Things I Should Know About Sound

If you are a Grade 8 Student and you are here to have an advance reading of your lesson on sound, probably you have to consider these important things to review on from your previous lesson in Grade 7. What are the things you should know about sound before tackling the Most Essential Learning Competency (MELC) investigate the effect of temperature to the speed of sound.

What is Sound?

Sound is a traveling disturbance which carries with it energy. Sound is a form of energy and a wave. The energy of sound (or sound per se) is transmitted by vibrations of the medium at which the sound travels. 

Sound is a form of energy that is perceived by the ear. It is audible. However not all sound frequencies could be perceived by the human ear. There are sound that we could not hear! Our human ear is sensitive only to sounds that are within 20 hertz to 20,000 hertz. Sound that have frequencies below 20 hertz are called infrasonic sound. Sound with frequencies above 20,000 hertz are called ultrasonic sound.

What kind of wave is sound wave?

Sound is a mechanical wave. Sound are produced and transmitted by vibrations of particles of a medium. Without a material of medium at which sound could travel, transmission of sound is impossible to happen. 

There are two types of mechanical wave - transverse and longitudinal wave. Sound falls under the second category. Sound is a longitudinal wave. This means that the particles of the medium at which sound travels vibrate back and forth at fixed positions. The vibration of the particles are parallel to the direction of the wave motion.

In what type of material does sound travel?

Sound travel in any type of matter. This means that sound can travel in solid, in liquid, and in gas! The speeds of sound however in these three media ( or material) are not the same. A given sound for example with a specific wavelength and frequency travel faster in solid than in liquid. In fact, sound travel fastest in solid (particularly metals) and slowest in gases. This is mainly because of the arrangement of particles in these three types of matter. Since the particles of solids are arranged closely together, the energy is easily transmitted to the neighboring particles.

What composes a sound wave?

Sound wave is composed of compressions and rarefactions. As particles of the medium oscillate, the particles rearrange themselves into a localized region of high pressure and low pressure. Compression is a localized region of high pressure because the particle move closer to one another. Rarefaction on the other hand is a localized region of low pressure due to the spreading out of particles from one another. These regions of compressions and rarefactions occur alternately are particles of the medium vibrate back and forth.

How to compute for the speed of sound?

Since sound is a wave, the speed of sound could be computed using the speed of wave equation, v = λf where v is the speed, λ is the wavelength and f is the frequency. Frequency is the number of waves produced in a second. If a wave has a frequency of 90 Hz (hertz), it means that the wave produces 90 complete waves in a second. Frequency is inversely related to Period. Period is the time it takes for one complete wave to be produced. Since 90 hertz wave produces 90 waves in a second, it takes 1/90 or 0.011 second to produce one complete wave. This means that the period of this wave is 0.011 second. Period (T)  could be computed as T = 1/f.

Since T = 1/f, the formula could be rearranged to compute for frequency. Frequency f = 1/T. 

Since v = λf and f = 1/T, the speed of the sound wave could also be computed as v = λ / T.

What other factors affect the speed of sound wave?

Since sound is a mechanical wave, the speed of sound depends greatly on the medium at which it is propagated or transmitted. In other words, speed of sound depends on the nature of the material at which it travels. There are three factors affecting the speed of sound in a material. These factors are elasticity of the material, the density of the material and the temperature of the material at which sound travels.

Now that you have learned the basic information you should know about sound, you are now ready to study the effect of temperature on the speed of sound particularly in air.

See you with our next lesson!

Comments

Post a Comment

Popular posts from this blog

Why Blue is Hotter than Red?

Image
Why Blue is Hotter than Red? by E. Pasion   Poets say “red hot” and “cold as blue”. In arts, warm tones are associated to red, orange and yellow while cool tones are that of the opposite end of the color spectrum – blue and violet.   However, isn’t it contradicting to what scientists say? The hottest stars for example are the blue hypergiant ones while the coolest ones are the red stars!    Which color really has the highest energy? Which one has the least?   To answer that boggling question, we need to review the color spectrum of the visible light!     What is light?   White light is the combination of all colors in the electromagnetic spectrum. Light is the presence of all colors while black is the absence of all of it! As you have learned in Grade 7, light is a part of the electromagnetic wave or the EM wave! The EM wave is composed of seven different components. These components (in increasing energy) are radio wave, microwave, infrared, visi...
Read more

Why it Sounds Noisier on a Hot Day?

Image
What happens to sound on a hot day? Does air temperature affect speed of sound? Why it sounds noisier on hot weather conditions? Sound is a traveling disturbance that travels through matter - solid, liquid or gas. It is a mechanical wave that is propagated by the vibrations of particles in a medium. A medium is the material at which wave travels.  Sound is a longitudinal mechanical wave . A longitudinal wave is a type of mechanical wave that propagates by compression and rarefaction.   Compression is a region of high pressure where particles of the medium are forced to compress or move closer together. Rarefaction , on the other hand, is a region of low pressure where the particles of the medium are rarefied or move farther away from each other. Particles of a medium in longitudinal wave vibrates back and forth parallel to the direction of the wave. The wavelength of a longitudinal wave is the distance measured from one compression to the next compression or from one rarefact...
Read more