This physics problem appeared in my Calculus book:
Given a rod with length 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:
Where I am guessing it the gravitational acceleration.