Question

which statement accurately describes how the understanding of the doppler effect is applied to the study of galaxies?
it was used by hubble to measure the velocities of galaxies.
it was used to monitor galaxy motion through changes in sound waves.
it indicates a galaxy moving toward earth through red shift.
it indicates a galaxy moving away from earth through blue shift.

Explanation:

• Galaxies emit light, not sound waves, so the sound wave option is incorrect.
• A red shift occurs when a galaxy moves away from Earth, and a blue shift occurs when it moves toward Earth, so the shift-direction matching options are reversed and wrong.
• Hubble used the Doppler effect (via redshift measurements) to calculate galaxy velocities, establishing the Hubble law.

Answer:

It was used by Hubble to measure the velocities of galaxies.