  We analyze a simple problem in elasticity: the \emph{initial} motion of an
elastic bar that after being hanged from an end is suddenly released. In a
second problem a point mass is attached on the top of the bar. The analytical
solutions uncover some unexpected properties, which can be checked, with a
digital camera or camcorder, in an alternative setup in which a spring is
substituted for the bar. The theoretical model and the experiments are useful
to understand the similarities and differences between the elastic properties
of bar and spring. Students can take advantage of the home experiments to
improve their understanding of elastic waves.
