Chapter 11-12 Review

1. Chapter 11-12 Review

2. Ch. 11 page 396-3981, 4, 7, 8, 12, 14, 16, 19, 21, 23-25, 31, 32, 35, 37, 41, 42 • 1. Oscillation about an equilibrium position in which a restoring force is proportional to displacement. • 4. No. A pendulum’s displacement is approximately proportional to its restoring force only at angles smaller than 15 degrees. • 7. The tangent component (Fgx); because it always pulls the bob toward the equilibrium position • 8. see solution page

3. Ch. 11 page 396-3981, 4, 7, 8, 12, 14, 16, 19, 21, 23-25, 31, 32, 35, 37, 41, 42 • 12. The period and frequency are inversely related. • 14. There would be no change in frequency or period because the frequency or period does not depend on the pendulum’s mass. • 16. If it is running slow, make the pendulum length longer. • 19. see solution page • 21. see solution page

4. Ch. 11 page 396-3981, 4, 7, 8, 12, 14, 16, 19, 21, 23-25, 31, 32, 35, 37, 41, 42 • 23. For a transverse wave, the vibration direction is perpendicular to wave travel. For a longitudinal wave, the vibration direction is parallel or in the same direction as wave travel. • 24. a the particles are moving up and down b) the wave is transverse • 25. This is a longitudinal wave (compressions and rarefactions) • 31. Sound waves are mechanical waves, which are produced by the displacement of particles. Without matter, no propagation of wave energy occurs.

5. Ch. 11 page 396-3981, 4, 7, 8, 12, 14, 16, 19, 21, 23-25, 31, 32, 35, 37, 41, 42 • 32. Neither. Wave speed depends only upon the medium which is travels through (solid, liquid, gas or vacuum) • 35. see solutions page • 37. In constructive interference, individual displacements are on the same side of the equilibrium position. In destructive interference, the individual displacements are on opposite sides of the equilibrium position. • 41. The resultant displacement is zero (totally cancels at that position) • 42. Yes. When interference is constructive.

6. Ch. 11 page 400--401 STP (1-5, 7-18). 10. H (see solution page) 11. A 12. H 13. A 14. J [ .75 m + .53 m] 15. A [.75 m - .53 m] 16. G (see solution page) 17. (see solution page) 18. electromagnetic waves • 1. C • 2. J (see solution page) • 3. C • 4. F • 5. C • 7. B • 8. G • 9. A [12 cycles/120 sec]

7. Ch. 12 page 434-435 3, 4-6, 8, 9, 11, 13, 16, 18, 22, 23, 25, 27, 38, 40a • 3. Frequency measure of the rate of particle vibrations (# of vibrations per second is Hz). Pitch is the frequency of a sound wave as experienced by the listener. • 4. infrasonic is less than 20 Hz, audible is between 20-20,000 Hz, and ultrasonic is above 20,000 Hz. • 5. The speed of any wave changes as the medium changes. A temperature increase makes the air molecules move faster, so it is easier to transfer sound waves. • 6. You know when the ambulance passes when you hear the pitch of the siren drop from higher to lower. • 8. If wavelength decreases by 2 times, then the frequency will increase by 2 times (inverse relationship). Since wave speed depends only on the medium, there is no change in wave speed unless the medium changes.

8. Ch. 12 page 434-435 3, 4-6, 8, 9, 11, 13, 16, 18, 22, 23, 25, 27, 38, 40a • 9. Sound waves (or mechanical waves) travel faster through solids than through gases. • 11. The driver of the van in front of the ambulance, because the source of the waves (siren) is approaching the observer. • 13. Intensity is the measure of power per unit area (W/m2). Decibel level is related to how we perceive loudness (dBs), which is relative intensity. • 16. Resonance occurs when the forced vibration matches the natural frequency (or frequencies) of a substance or vibrating system. • 18. 10 dB difference means 10 times louder; so nine machines could be added (10 units = 10 dB increase)

9. Ch. 12 page 434-436 3, 4-6, 8, 9, 11, 13, 16, 18, 22, 23, 25, 27, 38, 40a • 22. see solution page • 23. see solution page • 25. L = 2.0 m, so a) 4.0 m (2L) b) 2.0 m (L) c) 1.3 m (2/3L) d) 1.0 m (1/2L) • 27. The two different instruments have different harmonics present at different intensities. • 38. see solution page • 40a see solution page

10. Ch. 12 page 438-439 STP (1-11, 14, 17-19) 9. D 10. G (see solution page) 11. 7 beats per second 14. see solution page 17. see solution page 18. see solution page 19. see solution page • 1. B • 2. J • 3. D • 4. H (103 is 30 dB increase) • 5. C • 6. F • 7. B • 8. G (see solution page)