Amplitude and period of a spring

[musicmar]

Homework Statement

A 340 g mass is attached to a vertical spring and lowered slowly until it rests at a new equilibrium position, which is 30 cm below the spring's original equilibrium. The spring is then set into simple harmonic motion. What is the period of the motion?

Homework Equations

I don't know how to enter greek letters, so let w=omega
x(t)=Acos(wt)
w=sqrt(k/m)
w=2pi*f

The Attempt at a Solution

I tried it using conservation of energy, but that didn't really help because v has many extra variables in its equation. Does the addition of the mass cause a 30 cm increase in the amplitude, or is it only half? I just thought of something. If I knew how to relate the angular frequencies, I could use conservation of energy, but I don't know how to relate the angular frequencies.

 

[ehild]

Do you know how the spring constant is defined?

ehild