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.
Shown below is a stationary source and moving observers. Describe the frequencies observed by the observers for this configuration.
Given data
The velocity of the source is vs=0
The velocity of the first observer is v1
The velocity of the second observer is v2
The velocity of the third observer is v3=v1
The expression for the observed frequency is,
Here fo is absorbed frequency.
fs is source frequency.
v is the speed of sound
vo is the velocity of the observer.
vs is the velocity of the source.
A positive sign is used in both numerator and denominator if the observer moves towards the stationary source from the above formula.
As in the given case for the first observer,
The expression for the observed frequency is,
It is observed that in this case, the observed frequency is lower than the source frequency.
Thus, the frequencies observed by the first observer for this configuration is lower than the source frequency.
Step by step
Solved in 4 steps
