You know you watch too much Doctor Who when....
You use this as a example problem in a physics lecture you taught last semester:
A man in a blue suit enters a tall tower and needs to know the height of the building. He notes a pendulum extends from the ceiling to almost the floor and has a period of 12.0 seconds.
(a) Find the length of the pendulum, thus finding the height of the building.
(b) Now suppose the building is transported to the moon (g = 1.67 m/s^2) by an extraterrestrial species of mercenary police that have giant rhinoceros heads. Find the period of oscillation.