Wave Basics

Wave Basics Name: Waves the Waves chapter at The Physics Classroom: http://www.physicsclassroom.com /Class/waves/ ulOlla.html http://www.physicsclassroom.com /Class/waves/ ulOllb.html http://www.physicsclassroom.com /Class/waves/ ulOllc.html Read from Lesson 1 MOP Connection: Waves: sublevel 1 TRUE or FALSE: Identify the following statements as being either true (T) or false ( F). T o r F? 1. Waves are created by a vibration. r 2. ± 3. r 4. 5. 6. Describe how a wave is different than a pulse. PiUc IAJ Av t- 7. 8. As a wave moves through a medium, the individual particles of the medium move from the source of the wave to another location some distance away. Waves are a means of transporting energy from one location to another without actually displacing matter from one location to another. An ocean wave will transport ocean water from near the middle of the ocean to a location near the shore. As mechanical waves move through a medium, particles of the medium undergo a periodic and repeated vibration about a fixed position. - O ( . Mechanical waves propagate or move through a medium because a. the particles of the medium are able to move along the curved wavelike pathway /5) one particle pushes or pulls on the adjacent particle which pushes or pulls on the next particle which ... c. the initial vibration of the medium causes the medium to assume the wavelike shape and this shape subsequently moves from one location to another. Which of the following categories of waves require a medium in order to transport energy from one cation to another ? 1 mechanical b. electromagnetic Q © The Physics Classroom, 2009 Page 1 Wave Basics 9. What's Wrong With This? involves a spaceship Suppose you're watching a science fiction movie and one of the scenes B . The scene is on spaceship strike battle in outer space. Spaceship A launches a successful view A of spaceship presented from the perspective of spaceship A. The occupants flames of the see spaceship B blowing up as the result of the successful missile strike. They . the explosion and shortly thereafter hear the thunderous sound of the explosion While the scene is definitely exciting, there is a significant fault with it in terms of the physics. What law of physics was violated in the filming of the scene? Explain. — _ Y \ C> VScAe 5 1 \ t \ S° ' " v ( ho / A 10. The arrows on the diagrams below represent the direction of particle motion. Diagram A Diagram B 11. Compare the direction in which particles of the medium vibrate for a longitudinal 4, C v Dsq I ( ahr I wave compared to a transve -^5 \ ju u\J t \ ( iu\ CAJ OS CA Iro - o 5c t / 1^ 3 4-o / Name: Wave Basics Describing Waves Read from Lesson 2 of the Waves chapter at The Physics Classroom: http:// www.physicsclassroom .com/Class/ waves/ul0l 2a .html http:/ /www.physicsclassroom.com/Class/ waves/ ulOl 2b.html http:// www.physicsclassroom.com/Class/ waves/ ulOl 2c.html http://www.physicsclassroom.com/Class/waves/ul0l2d.html MOP Connection: 1. Waves: sublevels 2 and 3 A wave is introduced into a medium and a snapshot of the medium at a particular instant in time is shown at the y right. Several positions along the medium are labeled. Categorize the positions as either crests or troughs. f7 C Troughs: Crests: fb j B E ^ ^ ^ H D (P (\ Neither: 0 r ) J G 1 f ~ The wavelength of the wave in the diagram below is given by letter * wave in the diagram below is given by letter T) 2. I F C A ; £ ( ft ( -L j J and the amplitude of the — — •4 E A sine curve that represents a transverse wave is drawn below. Use the centimeter ruler to measure the wavelength and amplitude of the wave (show units). 3. O 1111111 111111111 111111111111111 111111111 i 3 2 i o 1 llll 111111111 |M 1111111111111111111111111111111111111111111111111111111111111111111111111 5 6 7 8 b. Amplitude = Z a. Wavelength = i 10 9 6 11 12 13 14 , The number of cydes of a periodic wave per unit time is called the wave 's Any repeated and periodic motion can be described by a frequency. For instance, the frequency of rotation of a second hand on a dock is d. 1 Hz e. 60 Hz c. 1 / 2 Hz b. 1 / 12 Hz a. 1/ 60 Hz 4. 