This physics problem appeared in my Calculus book:

Given a rod with length $\displaystyle a$ it is hindged thus it can freely rotate. An object is attached to the end of the rod and it is brough all the way vertically up. Then a slight disturbance and it flys down (from equilibrium). How long does it take for it to come down to the minimum point? Just remember it travels in a circular motion.

My book gave the answer:

$\displaystyle \sqrt{\frac{a}{g}}\ln{(1+\sqrt{2})}$

Where $\displaystyle g$ I am guessing it the gravitational acceleration.