Two objects are moving directly away from an observer at the same speed. One object, however, is twice as far away as the other. How do their Doppler shifts compare?
A) They are the same.
B) The more distant object has the greater Doppler shift.
C) The more distant object has the smaller Doppler shift.
D) Whichever object is larger will have the greater Doppler shift.

Question

Quizplus · Accepted Answer

The Doppler shift depends on the relative speed between the observer and the source, not the distance of the source from the observer. Since both objects are moving away at the same speed, their Doppler shifts will be the same, regardless of their distances.

Two Objects Are Moving Directly Away from an Observer at the Same