In: Physics
A certain ultrasound device can measure a fetal heart rate as low as 50 beats per minute. This corresponds to the surface of the heart moving at about 4.0 x 10-4 m/s. If the probe generates ultrasound 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.