Chapter 11-12 Review

Ch. 11 page 396-398
1, 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 (F gx ); because it always pulls the bob toward the equilibrium position
• 8. see solution page

Ch. 11 page 396-398
1, 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

Ch. 11 page 396-398
1, 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.

Ch. 11 page 396-398
1, 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.

Ch. 11 page 400--401 STP (1-5, 7-18).
• 1. C
• 2. J (see solution page)
• 3. C
• 4. F
• 5. C
• 7. B
• 8. G
• 9. A [12 cycles/120 sec]
• 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

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.

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/m 2 ). 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)

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

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