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[url=http://www.phy.ntnu.edu.tw/ntnujava/index.php?topic=215.0]Coupled springs[/url],
[url=http://www.phy.ntnu.edu.tw/ntnujava/index.php?topic=432.0]Two blocks and two springs connected to a wall on a frictionless surface[/url] ,
[url=http://www.phy.ntnu.edu.tw/ntnujava/index.php?topic=425.0]A rod supported by two spring on both ends[/url]