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Sound Waves and Pressure. Investigation One. Sounds. Sounds are generated when any solid, liquid, or gas vibrates Vibrations occur when the particles or molecules of matter move repeatedly back and forth Can be fast or slow depending on the object. Vibrations.
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Sounds • Sounds are generated when any solid, liquid, or gas vibrates • Vibrations occur when the particles or molecules of matter move repeatedly back and forth • Can be fast or slow depending on the object
Vibrations • Vibrations in one object can cause other objects close by to vibrate • Since sounds are cause by vibrations the sounds made by the vibrations can also be transferred from one vibrating object to another.
Vibrations • Vibrations that cause sound to travel from one object to another in waves are called pressure waves. • Vibrating objects causes pressure waves in the surrounding air that cause pressure waves in our ear drums allowing us to hear sounds
Pressure Waves • Pressure Waves can occur in all types of matter • Vibrating vocal cords: back and forth movement alternately pushes on the surrounding air and then release it cause alternating high and low pressure in the air.
Frequency • Frequency: back and forth movement of vibrations can occur rapidly or slowly • Vibrations that occur rapidly, occur frequently with a high frequency • Vibrations occur slowly, occur infrequently with a low frequency
Standing Wave • Standing wave- the back and forth motion of vibrating matter • Do not appear to change or travel because the vibrations are fixed in an unchanging pattern • Vibrations alternate back and forth; pressure is alternately placed on the surrounding air producing a pressure wave that produces sound
Standing Waves • The two end points of a standing wave are called nodes. • The middle point is called an antinode
Wavelength • Length of a complete standing wave • Inverse Relationship • If frequency is low then the wavelength is long • If frequency is high then the wave length is short
Producing Sounds • Sounds are produced when matter in the form of a solid, liquid or gas vibrate
Transferring of Sounds from One Object to Another • Vibrations of one object or substance cause pressure waves to impact a neighboring object or substance. • These pressure waves cause the second object or substance to start vibrating
Relationship between Wavelength and Frequency and the Sound it Produces • There is an inverse relationship between wavelength and frequency. • A wave with a high frequency has a short wavelength • A wave with a low frequency has along wavelength
Sound Waves and Pressure Investigation two
Hertz • Hertz- is the unit measure for frequency • Number of vibrations that occur in one second • 1/sec • Frequency of motion of a vibrating object and the frequency of the sounds that it produces are both expressed in Hertz • Human ear can hear between 20 (very low bass) -20,000 (very high pitch Hertz)
Wavelength • Unit of measurement for wavelength is the meter • It is the length of the standing wave of a vibrating object and the length of the pressure wave of the sound vibrations produce
Standing Wave • The speed of a standing wave or a pressure wave has units of meters per second
Relation of Speed, Wavelength, & Frequency • The speed of a wave, its frequency, and its wavelength are all related by • Speed = wavelength X frequency • Meters/second = meters X 1/sec • The speed of sound is always the same in a specific type of matter.
Relation of Speed, Wavelength, & Frequency • Wavelength and Frequency have an inverse relationship • Higher frequency = shorter wavelength • Lower frequency = longer wavelength
Standing Waves • Nodes and Antinodes • Nodes- where the air does not move at all • Antinodes- the vibrating air moves the most
Speed of Sound in Air • Speed of sound in air is approximately 324 meters per second
Speed of sound for different Frequencies and wavelengths • In the same type of matter, the speed of sound does not change if two sounds have different frequencies or different wavelengths
Wavelength and Frequency of a Standing wave • There is an inverse relationship between wavelength and frequency • A wave with high frequency has a short wavelength and a wave with a low frequency has a long wavelength
Sound Wave and Pressure Investigation three
Properties of Matter • Different types of matter possess different properties that can affect how they interact with sound waves • One property is how atoms or molecules of matter are attracted to each other • Greater the attraction between particles results in a greater speed of sound in that matter • Little attraction= lower speed of sound • Speed of sound is greater in solids than in liquids and greater in liquids than gas
Vibrations in Matter • Standing waves cause vibrations in matter that result in pressure waves that travel within in the matter • Pressure waves travel within each type of matter with a certain speed that depends on the attractions between the atoms or molecules
Types of Matter affecting the speed, wavelength, and frequency of sound • The speed of sound changes depending on the type of matter. • Matter that exhibits more attraction between its atoms or molecules will allow sound to travel at greater speeds. • Matter that exhibits less attraction between its atoms or molecules will allow sound to travel at lower speeds. • Different types of matter will cause a change in the wavelength of a sound wave but the frequency of the sound wave will not change
