An object is observed to show no Doppler shift. As a result, only one of these statements cannot describe the motion of the object. Which one?
A) The object is stationary.
B) The object has only a transverse motion.
C) The object has only a proper motion.
D) The object has only a radial motion.

Question

Quizplus · Accepted Answer

The Doppler shift is observed when there is motion along the line of sight between the observer and the object, known as radial motion. If an object shows no Doppler shift, it means there is no motion towards or away from the observer. Options A, B, and C do not necessarily involve radial motion towards or away from the observer, but option D, radial motion, would result in a Doppler shift if it were present.

An Object Is Observed to Show No Doppler Shift