Question

The Doppler shift can be observed when _______ . Select all that apply.Group of answer choicesa- an observer moves away from a stationary sound sourceb- an observer moves towards a stationary sound sourcec- the source of sound moves away from an observerd- the observer and sound source move at the same speed in the same directione- the source of sound moves towards an observer

Answer 1

a, b, c, and e

Step-by-step explanation

The Doppler shift - also called the Doppler effect, is the alteration in a wave's observed frequency due to the relative motion between the observer and the source.

Let's analyze the options:

• a. an observer moves away from a stationary sound source, → the observer is in motion

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• b. an observer moves towards a stationary sound source, → the observer is in motion

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• c. the source of sound moves away from the observer, → the source is in motion

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• d. the observer and the sound source move at the same speed in the same direction, → both are moving at the same speed in the same direction

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• e. the source of sound moves towards an observer, → the source is in motion

For options a, b, c, and e, there is a relative motion between the source and the observer. In all cases, they are either coming closer or separating.

For option d, where both are moving in the same direction at the same speed, there is no change in the distance between them. This is like they were both stationary, because there is no relative motion and, therefore, we cannot observe a Doppler effect in this case.

Hence, the Doppler shift can be observed only in scenarios a, b, c, and e.