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Physical Science

This chapter discusses the characteristics of waves, including transverse, longitudinal, and surface waves. It also covers important properties such as frequency, wavelength, speed, and amplitude. The chapter includes information on reflection, refraction, and diffraction of waves, as well as the concepts of interference, standing waves, and the Doppler effect. It concludes with an explanation of sound waves, hearing, and musical instruments.

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Physical Science

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  1. Physical Science Chapter 17 NOTES Mechanical Waves and SOUND (Characteristics of Waves)

  2. What are waves? • Wave – when energy moves through a medium as a vibration • Medium – the material through which a wave passes • Waves travel through the medium without actually moving the medium with it. • 3 main types • Transverse • Longitudinal • Surface

  3. Transverse Waves • Cause the medium to vibrate at right angles to the direction the wave travels • Has a crest (top) and trough (bottom) • Draw this!!! • Example – ripple on a pond • Transverse Wave Video clip • Wave animation

  4. move particles parallel to the direction the wave is moving, “push-pull” waves. Example – sound waves in air Draw this! Video clip transverse vs. longitudinal waves Has compression and rarefaction (decompression) Longitudinal Waves

  5. Grandpa John – Wave Motion • List examples of each type of wave as you watch the video. • So, Examples of Transverse? • Radio and light • Examples of Longitudinal? • Sound and earthquakes

  6. Travel on a surface separating 2 media object on the surface moves in circles - a combo of transverse and longitudinal wave movement Example – ocean waves Ocean waves animation Surface Waves

  7. Ocean Waves Near Shore • Wave simulation

  8. Period (T) Frequency (ƒ) Wavelength (λ) Speed (v) Amplitude Properties of waves video clip Properties of Waves

  9. Period (T) - time required to go through one cycle. Measured in seconds Frequency (ƒ)- number of cycles in a certain time. ƒ=1/T measured in s-1 or Hz HERTZ, one Hz Period and Frequency

  10. Wavelength (λ)- distance between two identical points on consecutive waves measured in meters (or km, cm, etc) Increasing the frequency of a wave decreases its wavelength. Wavelength

  11. Speed • Speed (v) - how fast the wave is moving • v=λƒ • measured in m/s (or km/s, cm/s, etc)

  12. Amplitude • Amplitude - max displacement from its rest position (also known as wave height) • measured in meters (or km, cm, etc) • Example – dropping a pebble in the water vs. doing a “cannonball” jump into the water • VERY IMPORTANT: The more energy a wave has, the greater is its amplitude!!!

  13. Classwork/Homework • p. 503) 1-7 • p. 507) 2, 3, 8-10 • p. 527) 1-6, 13-15, 30-33 • Study the Chapt 17!

  14. Warm-up • Did you do these? • p. 503) 1-7 • p. 507) 2, 3, 8-10 • p. 527) 1-6, 13-15, 30-33 • Study your notes! You have a Quiz on Waves!!!

  15. Speed Frequency & Wavelength Speed S = x f = 1.5 m x 280 Hz = 420 m/s Wavelength x frequency S = S / f = 5.0 m/s / 2.5 Hz = 2 m x f • Speed (meters/sec)= wavelength x frequency • Frequency (Hz = 1/sec)= speed / Wavelength • Wavelength (meters) = speed / Frequency • Designated by Greek letter lambda -

  16. p.506 intextbook Speed Wavelength x frequency

  17. Reflection is when waves, whether physical or electromagnetic, bounce from a surface back toward the source. Ex - a mirror reflects the image of the observer. Refraction is when waves, whether physical or electromagnetic, are deflected when the waves go through a substance. The wave generally changes the angle of its general direction. Diffraction is the bending of a wave as it moves around an obstacle or passes through a narrow opening. Interactions of Waves

  18. Interference- when two waves collide • Constructive Interference – the combining of waves to cause higher amplitude of any of the original waves. • Destructive Interference – when the combining of the waves produce a new wave with a smaller amplitude than the beginning waves

  19. appear to stay in one place result of constructive and destructive interference between original wave and reflected wave contains node(s) and antinode(s) Forms only if half a wavelength or a multiple of it fits exactly into the length of the rope Standing Waves

  20. Sound and Hearing 17-4

  21. Properties of Sound Waves • Longitudinal waves • speed- travels at different speeds in different media • air- 343m/s fresh water- 1510m/s Salt water- 1550m/s • Aluminum- 5000m/s • Intensity- rate at which a wave's energy flows through an area • measured in Decibels, dB • Loudness- physical response to sound • Pitch- frequency of sound as you hear it. Higher frequency, higher note • Infrasound and Ultra sound

  22. The Doppler Effect • Change in frequency due to motion of source, listener, or both • Ex: When a vehicle sounding a siren or horn approaches, passes, and recedes from an observer.

  23. Basically the object goes faster than the speed of sound http://www.kettering.edu/~drussell/Demos/doppler/doppler.html Sonic boom explained Sonic Boom- breaking of sound barrier

  24. Outer Ear- gathers and focuses sound into middle ear Middle Ear- receives and amplifies vibrations Inner Ear- uses nerve endings to sense vibrations Hammer, anvil, cochlea Hearing and our Ears

  25. Instruments • alter pitch by changing frequency of standing waves • change tension, length, and amplitude • Resonance- increased amplitude over time because of added energy. • Resonance animation

  26. Video Clip • Sonic Boom • Sonic boom explained • Deadliest catch – monster waves • World’s Biggest Wave ever surfed

  27. Go over QS !! • p. 503) 1-7 • p. 507) 2, 3, 8-9 • p. 527) 1-6, 13-15, 30-33

  28. Wrap-up What is the Doppler effect? What is a sonic boom?

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