Chapter 13 Lab 7: Speed of Sound 13.1 Pre-Lab Read this section of the lab manual carefully. Download and install the Phyphox app from your app store. 13.2 Purpose To measure the speed of sound in air using standing sound waves in a pipe. To learn about resonance, and understand the nodes and antinodes in a wave. To compare the measured speed of sound from waves in a pipe to the measured speed of sound using the Phyphox app. 13.3 Introduction Sound is a longitudinal (compressional) wave caused by a vibrating source. Sound travels through a medium by the molecular transfer of energy. In this experiment, you measure the speed of sound in air by examining the resonances of a cylindrical pipe closed at one end. Read Appendix 13.7 at the end of this chapter for a brief discussion on longitudinal waves. The apparatus consists of a long pipe with a plunger inside, and a series of four tuning forks. After being struck with the provided rubber-coated striker, a tuning fork will ring at its characteristic frequency. The tuning fork is held in front of the tube and the plunger in the tube can be