Practice Quiz

ACT Science Exam Prep

Category - ACT Science

Start a Study Session Sign up for Question of the Day

The source of a sound is moving away from an observer who is standing still. How do the sound waves received by the observer compare with those emitted by the source?

  1. They are heard as having a greater velocity.
  2. They are heard as having a higher frequency.
  3. They are heard as having a lower frequency.
  4. They are heard as having a smaller wavelength.
Explanation

Answer: C - Because the sound is moving away from the observer, it takes longer for each sound wave to reach them, increasing the distance between each wave. Since increasing the wavelength of a sound decreases its frequency, the observer will perceive the source of sound as having a lower and lower frequency over time. This phenomenon is called the Doppler effect, and can occur any time the source of a sound moves closer to or further away from an observer. 

Previous Next
Was this helpful? Upvote!
Login to contribute your own answer or details
Start a Study Session Sign up for Question of the Day

Top questions

Related questions

Most popular on PracticeQuiz