The driver of a car traveling 24.0 m/s sounds his horn as he approaches an intersection. If the horn has a frequency of 655 Hz, what frequency does a pedestrian hear, if she
Properties of sound
A sound wave is a mechanical wave (or mechanical vibration) that transit through media such as gas (air), liquid (water), and solid (wood).
Quality Of Sound
A sound or a sound wave is defined as the energy produced due to the vibrations of particles in a medium. When any medium produces a disturbance or vibrations, it causes a movement in the air particles which produces sound waves. Molecules in the air vibrate about a certain average position and create compressions and rarefactions. This is called pitch which is defined as the frequency of sound. The frequency is defined as the number of oscillations in pressure per second.
Categories of Sound Wave
People perceive sound in different ways, like a medico student takes sound as vibration produced by objects reaching the human eardrum. A physicist perceives sound as vibration produced by an object, which produces disturbances in nearby air molecules that travel further. Both of them describe it as vibration generated by an object, the difference is one talks about how it is received and other deals with how it travels and propagates across various mediums.
![**Problem: Doppler Effect with a Car Horn**
**Context:**
A car is traveling toward an intersection at a speed of 24.0 meters per second (m/s). The driver sounds the car's horn, which emits a sound at a frequency of 655 Hertz (Hz). There is a pedestrian standing at rest at the intersection's crosswalk. The speed of sound is given as 343 meters per second (m/s).
**Objective:**
Determine the frequency heard by the pedestrian due to the Doppler effect.
**Explanation:**
When the source of a sound is moving towards an observer, the observed frequency increases. The formula to calculate the observed frequency (f') when the source is moving towards a stationary observer is as follows:
\[ f' = \frac{f \cdot (v + v_o)}{v - v_s} \]
Where:
- \( f' \) = observed frequency
- \( f \) = emitted frequency of the source = 655 Hz
- \( v \) = speed of sound in the medium = 343 m/s
- \( v_o \) = speed of the observer (0 m/s in this case, as the observer is stationary)
- \( v_s \) = speed of the source = 24.0 m/s
Since the observer is stationary (\( v_o = 0 \)), the formula simplifies to:
\[ f' = \frac{f \cdot v}{v - v_s} \]
Using the given values, we can calculate the frequency heard by the pedestrian.](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2F59577f62-52f2-4d8a-8fce-f8969dac81ff%2F7dd8e72c-1de4-4c11-84f3-09a8c957c8c2%2F3mzilhc5_processed.png&w=3840&q=75)
Step by step
Solved in 2 steps with 2 images
