Temperature-Compensated Pendulum Clock · CAP 2011 #B2
Physics · thermodynamics
Problem
Photo A shows a pendulum for a grandfather clock. It consists of very thin sets of iron and zinc rods and the pendulum bob. At room temperature there is one iron rod of length L0Fe=68.00 cm, two iron rods of length L1Fe and two zinc rods of length LZn connected as in diagram B. Both sets of rods are of negligible weight compared to the pendulum bob. The thickness of the connecting pieces is negligible compared to the length of the rods. The bob is attached to the iron rod. The pendulum length, then is L=L0Fe+(L1Fe−LZn), L = 70.00 cm.
(a) Does the position of the rods in diagram B correspond to a warmer day or a colder day compared to their position in diagram C?
(b) Find L1Fe and LZn if the pendulum period does not change when the temperature changes.