D. The Speed of any Wave The speed v of a wave depends on…

1. D. The Speed of any Wave The speed v of a wave depends on… 1/ ….what __________________ it travels through. E.g., air vs. water vs. glass vs. earth vs. etc…. …or the __________ of a medium (a _____________) 2/ ….the ______________________ of that medium. E.g., temp. vs. pressure vs. "elastic-ness" vs. density 3/ …but NOT on the __________________ of the wave. medium vacuum lack properties amplitude A same speed

2. Ex. sound Sound is a ____________________ wave. It is transmitted by the _____________ of atoms or by the _______________ of particles that are bonded to each other. The atoms exchange ______ (motion) or ________ (bonding). mechanical collisions vibrations PE KE collisions (in gases and liquids): atom atom atom atom vibrations (in solids): atom atom atom atom bond bond bond bond bond

3. As air is evacuated, the sound ceases to be heard. no medium…. …no sound

4. Sound waves are _______________________ : longitudinal tines compression rarefaction tuning fork

5. sound The speed of __________ waves in different media: 331 (~700 mph) in air: __________ m/s at STP Sound travels ________________ at higher air temps because ______________________________________. faster the air molecules are moving faster 1500 m/s in water: ____________ increasing _________ density 6000 m/s (~13,000 mph)! in steel: ____________ faster Mechanical waves such as sound travel ___________ in _________ media because __________________________ ___________________________________________________ . the molecules are closer, denser and that helps to pass the wave faster Unless a wave enters a new _______________ , or the medium _______________ , the wave speed will be _______________ , and its acceleration is __________ . medium changes 0 constant

6. Reference Tables page 1:

7. E Ex. light v B Light is a ____________________________________ wave.  It requires __________________________. transverse electromagnetic no medium light The speed of __________ waves in different media: 2.998 x 108 in vacuum: _______________ m/s c This speed is given the symbol ______.

9. 3.00 x 108 m/s in air: _________________ increasing _________ 2.0 x 108 m/s in water: _________________ density 1.5 x 108 m/s in glass: _________________ Electromagnetic waves such as light travel __________ ___________ in denser media because the light must be _____________ by one atom and then has to be _____________ by the same atom before moving on to the next atom. This process _________________ the overall speed. In between atoms, the light travels at ______ . more slowly absorbed emitted slows down atom = __________ c light = __________ stops slower higher _________ density  more _________  ___________ speed

11. Earthquake waves: P waves: -longitudinal -travel thru solid and liquid S waves: -transverse -travel thru solid only compression can propagate as a wave in liquids P wave v sideways motion does not propagate as a wave in liquids S wave v

12. 3 2 1 Finding an Equation for the Speed of a Wave. Three train cars pass a point in one second. If each car is 10 m long, how fast is the train moving? v = = (3 cars/second) x (each car is 10 m long) 30 m/s Instead of cars, think: waves frequency v = x wavelength v = fl

13. From the Reference Tables:

14. 1 T Because f = v = fl can be written: v = Compare this to v = Conclusion: One __________________ is the distance that a wave travels in a time of one __________________ . Stated another way: One ______________ is the time it takes a wave to travel a distance of one ___________________ . l T d t wavelength period period wavelength wave The wave travels this far in a time ______ l T

15. Ex: Find the speed of a water wave that has a wavelength of 5.5 meters and a frequency of 2.8 Hz. Given: v = fl l = (5.5 m) v = (2.8 Hz) (5.5 m) f = (2.8 Hz) v = (15 m/s) v = ? How long with it take this wave to travel a mile (1610 m)? v = d/t v = 15 m/s Given: 15 m/s (1610 m)/ = t d = 1610 m t = 110 s t = ?

16. air The speed of sound waves in _____ and of light waves in a __________ (and in air for the most part) is _______________ of the frequency. Then v is ___________ , and v = fl means: vacuum independent constant l fl v = high short  ________ f  _______ l fl l v = low long  ________ f  _______ l As long as the speed is ____________, there is ______________relationship between the ________________ and the _______________________ . constant f an inverse frequency wavelength l

17. pitch Sound: Frequency determines ______________ low f: ________   high f: _________ Light: Frequency determines ________________ low f: ________   high f: _________ treble bass color blue red Wavelength: ___________ ____________ Frequency: ___________ ____________ Sound: ___________ ____________ Light: ___________ ____________ long short high low bass treble redder bluer

18. Humans can hear frequencies in the range: 16Hz-16kHz l~5 mm l~2 m l~20 cm l~5 cm

19. Visible light is only a _______ fraction of the E&M spectrum. tiny 2 Reference Tables: page _______: ________ wavelength short long ________ wavelength low ________ frequency high ________ frequency __________ light only ____________Hz visible 3-8 x 1014

20. high f low f

22. Why are radio telescopes so big??? Arecibo, Puerto Rico 1000 ft

23. Green Banks, West Virginia Why don’t radio telescopes have shiny surfaces?

24. Ex: Radio waves and light are types of ___________________ radiation. One way that information can be sent by radio waves is by _____________________ (changing) the wave's ___________________ : This is called FM. Here is how it is done: electromagnetic modulating frequency 1. This wave has the ___________________ info to be sent 2. This wave is called the ____________ carrier FM wave 3. This is the ___________ The ____________ wave's frequency has been ______________ by wave 1. carrier modulated

25. Do not confuse radio waves sent as ___________________ waves with sound waves, which are ___________________ waves. electromagnetic mechanical antenna or satellite transmits ________ waves antenna E&M A radio or computer receives ______________ waves. It then converts them into________________ signals, which it sends to a speaker. The speaker turns them into _______________________waves, which you can hear. the E&M electrical mechanical sound antenna sound E&M electrical ________ energy  ___________energy  ________ energy

26. Ex. String (or wind) instruments are played by making the string (or tube) _____________________________ . longer or shorter v = fl constant v is _________________ for a fixed tension. Shorter string  l _____________  f ___________ shorter increases l/2 L = _______ v = fl vibrating string Now shorten the string or tube: fl v = shorter L is ___________ , so l is ____________ . higher shorter  ___________ f

27. Ex. strings or wires tension v ~ T (m/L) mass per unit length waves travel on the strings increases Increasing T or using thinner wires ____________v. v = fl: For a fixed string length (a fixed l), if v is _____________ , f will ________________. increased increase