5. 6. A pendulum makes 40 vibrations in 20 seconds. Calculate its period ? 2 iie. . I x> *2 T- " Hi Throughout this unit, internalize the meaning of terms such as period, frequency, wavelength and speed. Utilize the meaning of these terms to answer conceptual questions; avoid formula fixation. 2- 5 © The Physics Classroom, 2009 Page 3 Wave Basics 7. of fun. hilethere, Olive Udadi accompanies her father to the park for an afternoon forth cy ry . and swing and begins a motion characterized by a complete back' statement provides info about the child s C, c. period b. frequency a. speed ^ 8. The frequency of Olive's periodic motion (in # 7) is R, yd. 5.0 Hz c. 2.5 Hz b. 0.40 Hz a. 0.20 Hz 9. A period of 5.0 seconds corresponds to a frequency of Qo Hz. c. 0.02 b. 0.5 a. 0.2 10. The period of a 261-Hertz sound wave is 0 ,0 0 3 7 5 e. 0.002 d. 0.05 . 11. As the frequency of a wave increases, the period of the wave decreases c. remains the same b. increases ^ 12. The speed of a wave refers to a. how often it vibrates to and fro. b. how high it vibrates. c. how much time it takes to vibrate to and fro. 5. how far a given point (e.g., a crest) on the wave travels per unit of time. £ 13. Write the two equations that can be used to determine the speed of a wave. L < — \j t 14. Mac and Tosh are resting on top of the water near the end of the pool when Mac creates a surface wave. The wave travels the length of the pool and back in 25 seconds. The pool is 25 meters long. Determine the speed of the wave. PSYW [<2 d’ ^ c2 0 rv\ ^ _ c 5o ^ ^ 15. A fisherman uses a sonic ranger to determine the depth of a lake. The sound waves travel at 1210 m / s through the water and require 0.020 seconds to travel to the lake's bottom and back to the boat. How deep is the lake? PSYW . 2- ^ r dcA^-’ w t T " O.Ols O -3- ' 0.02- r " 2 . 2- OA 16. The water waves below are traveling with a speed of 3.0 m / s and splashing periodically against the cL - V ^ perch. Each adjacent crest is 6.0 meters apart and splashes Wilbert 's feet upon reaching his perch. How much time passes between each successive drenching? Answer and Wilbert 's explain using complete sentences or a calculation. K 6.0 m >1 V =3 .fl m/s a-G * 3 VM m Co © The Physics Classroom, 2009 ^ ^ 22 2^ Page 4 5 f Wave Basics Name: Wave Speed Read from Lesson 2 of the Waves chapter at The Physics Classroom: http://www.physicsclassroom.com/Class/waves/ul 0l2d.html http:/ / www . physicsclassroom.com/Class/ waves/ul 0l 2e.html MOP Connection: Waves: sublevels 3 and 4 y t the Wal1 and be introducing pulses with different bfrv,atof the twoSHnlf lSSetew ahS e. Which mplitud pulses below will take the least amount of time to reach the L 3 §ins 0 wall ? WawteA Justify your answer: I 2. S' 2 ^ wavelength Which \/ JLA O CA The physics teacher then begins introducing pulses with a different pulses below will take the least amount of time to reach the wall ? TT ) . of the two Wave C Justify your answer: 5^-^—^— 3. 1 "S So the possible effect of several Stan and Anna are conducting a slinky experiment. They are studying below. Fill in the blanks in shown is table data Their . variables upon the speed of a wave in a slinky . s g question followin the answer the table, analyze the data, and Speed Frequency Wavelength Medium 2.0 Hz 1.75 m Zinc, 1-in. dia. coils 3.9 Hz > 0.90 m Zinc, 1-in. dia. coils 2.1 Hz 1.19 m -5 Copper, 1-in. dia. coils 2 .S l g Copper, 1-in. dia . coils 0.60 m 4.2 Hz Zinc, 3-in. dia. coils 1.82 m 2.2 Hz Zinc, 3-in . dia. coils 0.95 m 4.2 Hz © The Physics Classroom, 2009 »-S Page 5 1 \ Wave Basics will As the wavelength of a wave in a uniform medium mgseases, its speed same 'S / CyTemain the b. increase a. decrease the wavelength of a wave in a uniform medium increases, its frequency will 