A Hot Pendulum

If the length $12.42\,cm$ prove to be to short for a sustained swing,

$f_{res}=\cfrac{1}{2\pi}\sqrt{\cfrac{g}{4l}}=\cfrac{1}{2}*\cfrac{1}{2\pi}\sqrt{\cfrac{g}{l}}=\cfrac{\sqrt{2}}{2}$

a length of $4*l=49.68\,cm$ at half the required frequency might swing a bit longer.

Maybe...