1. The problem statement, all variables and given/known data A runner is running with speed V along the straight line connecting two identical speakers. Both speakers are playing a tone of the same frequency f. a)What is the beat frequency that the runner hears? b)If the standing wave forms between two speakers, how frequently will the runner hit a node of the standing wave? c)Compare your results from (a) and (b). 2. Relevant equations fl = fs(v+Vl)/(v+Vs), where v is the velocity of the wave, Vs is the velocity of the source and Vl is the velocity of the listener. v = λƒ 3. The attempt at a solution I solved part a using the doppler effect equation. Tbeat = Vf/2v For part b, I got the answer Vf/4v. Because it is two open ends, the start of the wave is an displacement antinode and thus the displacement node is at every λ/4. But according to the answer it seems that the node they are referring to is the pressure nodes which are the displacement antinodes, thus the displacement antinodes is at every λ/2 which gives the answer Vf/2v which is the given answer. So am I correct that the question refers the node as an pressure nodes? Or are they referring to the displacement nodes thus my concept is a bit shaky.