Vibration Nodes of Long Rod

Purpose:
To demonstrate the location of vibration nodes for lowest order mode of flexible rod.

Equipment:
Long flexible metal rod or 3-meter stick

Equipment Location:
Other

Procedure:
Hold long metal rod or 3 meter stick at one end. Vibrate the end up and down. Students should be able to see the location of the node about 1/4 of the length of the rod from either end.

Relevant derivations/explanations:
Knowledge of where the location of the nodes is useful. Baseball players will want to hit the ball near the bat's node so that vibrations are not excited in the bat (at least not the lowest mode vibrations). Also, marimba and xylophone makers support the wood or metal bars at the nodes, so that the rod can freely vibrate in its lowest mode.