Suspended Rod On Water

Purpose

An elementary problem involving horizontal friction.

Equipment

String and stick assembled on stand, styrofoam chip, and pan of water, as photographed.◙

Suggestions

Ask your class to vote on the result before doing the experiment.◙

Setup Time

5 min

Images

c6-21

Description

The top end of a rod is supported by a string connected to a fixed point, with the bottom end floating freely on a small piece of styrofoam on the surface of the water. Which of the three drawings below best portrays the equilibrium position of the system: (a), (b), or (c).◙