5 c. remain the same b. increase decrease 6. The speed of a wave depends upon (i.e., is causally effected by) ... ( ) the properties of the medium through which the wave travels c. the frequency of the wave b. the wavelength of the wave. wave. the of d. both the wavelength and the frequency 4. & ^ i 7. , 13 A water gun fires 5 squirts per second. The speed of the squirts is 15 m / s. • 0 o By how much distance is each consecutive squirt separated ? a. + 5 v svti y c 3^- \ A b. What happens to the distance between the squirts if the rate of fire is increased ? c. Explain how this example is analogous to the relationship between wave frequency and wavelength. (AJ~> 'tfKc- V' JLtK ’SA S S > I 4 3 8. What is the speed of a wave that has a frequency of 200 Hz and a wavelength of 0.50 m ? PSYW \J 9. - If is 5 ^ \Q ^ 0 /5- ^ * /V\ _ 5 Waves are observed to splash upon the rocks at the shore every 6.0 seconds. The distance measured from crest to adjacent crest is 8.0 m . The distance measured from the lowest to the highest point on the medium is 10.0 m. nd speed ofihese Determine the frequency, w waves. PSYW JL io Do you have formula fixation? A useful test: were you successful with questions #8-11? - CAUTION! 10. The period of a wave is 0.0300 seconds. It travels at a velocity of 10.0 m / s. Determine the frequency -p- O, D S CO and the wavelength of the wave. PSYW 5 V) * 11. v ^ U ^ itfs ’3 3 . 3 Hz ' X IOi b rt f A wave having a wavelength of 4.0 meters and an amplitude of 2.5 meters travels a distance of 24 meters in 8.0 seconds. Determine the frequency and the period of the wave. PSYW ~ 0 %\ T.s X C\ V) $ x - xf - f75T7 12. Two boats are anchored 7.0 meters apart . They bob up and down, returning to the same up position every 10.0 seconds. The boats rise a vertical distance of 7.0 meters between their lowest and their highest point. When one is up the other is down. There are never any wave crests between the boats. Determine the period, frequency, wavelength, amplitude and speed of the waves. PSYW ^ - X _ > - ?/ 2- ' ViiiE- A I . TC i c< © The Physics ClassrbtmtTZOOS'J Page 6 ' IT. A - X • tsws**' Wave Basics Name: Standing Wave Mathematics Read from Lesson 4 of the Waves chapter at The Physics Classroom: MOP Connection: http://www. physicsclassroom.com/Class/ waves/ul0l 4a.html http://www. physicsclassroom.com/Class/waves/ul0l4b.html http://www.physicsclassroom.com/Class/waves/ul 0l 4c.html http://www.physicsclassroom.com/Class/ waves/ul0l 4d.html http://www.physicsclassroom.com/Class/waves/ulOl4e.html Waves: sublevels 7 and 8 A standing wave pattern results in a string, rope or snakey as a result of the interaction between the waves introduced on one end with the reflection of the waves returning from the opposite end. At certain frequencies, a pattern will be established within the medium in which there are positions that always appear to be stationary. Midway between each of these stationary positions are positions which are undergoing rapid motion between a maximum positive and maximum negative displacement from their resting position. , They 1. The positions along the medium that appear to be stationary are known as are points of no displacement. 2. The positions along the medium that are undergoing rapid motion between a maximum positive and maximum negative displacement are known as • They are the ft opposite of the points of no displacement. Label the nodes ( N) and antinodes (AN ) in the following standing wave patterns. ^ 3. PV s 3 KS od^S *? 4. In each of the two diagrams of standing wave patterns, count the number of nodes and antinodes. -S A -V v(^Q> * 5 6. wavelength. Each node is separated by the adjacent node by a distance that is equal to a. Draw the standing wave pattern that would result on the string below if the string vibrated with the first, second, and third harmonic wave patterns. State the relationship between length and wavelength for each of the three patterns. 