PURPOSE: To illustrate transverse vibrations of a solid bar struck in the center.

DESCRIPTION: When struck on top center with a rubber mallet, like a xylophone or marimba, the narrower bar on the right in the photograph above vibrates with a frequency f (click here for video). Q: Will the frequency of the larger bar on the left, which has the same length and thickness as the smaller bar, but twice the width, be greater than, less than, or the same as the frequency of the smaller bar? A: The frequency will be the same for transverse vibrations (click here for video).

SUGGESTIONS: Ask the students before doing the experiment.

See Question of the Week #48 for information on using this demonstration to enhance class involvement.

REFERENCES: (PIRA unknown.)

EQUIPMENT: Two machinist's parallels, 6"x1/4"x1/2" and 6"x1/4"x1", rubber support blocks, and mallet.

SETUP TIME: None.