1. The problem statement, all variables and given/known data 1. On a long trip that you take to forget for a while about physics, you find yourself driving directly towards a canyon wall. You’ve previously noticed that your car horn has a frequency of 440 Hz. You glance at the speedometer and notice you’re moving at 30 km/h. (8.333...m/s) What is the beat frequency you experience? 2. Relevant equations Various Doppler Effect Equations and Beat Frequency 3. The attempt at a solution I need to calculate the beat frequency for this question, to do that I need both frequencies from the reflection of the wall and the sound I hear from the horn itself. Is it correct to treat the wall as its own source? Therefore I am traveling towards the source? What about the second doppler effect? I am struggling to figure it out. It is me traveling towards the source again? That wouldnt make sense as I am traveling to two sources? ahh im stuck. (How does the frequency change when I am traveling with the source?) Thanks!