Asource and observer are moving relative to one another: one is at rest, and the other is moving at some speed less than the speed of sound (the goal of the problem is to figure out who is moving). the source emits sound waves at frequency fo, but the observer detects the sound at frequency 3fo. what is the wavelength of the sound waves, as measured by a third person who is at rest and is located somewhere between the source and receiver? your answer will have v (the speed of sound) as well as check to make sure that the combination you write down has the right dimensions/units for length/meters.