1. The problem statement, all variables and given/known data Imagine a row of many small volumes of air (each consisting of many billions of molecules) along the entire length of a tube that is open at one end. Describe the motion of these small volumes of air when the standing wave, represented by Fig2 (sound wave in a closed tube), is produced. Which of the small volumes of air along the tube move fastest/slowest? What is the direction of motion (along the tube or perpendicular to it)? 2. Relevant equations none 3. The attempt at a solution The volumes of air at the highest wave amplitude will move the fastest. The molecules will vibrate parallel to the direction of the wave. Is this correct? Thanks for any input.