What specific measurement does the Doppler shift quantify?

Answer

Relative motion (approach or separation speed)

The key takeaway of the Doppler shift is that it quantifies relative motion, specifically the speed at which two objects are either approaching or separating from each other.

What specific measurement does the Doppler shift quantify?

#Videos

Doppler Effect - How Motion Changes Sound Frequency - YouTube

frequencymotionDopplerwavereveal