Calculating Length of Pendulum with 12.0 N Weight and 1.2 s Swing

[Jtappan]

Homework Statement

A clock has a pendulum that performs one full swing every 1.2 s (back and forth). The object at the end of the pendulum weighs 12.0 N. What is the length of the pendulum?
____ m

Homework Equations

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The Attempt at a Solution

What is the equation i would use here?

 

[amolv06]

http://www.google.com/search?source=ig&hl=en&rlz=&q=period+of+a+pendulum&btnG=Google+Search