PURPOSE: To demonstrate resonance and normal modes.

DESCRIPTION: After starting one of the pendula into motion the motion couples back and forth between the two physical pendula at a rate determined by the spring constant and its location. Coupling can be varied by sliding the spring clamps along the pendula shafts, by changing masses, and by changing the positions of the masses. Normal modes can be nicely demonstrated. This is a popular demo with the students.

SUGGESTIONS:

EQUIPMENT: Mounted spring-coupled physical pendula.

SETUP TIME: 30 minutes

KEYWORDS: spring coupled physical pendula