[4] Problem: No. 16, Rotating spring, IYPT 2010 Author: Reza Montazeri Namin Document: http://archive.iypt.org/iypt_book/2010_16_Rotating_spring_Iran_RMN_v1.pdf Date of Review: 04/12/2011 The author put much effort to enhance the article. I have only two comments to conclude the work: 1.) Two figures are mislabeled. Relabel Fig. 2 -> Fig. 4, and Fig. 3 -> Fig. 6. 2.) Increase font size in figures 3, 5 and a little in figure 6. Reviewer Recommendation: With mentioned minor improvements done, I recommend the article for publishing.