Sound Waves and Pressure

1. Sound Waves and Pressure

2. Investigation One

3. 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

4. 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.

5. 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

6. 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.

7. 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

8. 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

9. Standing Waves • The two end points of a standing wave are called nodes. • The middle point is called an antinode

10. 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

11. Producing Sounds • Sounds are produced when matter in the form of a solid, liquid or gas vibrate

12. 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

13. 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

14. Sound Waves and Pressure Investigation two

15. 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)

16. 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

17. Standing Wave • The speed of a standing wave or a pressure wave has units of meters per second

18. 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.

19. Relation of Speed, Wavelength, & Frequency • Wavelength and Frequency have an inverse relationship • Higher frequency = shorter wavelength • Lower frequency = longer wavelength

20. Standing Waves • Nodes and Antinodes • Nodes- where the air does not move at all • Antinodes- the vibrating air moves the most

21. Speed of Sound in Air • Speed of sound in air is approximately 324 meters per second

22. 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

23. 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

24. Sound Wave and Pressure Investigation three

25. 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

26. 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

27. 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