What Distance x Gives the Least Period for a Physical Pendulum?

[ghetto_bird25]

Homework Statement

In Fig. 16-41, a stick of length L = 1.6 m oscillates as a physical pendulum. (a) What value of distance x between the stick's center of mass and its pivot point O gives the least period? (b) What is that least period?
http://edugen.wiley.com/edugen/courses/crs1141/art/qb/qu/c16/Fig15_46.gif

Homework Equations

well I'm assuming you have to use the equation for a a physical pendulum which is
T= 2pi \sqrt{I/mgh}
where I is the rotational inertia, m is the mass, g is gravity, and h is the distance between the axis of rotation and the centre of the pendulum.

The Attempt at a Solution

i tried using that equation but i don't understand the value for I because I am assuming if the value for h changes then the other end of the rod changes as well.

 

[azatkgz]

Moment of Inertia of the center of mass is

I_0=\frac{mL^2}{12}

If it is pivoted distance x from the centre

I=I_0+mx^2

T=2\pi\sqrt{\frac{I}{mgx}}=2\pi\sqrt{\frac{I_0+mx^2}{mgx}}

for T minimum we have
\frac{dT}{dx}=0