1 st Harmonic 3 rd Harmonic 2 nd Harmonic * * 1 7. L = L = L = 4 A - the wavelength of the Suppose that the string in the above diagram is 1.2 meters long Determine . three patterns waves shown in each of these 3rd Harmonic 2nd Harmonic 1st Harmonic , -- ^ 1.2 5 X y 2 © The Physics Classroom, 2009 1 -7 ' 1 ^ . -iV i i ' Page 7 —- r Wave Basics 8. The string at the right is 1.5 meters long and is vibrating ^ vibrates up and down as the first harmonic. The string with 33 cycles in 10 seconds. Determine the frequency, period, wavelength and speed for this wave. PSAYW 1, 5 =5A 3 3c ^ cLey io > - 3^ T - b . Zs 3 ' 3Mz \/ ~ 9. The string at the right is 6.0 meters long and is vibrating as the third harmonic. The string vibrates up and down with 45 cycles in 10 seconds. Determine the frequency, period, wavelength and speed for this wave. PSAYW — I ^ X_ Lf S ^tA es (j ) >1 1.5 m k « i y £ V H cy \ & *5 ^ T ' \ ? X v iry b, 15 ^ ' 10. The string at the right is 5.0 meters long and is vibrating as the fourth harmonic. The string vibrates up and down with 48 cycles in 20 seconds. Determine the frequency, period, wavelength and speed for this wave. PSAYW -— X 5.0 m 3- y J2 0 i V ' l-W - S - " m Ml OT 11. The string at the right is 8.2 meters long and is vibrating as the fifth harmonic. The string vibrates up and down with 21 cydes in 5 seconds. Determine the frequency, period, wavelength and speed for this wave. PSAYW 8.2 m 3 .s A ' / The speed of the transmitted pulse will be speed of the incident pulse. The speed of the reflected pulse will be speed of the incident pulse. The wavelength of the transmitted pulse will be the wavelength of the incident pulse. © The Physics Classroom, 2009 ^ . JWV < ~ L- ^ eater tha ? less than, the same as) the (greater than, less than, thesameT$) the (We5Ferth5l>, less than, the same as) Page 11 VJ Wave Basics A pulse is moving from a less dense medium to a more dense medium as shown in the diagram below. medium 1 % ^4 MC rw o T 9. ^[ >_ > ^ ^^ ^ ^ (greater than,( ess h , the same as) the The speed of the transmitted pulse will be speed of the incident pulse. The speed of the reflected pulse will be speed of the incident pulse. 8. \ will not) be inverted because The reflected pulse in medium 2 7. (greater than, less than, t 10. the wavelength of the incident pulse. ) the same 11. Summarize your understanding of boundary behavior by completing the following statements. When a wave passes across the boundary from one medium to another medium, the ... ... speed is ((greater, smallest) in the least dense media . ({£reat0e$, smallest) in the least dense media. ... wavelength is (more ... the reflected pulse becomes inverted only when the inddent wave is in the ) . nmom, less dense medium dense medium and heading toward the ^ les ) ^ Express your understanding of the rules of boundary behavior by drawing the reflected and transmitted pulses in the following two situations. Show the orientation (inverted or non-inverted, wavelength and speed ) of each pulse. 12. Incident pulse is in the more dense medium and traveling toward the less dense medium. Boundaiy Boundary * —- : * : : : : -• - -> “S : : * > : : : — -—— > : - - -- - - J • ‘ J > • 0 • — > • C • 0 •• • — : - - > • ~0 • : i- 4. : : -. : -- - - - -> hddovt : • : “fr" 4 • *> • : : I- - > : : : : : -- • 0 •• -o : : : - 5 0 : -c- 5 • — > - - :- - - -- >• fr • 5 •• O ” —- -. - 5 •> •• fr •• O* •• —- - - 0 • 4 • . : >• - cj • T > : — : : : : > _ .. . j Transmitted Reflected 13. Incident pulse is in the less dense medium and traveling toward the more dense medium. Boundary Boundary d : : : : . : i : : : : : : : : : : : : : : : : : : : i...+ : : : : : : 4 : . : * : : : : z : z : - ~ • C • : 1 : : : — : : : : } • : : : : - - - -— : > ” i : : : : > <• > -:- 0 • : : : *A w i4 T “> • : : : y : i- —f--t f—t- — -t ' 0 4 hddent © The Physics Classroom, 2009 : : fr 0 « : -. a : : : : ! : Transmitted z : :« : : : f Reflected Page 12