TOPIC:

ID Code: C6-21
Purpose: An elementary problem involving horizontal friction.
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, depicted above, best portrays the equilibrium position of the system: (a), (b), or (c)?
Availability: Available

See the Physics Question of the Week for 5/5/2014 for an example of how this demonstration can be used in class interaction and discussion: lecdem.physics.umd.edu/question-of-the-week-archive.html