Your friend is trying to construct a clock for a craft show and asks you for some advice. She has decided to construct the clock with a pendulum. The pendulum will be a very thin, very light wooden bar with a thin, but heavy, brass ring fastened to one end. The length of the rod is 80 cm and the diameter of the ring is 10 cm. She is planning to drill a hole in the bar to place the axis of rotation 15 cm from one end. She wants you to tell her the period of this pendulum.

The period of the pendulum is  

Explanation:

The diagram illustrating this setup is shown on the first uploaded image

From the question we are told that

     The length of the rod is

       The diameter of the ring is

       The distance of the hole from the one end  

From the diagram we see that point A is the center of the brass ring

 So the length from the axis of  rotation is mathematically evaluated as

Now the period of the pendulum is mathematically represented as

0 = 0.40 / 0 = 0

= 0.20 = 9.80 ⁄2 =?

=0 , = = 0.20 =0.50 0 0.40 ⁄

=0−122 =0−12(9.80 ⁄2)(0.50)2 =1.2