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Course: MCAT > Unit 3

Lesson 1: Foundation 4: Physical and chemical principles

Sound: How movements influence an ultrasound


Ultrasound imaging is a medical technique utilized to examine inner tissue and organs of a patient. The technique is particularly useful in pregnancy imaging, as it provides a non-invasive yet thorough visualization of fetal and maternal information. This evidence then informs decisions involving dating the pregnancy, potential birth complications, and consistent monitoring of the mother’s health.
The machine first produces a sound wave, which travels into the patient. The wave’s particles are reflected or redirected in different patterns depending on the type of body tissue it comes in contact with. The sound wave then returns to the ultrasound machine, which converts the auditory information into an electrical image that is displayed on a monitor.
Scientists are interested in learning the effects of movement on ultrasonography. To study this in further detail, they place the machine on a moving apparatus. The machine emits a sound wave at the patient, who is standing a certain distance away. In order to gather further information, the scientists provide the patient with a device to measure the intensity and frequency of the waves. The new image is then compared to one in which the patient and ultrasound machine are both still.
Figure 1. A diagram of the apparatus the scientists used.
In one trial, the machine moves towards the patient with a constant speed v. While this is occurring, which of the following descriptions is most accurate?
Choose 1 answer: