Speed of Sound Propagation

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Introduction to Speed of Sound Propagation

We hear various types of sounds every second. It can be from the instruments, the sound of thunder, and the list goes on and on. But what is sound? How does it take place? How is the sound created? How does the sound propagation take place? Let us provide you with the answer to all these. We provide the students with the notes of sound propagation to help them clearly understand the phenomenon taking place and the science behind it. Moreover, they will also understand how sound travels through different mediums and the process that follows. These notes are available in PDF download form and make the study process easier for the students. 

What is Sound? 

In simple words, the sound is nothing but a form of energy just like heat, electricity, etc. Consider an example of a source of the sound, such as a bell. Whenever we strike a bell, it creates a sound. What accompanies the sound is the vibration, which causes to and fro motion of the object’s body. 

Sound is the vibration that transmits through mediums like solid, liquid, and gas by the alternate contraction and expansion of the medium in the form of an acoustic wave

Characteristics of Sound

The pictorial representation of sound is in the form of continuous peaks and valleys. The distance covered between two continuous peaks or troughs is called the wavelength of the wave. The frequency of sound is defined as the number of cycles covered per unit of time. It is measured in Hertz.

What is the Speed of Sound?

It is defined as the dynamic propagation of waves taking place through different mediums. The speed of sound varies depending on the medium through which it propagates. When talking about sound speed, we refer to the speed of the sound waves when travelling in an elastic medium. 

The formula for the speed of with respect to gases is as given:

𝜈= √𝛾P/𝜌

𝜈 represents the speed of sound

𝛾 is used as the coefficient of adiabatic expansion 

P represents the pressure of the gas

𝜌 represents the density of the medium in which sound travels

Factors Affecting The Speed of Sound

The factors on which the speed the sound majorly depends are:

  • The Density of Medium: Sound requires a medium to travel. The density of the medium is among the factors which affect the speed of sound. The higher the density, the faster the sound travels through the medium. And, on the other hand, the lower the density, the slower is the speed of propagation of sound. This means that the speed of sound in different mediums varies directly with the density of the medium. 

  • The Temperature of The Medium: Higher the temperature, the higher is the speed of sound in the medium. 

Speed of Sound in Different Media

Sound can travel through different mediums, and here is how it propagates through them:

Speed of Sound in Solid

The sound travels in solids through the collision between different molecules and particles. Solids have a higher density in comparison to other mediums, making the speed of sound high. In solids, the speed of sound is approximately 6000m/s.

Speed of Sound in Liquid

The density of liquids is lower than solids and higher than gases. This leads to the speed of sound in liquids lying between the speed of solids and gases. 

Speed of Sound in Gases

The speed of sound in gases is irrespective of the medium. This is because of the uniformity in the density of gas irrespective of its type.

Speed of Sound in a Vacuum

Sound doesn't travel through a vacuum, making its speed zero. This happens because of the absence of particles in a vacuum. No propagation of sound waves takes place in a vacuum. 

FAQ (Frequently Asked Questions)

1. What is the intensity of sound?

The energy that goes through a unit area at that point is defined as the intensity of sound. The intensity of sound varies inversely with the square of the distance between the source and point. The intensity of sound also varies directly with the square and frequency of vibration and the medium's density.

2. Why is the speed of sound is maximum in solids?

The speed of sound is maximum in solids because of the concentration of particles. The particles are closely packed, moving sound propagation faster. For example, sound travels at a speed of 5100m/s in steel. This itself justifies why the speed of sound is maximum in solids.

3. On what factors does the speed of sound in a gas depend?

It depends on two factors, namely, elasticity and density of the gas.