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Solved: BIO Ultrasound in Medicine. A 2.00-MHz sound wave
Chapter 16, Problem 74P(choose chapter or problem)
Problem 74P
BIO Ultrasound in Medicine. A 2.00-MHz sound wave travels through a pregnant woman’s abdomen and is reflected from the fetal heart wall of her unborn baby. The heart wall is moving toward the sound receiver as the heart beats. The reflected sound is then mixed with the transmitted sound, and 72 beats per second are detected. The speed of sound in body tissue is 1500 m/s. Calculate the speed of the fetal heart wall at the instant this measurement is made.
Questions & Answers
QUESTION:
Problem 74P
BIO Ultrasound in Medicine. A 2.00-MHz sound wave travels through a pregnant woman’s abdomen and is reflected from the fetal heart wall of her unborn baby. The heart wall is moving toward the sound receiver as the heart beats. The reflected sound is then mixed with the transmitted sound, and 72 beats per second are detected. The speed of sound in body tissue is 1500 m/s. Calculate the speed of the fetal heart wall at the instant this measurement is made.
ANSWER:Solution 74P
If v is the magnitude of the heart wall speed,V is a speed of sound and is the frequency the heart receives (and reflects),
is original frequency and
is reflected back.
Consider here heart is moving observer and device is stationary source.
In Second part Heart is moving source and device is stationary observer.
From above two equation we can defines beats by