*sigh* I'm SURE there is a perfectly reasonable solution to this problem, unfortunately for me it remains just beyond the next horizon. 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.