Understanding the Doppler Effect Equation: Velocity and Frequency Relationship

Click For Summary

Homework Help Overview

The discussion revolves around the Doppler Effect equation, specifically focusing on the relationship between velocity and frequency as a person travels towards a wall while using a tuning fork. Participants are exploring the implications of the observer's and source's velocities in the context of the equation.

Discussion Character

  • Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants are questioning the signs of the observer's and source's velocities in the Doppler Effect equation, particularly when the observer is also the source. There are discussions about treating the wall as a source and the implications of whether the observer is stationary or moving.

Discussion Status

The discussion is ongoing, with participants raising various interpretations of the Doppler Effect. Some have offered insights into the nature of sound waves in different scenarios, while others are seeking clarification on the correct application of the equation. There is no explicit consensus yet on the correct approach.

Contextual Notes

Participants are grappling with the assumption that observers are always stationary, which has been challenged in the context of the problem. The differences in frequency perceived based on the relative motion of the source and observer are also under examination.

dekoi
Suppose a person is traveling towards a wall with a tuning fork at frequency 'f' at a speed of 'v*'. Using the doppler effect equation:
f' \ = \frac{v + v_o}{v - v_s}

What would the sign of v_o and v_s be? I don't understand, since the man is both the observer and the source. (Let - be receeding and + be approaching).
 
Last edited by a moderator:
Physics news on Phys.org
Treat the wall as a source which is approaching the observer. Remember that observers are aways stationary.
 
Integral said:
Remember that observers are aways stationary.

Observers aren't always stationary though. The effect will be different if the wall approaches him than if he approaches the wall.
 
So which is the correct answer??
 
d_leet said:
Observers aren't always stationary though. The effect will be different if the wall approaches him than if he approaches the wall.
Why? (to b, not to a)
 
berkeman said:
Why? (to b, not to a)

Because if the sound is moving then the waves will be closer together or farther apart than if the sound is staionary.
 
No. In an approaching situation, the waves are compressed no matter what.
 
berkeman said:
No. In an approaching situation, the waves are compressed no matter what.

but if f is the frequency of the source.

then f(1+ v/v_sound) is noth the same thing as f/(1 - v/v_sound) the equations are different for each situation so the frequencies heard by the listener will be different in each case.
 

Similar threads

Range of frequency heard by observer related to Doppler effect
  • · Replies 8 ·
Replies
8
Views
1K
Speed of moth related to Doppler Effect
  • · Replies 8 ·
Replies
8
Views
1K
Moving Source, Observer at Rest, derivation for Doppler effect
  • · Replies 2 ·
Replies
2
Views
2K
Changing of frequencies in the Doppler effect
  • · Replies 3 ·
Replies
3
Views
1K
How do you calculate wind speed using the Doppler effect?
  • · Replies 4 ·
Replies
4
Views
4K
Understanding the Doppler Effect: Solving the Bat Problem
  • · Replies 1 ·
Replies
1
Views
5K
Doppler effect: why do I find this exercise so difficult?
  • · Replies 5 ·
Replies
5
Views
2K
Blood flow velocity via Doppler effect
  • · Replies 1 ·
Replies
1
Views
2K
Undergrad Deriving Doppler Effect Frequency w/ Stationary Person & Moving Source
  • · Replies 3 ·
Replies
3
Views
2K
Calculating frequencies with the Doppler Effect
  • · Replies 1 ·
Replies
1
Views
3K