I was trying to do this problem over on this quiz:
"You are watching a marching band practice outdoors. Near you are two trumpet players, one marching directly towards you and one away from you at the same speed. Each trumpet player is playing an A (440 Hz) and you hear a beat between the two sounds at a frequency of 2 Hz. How fast are the trumpet players marching in m/s?
Details and assumptions
The speed of sound is 340 m/s. The trumpet players aren't moving very fast."
I first made the expression for the shifted wavelengths by thinking about 2 peaks on the original wave and noted that the second peak would be off by the velocity of the source times the period, so I can up with this
I would like to know if I did this correctly.
After that, I got lost (and consequently frustrated; if you can, please give tips on how to deal with that as well.) because I didn't understand what the 2 Hz part means: does it mean that a peak from either waves occurs every half-second or does it mean that the peaks coincide every half-second?
Please tell me.