A certain ultrasound device can measure a fetal heart rate aslow as 50 beats per minute. This corresponds to the surface of theheart moving at about 4.0 x 10-4 m/s. If the probe generatesultrasound that has a frequency of 2.0 MHz (1 MHz = 1 megahertz =106 Hz), what frequency shift must the machine be able to detect?Use v sound = 1540 m/s for the speed of sound in human tissue.
