1. Warm-Up: March 27th 1.What are the two types of mechanical waves? 2.Sound is what kind of wave? 3.What is the topmost part of a transverse wave called? 4.What makes up the wavelength of a longitudinal wave (what two parts)? 5.If you can see the light coming from another room (not directly), the lightwaves are bending. What do we call that?

2. Sound Waves Longitudinal – Disturbance of medium is parallel to wave movement Disturbance of medium is parallel to wave movement MUST have a medium to travel in MUST have a medium to travel in

3. Wave Speed Velocity of a wave is calculated by multiplying wavelength by frequencyVelocity of a wave is calculated by multiplying wavelength by frequency V w = x f f V *As f increases, decreases!

4. Example Problem 1: A wave is generated in a wave pool at an amusement park. The wavelength is 3.2 m and the frequency is 0.60 Hz. What is the velocity of the wave?A wave is generated in a wave pool at an amusement park. The wavelength is 3.2 m and the frequency is 0.60 Hz. What is the velocity of the wave? V = x f V = x f 1.92 m/s

5. Example Problem 2: Earthquakes can produce three types of waves. One of these is a transverse wave called an “s” wave. A typical s wave travels at 5000 m/s. Its wavelength is 417 m. What is its frequency?Earthquakes can produce three types of waves. One of these is a transverse wave called an “s” wave. A typical s wave travels at 5000 m/s. Its wavelength is 417 m. What is its frequency? F = 12 HzF = 12 Hz

6. Example Problem 3: A sound wave has a frequency of 500.0 Hz and a wavelength of 3.0 m. What is the speed of the wave?A sound wave has a frequency of 500.0 Hz and a wavelength of 3.0 m. What is the speed of the wave? V = x f

7. Example Problem 4 The lowest-pitched sounds humans can hear have a frequency of 20.0 Hz. What is the wavelength of these sound waves if their wave speed is 340.0 m/s?The lowest-pitched sounds humans can hear have a frequency of 20.0 Hz. What is the wavelength of these sound waves if their wave speed is 340.0 m/s? V = x f

8. Warmup March 28 th Happy Spring Break!! 1.What kind of waves are sound waves? A.Longitudinal B.Electrical C.Transverse D.Both A and B

9. 2. As frequency of a wave Increases, the length of a wave ___________(if velocity is same) A.Increases B.Stays the Same C.Decreases

10. 3. Sound travels fastest through A.Solid B.Liquid C.Gas

11. 4. Frequency of a wave determines a sound’s A.Amplitude B.Pitch C.Intensity

12. 5. What is the Frequency of a sound wave traveling 330m/s (in the air) with a wavelength of.55 meters? A.1550 Hz B.800 Hz C.775 Hz D. 600 Hz

13. ANSWERS TO WARMUP 1.A2.C3.A4.B5.D

14. Frequency and Pitch Pitch: The highness or lowness of soundPitch: The highness or lowness of sound Depends on the frequency Depends on the frequency High frequency = high pitchHigh frequency = high pitch Low frequency = low pitchLow frequency = low pitch 20,000 Hz: ultrasonic waves 20,000 Hz: ultrasonic waves 20 Hz and below: infrasonic waves 20 Hz and below: infrasonic waves

15. Intensity and Loudness Loudness: Human perception of sound intensity.Loudness: Human perception of sound intensity. Depends on the amplitudeDepends on the amplitude Decibel Scale (dB) - Measures intensity of sound

16. Waves go through mediums, and different mediums are transparent to different types of wave energy. But also, a wave’s energy can be partly or completely absorbed by the different medium When Waves Hit Things

17. Sound – as Waves Amplitude = volume Frequency = pitch. High frequency, high pitch. Low frequency, low pitch. Must have a medium – no medium, no sound. Sound waves – What type of medium do they travel fastest through (solid, liquid, gas)?

18. Measuring Sound Decibel – a measure of the Sound Pressure Level. The higher the decibel, the more intense the sound.

19. Whisper Quiet Library at 6'30dB Normal conversation at 3'60-65dB City Traffic (inside car)85dB Level at which sustained exposure may result in hearing loss 90 - 95dB Power mower at 3'107dB Listening to music with headphones 105-120 dB (earbuds add 6- 9 dB) Pain begins125dB 12 Gauge Shotgun Blast165dB Death of hearing tissue180dB Loudest sound possible194dB

20. It happened to my uncle…he was one of the first people I ever knew to own a “SONY WALKMAN” He listened at very high volumes pretty much all day…now he is pretty much deaf……and it’s very much annoying for us and him!

21. DID YOU HEAR WHAT I SAID??? DON’T LET THIS HAPPEN TO YOU!!!!!!!!

22. August 27, 1883 Krakatoa 180 dB Loudest sound ever heard. The sound itself caused tsunamis

23. The Doppler Effect The What????? Where have you heard the term “doppler” before? http://www.youtube.com/watch?v=h4OnBYrbCjY&authuser=0 http://www.youtube.com/watch?v=Djz_rtnXSfY&authuser=0

24. The Doppler Effect A change in the observed frequency of a wave when the source and observer (you) are in motion relative to each other. The frequency appears to increase as the source get closer, and appears to decrease as it moves away.

25. Cool sound stuff… Supersonic (faster than the speed of sound) Subsonic (slower than the speed of sound) Sonic boom (what happens when you pass the speed of sound) Infrasound (below 20 Hz)

26. Sound Waves Carry Energy!! https://www.youtube.com/watch?v=BE827 gwnnk4 https://www.youtube.com/watch?v=BE827 gwnnk4

27. Calculate the Wavelength of 3 different tuning forks Speed of sound in air is 330m/s The frequency of each fork is printed on the stem Calculate the wavelength of three different tuning forks. 256, 312, 680 V w = x f