Solving SHM Spring Mass Homework Problem

[laxbrah44]

Homework Statement

A spring of unstretched length L0 = 60.5 cm and spring constant K is suspended vertically as shown. A mass m is attached to the spring and it stretches the spring to a length of 123 cm. Then the mass is pulled down an additional 8.74 cm from the equilibrium position and released. At its maximum deformation, the spring force is 88.7 N.

A. What is the period of the oscillation?
B. What is the mass m?
C. What is the spring constant K?
D. What is the energy in the oscillation?

Homework Equations

kx=mg T=2pi(m/k)^.5 E= 1/2kA²

The Attempt at a Solution

I found the period as 1.58s by doing (stretched - unstretched) / 9.8 and then sq root that then multiply by 2pi. However, I am completely lost on how to find mass. Using substitution, etc always gets me a negative number. Once I know how to get mass it'll be easy to find K and Energy. Thanks

 

[vela]

You want to find k first. Use the info you were given in the last sentence.