Having a little trouble with this one: A 4kg mass is attached to a spring and executes simple harmonic oscillation with a period of 1.50s. The total mechanical engery of the system is 12J. What is the spring constant. Determine the amplite. I was able to find the amplitude which is 0.585m but am not able to find the spring constant. The formula that I have for spring constant you have to know the angular frequency so I do not think that is right. Can anyone help?