Describes a ripple tank demonstration that displays interference patterns responsible for producing beats and provides photographs of computer simulations of various beat interference patterns. Includes programs for the computer simulation and equations of constructive interference paths in beat interference patterns. (Author/SK)

Describes apparatus, computer program (for Apple II), and procedures used in an experiment to determine the velocity of sound in air. In addition, the experiment focuses on the attention required in calibrating equipment and the measuring of both long distances and very short time intervals. (JN)