A massless spring of length .310 m is compressed to 71.0 % of it's relaxed length, and a mass M=.150 kg is placed on top and released from rest. The mass then travels vertically and it takes 1.10 s for the mass to reach the top of its trajectory. Calculate the spring constant, in N/m. Use g= 9.81 m/s^2. Assume that the time required for the spring to reach its full extension is negligible.(adsbygoogle = window.adsbygoogle || []).push({});

I really have no idea how to do this problem. I tried using conservation of energy and solving for k, I'm not sure if I even have all of the forms of energy

(1/2)kx^2= (1/2)mv^2

(1/2)k(.2201)^2= (1/2)(.150)(10.78^2)

to get 360.0 N/m , which wasn't right

Any help would be appreciated. Thanks

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# Homework Help: Spring constant

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