Let's consider how to reduce errors in the ultrasound experiment. We describe a frequency (40 kHz) and measured wavelength. What wavelengths should we measure if we change the frequency to 345 Hz, 3,450 Hz or 345,000 Hz? (Use v=345 m/s for the speed of sound) Please describe which of these measurements would be the most accurate? Why would someone decide to use 40 kHz instead of the frequency leading to the mainly accurate measurement in this experiment?