Physics Review - WAVES I. MATCHING: __i_ 1. the low point of a transverse wave __a_ 2. distance from the top of a crest to the equilibrium position __c_ 3. waves that can travel through empty space __e_ 4. unit for measuring frequency __m_ 5. a traveling wave which causes matter to move at right angles to the direction of the wave __l_ 6. the distance a wave travels during one complete vibration __b_ 7. a wave that causes matter to move back and forth parallel to the direction of the wave __g_ 8. the bouncing back of a wave from a surface __d_ 9. the number of waves that pass a certain point each second __f_ 10. the result of waves moving through each other __k_ 11. the time is takes for one complete vibration __h_ 12. the material through which a wave travels a. amplitude b. longitudinal c. electromagnetic d. frequency e. hertz f. interference g. reflection h. medium i. trough j. compression k. period l. wavelength m. transverse II. FILL IN THE BLANK: 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. A wave transfers ____energy_____ from one place to another. A wave with a great amount of energy has a large _____amplitude __________. Two waves travel through the same medium. They must have the same __velocity____. If the wavelength of a wave “A” is four times that of wave “B”, then the frequency of “A” is ___1/4___ that of “B”. Surface water waves are (transverse, longitudinal) and (electromagnetic, mechanical). Radio waves are (electromagnetic, mechanical) because they do not need a medium. Refraction occurs because the new medium changes the wave’s velocity. The angles at which a wave hits and reflects from a boundary are always equal. Sound waves bend around a corner because their wavelength is large compared to the size of the opening. This spreading is called diffraction. In an interference pattern, points of total destructive interference are called nodes and points of total constructive interference are called antinodes. Damping is the decrease in the amplitude of the wave due to energy lost in overcoming friction and due to the spreading out of the wave front. The frequency of a pendulum is affected by its length, not by its mass or amplitude. Waves travel slower in shallow water than in deep. When waves enter the shallow water they refract, or bend (away from, toward) the normal line drawn between the two levels of water. You stand in the back left corner of a racquetball court and hit the ball to the middle of the front wall. Your opponent should stand in the back right corner to return the ball. Teacher Copy Unit 11 All Rights Reserved, GPTC 2003 34 14. 15. 16. Waves reflected from a flexible boundary are (erect, inverted). When a wave reaches a new medium which is very different from the old, most of the wave will be reflected and a little will be transmitted. When a wave passes into a new medium, its (f, ,v) does not change, but its (f, ,v) and (f, ,v) do change. III. PROBLEMS: 1. The speed of sound in air is 346 m/s. A sound wave has a frequency of 750 Hz. What is its wavelength? λ= v 346 = f 750 T= 1 1 = f 750 m s 1 s = 0.46 m What is its period? 2. 1 s = 0.0013 s It is observed that 15 waves hit the shore every 10 minutes. The distance between successive crests is 3.2 m. a. What is the frequency of the waves in Hz? f= 15 waves = 0.025 Hz 10 min × 1 60mins b. What is the velocity of the waves? v = fλ = 0.025 3. 1 s × 3.2 m = 0.080 m s In figure A, draw the reflected wave, label angles, and draw wave fronts. In figure B, draw the refracted waves, label angles, and draw wave fronts. A. B. B. fast r i N i r N slow Teacher Copy Unit 11 All Rights Reserved, GPTC 2003 35