Calculate spring constant for cart attached to a spring

[SharpCode]

Homework Statement

A Cart is floating on an airtrack and is connected by a spring to one fixed object. The cart executes a simple harmonic motion with a period of 4 seconds. Its mass is 2kg. Its maximum displacement from rest position is 1.8m. Calculate the spring constant and provide units.

Homework Equations

F= -kx

The Attempt at a Solution

The units would be N/m i am guessing but i am still a little lost. k is the spring constant rearranged it should be:
k = F/x right?

COULD A MOD PLEASE REMOVE THIS OR MY OTHER THREAD. INTERNET CUT OUT BUT MUST HAVE SUBMITTED TWICE

 

[pcm]

how do you relate k , period and mass?

 

[SharpCode]

Hey pcm i posted in my other thread

hoping this one gets removed... double posted by accident