v^2 = Vnot^2 + 2a(change in)x
    2) found distance compressed by (final rearrangement) d = v(sq rt of)m/k
    3) found v on the way up by (final rearrangement)
    v = (sq rt of) kd^2/2 - mgd
    4) found displacement on the way up by (final rearrangement)
    (change in)x = v^2 - vnot^2 / 2a

    and I come VERY close to the right answer, but not quite there. What am I doing wrong and how can I fix it, please?

    Also, how does the change in gravitational potential energy apply in this situation and what exactly is it?

    Thanks so much.
  2. jcsd
  3. Oct 27, 2005 #2


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    Gold Member

    Well if you came very close to the answer, it might be a rounding issue.
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