How Do You Calculate Mass and Acceleration in a Spring Mass System?

[Ahmad786]

Homework Statement

An object suspended from a spring with a spring constant of 2.56 N/m vibrates with a frequency of 0.148 Hz
a. What is the mass of the object
b. What is the acceleration of the object at a displacement of -0.120m from the equilibriam position

Homework Equations

a. T=2pi\sqrt{}m/k m=Tk/4pi²' T=1/f
b. a=-kx/m ?

The Attempt at a Solution

a.T=1/f T=1/0.148Hz T=6.756756757s m=Tk/4pi²' m=(6.756756757s)(2.56N/m)/4pi²' m=2.96kg ---- I do not understand if this is right and I think I made a mistake ----
b. I can't figure out what equation to use and how to manipulate it to get an equation for acceleration for the condition

 

[ideasrule]

a. It's right.
b. It's a=-kx/m.