Grigoriy S. answered 12/11/21
AP Physics / Math Expert Teacher With 40 Years of Proven Success
As far as I understand, you took the formula for the period of the pendulum and want to put it in a way so, that you could find g and use linear graph for this.
You already wrote that
L / T2 = 4π2g
From here
g = 1 / 4π2 (L / T2)
At first you plot the graph L vs T2 . You put T2 on horizontal axis and L - on vertical. Then you need to find the slope of this graph (tan of the angle between the graph and horizontal axis).
Now you can write
g = 1 / 4π2 x Slope
Hence, if now you divide the slope of the graph by 4π2 , you will get the experimental value of the acceleration due to gravity g. And you are done.