Sound+Waves

=Summary= Sound is a pressure disturbance in which it travels through mediums by traveling particle to particle. As it travels it disturbs and displaces adjacent particles carrying the sound waves through it. Sound waves are mechanical waves meaning they are unable to travel through vacuums (empty space) and also sound waves need a medium to transfer the energy.

Sound waves are categorised as longitudinal waves meaning when energy is transported from the wave, the particles are displaced from the particles where the sound is created and to where the sound has met its destination. An example may be a speaker creates sound as the 1st particles that are displaced from the speaker and the last particles which the listener hears. This is longitudinal because the displaced particles are moving back and forth to the destination.

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=Speed of sound= Speed has an initial speed of 340.29 meters per second (34029 centermeters p/s) at sea level. Sound has this speed because when sound is created, it will always displace adjacent particles meaning particles that have been displaced, carry sound out to adjacent particles until the sound waves have run out of energy.

If someone talks loud, the more energy and frequency the sound wave has, therefore it will travel a further distance by displacing more particles, but if someone talks quiet, the less energy and frequency a sound wave has, therefore it will travel a smaller distance because the sound wave is unable to displace more particles.

Inertial properties
The speed of sound waves may be effected by what medium the wave is traveling through. In solids sound waves travel faster than in liquids and in liquids they travel faster than in gases. The greater the density of particles of a medium, the less quick to react to interacting adjacent particles, therefore the wave will be slower.

Elastic properties
A rubber band can be easily deformed or changed in shape when small stress is applied to the rubber band. If a solid for example iron has small stress applied to it, no different formation will occur because it is considered and proven to be rigid. Iron an all solids have atoms and molecules that are highly attracted to each other therefore it has a high elasticity. Solids have very strong interactions with between particles meaning a sound wave may travel through it fast, as for a liquid, it has weak interactions with particles and for gases weaker interactions with particles meaning sound travels through solids faster then liquids and liquids faster then gases.

How fast sound travels in:

- Helium 970m/s - Air 343.3m/s - Water 1482m/s (at a temp of 20 degrees) - Aluminium 5100m/s - Iron 4910m/s - Uranium 3355m/s - Plutonium 2260m/s

Doppler effect
The doppler effect occurs when a sound source creates small wavelength and high frequency usually where it is closest to and a long wavelength with a low frequency usually further away from the sound source. An example may be a dog is repetitively barking, as you walk past it the, the sound waves will be faster and high pitched to you therefore high frequency and small wavelength and as you walk 30 meters away from the dog the sound waves will travel slower and low pitched to you therefore long wavelength and low frequency. It is also important and essential to understand the sound source will always use its own frequency, and the observer will hear at a lower frequency.

=Resonance= Resonance is always achieved if two vibrations creates a loud sound or movement. For example, resonance may be created with a resonance tube (a hollow cylindrical tube). When the vibrating tuning fork vibrates at its own natural frequency, it creates sound waves which impinge within the resonance tube. The impinging sound waves vibrate at the same frequency created by the tuning fork when they enter the tube. The sound waves are unable to discern because they are very silent but when the vibration enters the tube and out the other tube it will create a loud sound, depending on the hertz it will create in-between low and high pitched sounds.



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=Echos= Echos are considered a phenomena of **reflection.** They will always occur when **reflected** upon barriers. These reflections of sound waves travel at a speed of 300 meters per second and when an echo occurs within a medium, they will always be reflected and reflect back to the speaker. We may not realise it, but whenever we talk, an echo always occurs because of reflected sound waves. For example a speaker phone creates noise while it is in the Grand Kenyon, because of all the barriers which surround the sound wave caused and displaced by the speaker phone, the sound wave will be reflected multiple times causing a chain of echos, so few waves will reflect back to the listener, causing a chain of echos.