21 homework RAHMAN, TARIQUE Due: Apr 21 2008, 3:00 am 4. The lower strings are plucked by a ghost. Question 1, chap 15, sect 4. part 1 of 2 10 points Question 4, chap 15, sect 5. part 1 of 1 10 points
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If the handle of a tuning fork is held solidly against a table, the sound from the tuning fork becomes louder. Why? How will this aect the length of time the fork keeps vibrating? Explain. 1. Beacuse a greater surface is set into vibration, the sound becomes louder. In keeping with the conservation of energy, this reduces the length of time the fork keeps vibrating. 2. Because a more massive surface is set into vibration, the sound becomes louder and the length of the fork keeps vibrating becomes longer. 3. Because a more massive surface is set into more lower frequency vibration, the sound becomes louder. In keeping with the conservation of energy, this reduces the length of time the fork keeps vibrating. 4. Because a greater surface is set into vibration, the sound becomes louder. In keeping with the conservation of momentum, this reduces the length of time the fork keeps vibrating. Question 5, chap 16, sect 1. part 1 of 1 10 points Sound in air can best be described as which of the following type of wave? 1. Longitudinal 2. Polarized 3. Transverse 4. Torsional 5. Electromagnetic
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A simple pendulum has a period of 5.5 s. The acceleration of gravity is 9.8 m/s2 . What is its length? Answer in units of m. Question 2, chap 15, sect 4. part 2 of 2 10 points What would its period be on the Moon, where its gravity is 1.67 m/s2 ? Answer in units of s. Question 3, chap 15, sect 5. part 1 of 1 10 points The sitar, an Indian musical instrument, has a set of strings that vibrate and produce music, even though they are never plucked by the player. These sympathetic strings are identical to the plucked strings and are mounted below them. What is your explanation? 1. Scientists are still studying to nd the reason. 2. The upper strings are to connected the lower strings with invisible strings. 3. The lower strings are resonating with the upper.
homework 21 RAHMAN, TARIQUE Due: Apr 21 2008, 3:00 am Question 6, chap 16, sect 1. part 1 of 1 10 points As your hand moves back and forth to generate longitudinal pulses in a spiral spring, your hand completes 2.89 back-and-forth cycles every 7.72 s. The velocity of the pulse in the spring is 0.604 cm/s. What is the wavelength? Answer in units of m. Question 7, chap 16, sect 2. part 1 of 1 10 points Two harmonic waves are described by y1 = A sin(k x + t) y2 = A sin(k x t) , where A = 3 m, k = 2 m , and = 4 s . What is the maximum amplitude of the resultant waves at the position of 5.5 m along the x-axis? Answer in units of m. Question 8, chap 16, sect 2. part 1 of 1 10 points Explain how you can lower the pitch of a guitar string by altering (a) the length of the string, (b) the tension of the string, or (c) the thickness of the string. 1. By making a string (a) longer, (b) looser, and (c) more massive. 2. By making a string (a) shorter, (b) tighter, and (c) lighter. 3. By making a string (a) longer, (b) looser, and (c) lighter. 4. By making a string (a) shorter, (b) looser, and (c) more massive. 5. By making a string (a) longer, (b) tighter, and (c) more massive. Question 9, chap 16, sect 2. part 1 of 1 10 points
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A harmonic longitudinal wave propagating down a tube lled with a compressible gas has the form s(x, t) = sm cos(kx t). Its velocity can be obtained from 1. 2. k 3. /k 4. k/ 5. k Question 10, chap 15, sect 5. part 1 of 3 10 points A 0.2 kg object oscillates with an initial amplitude of 780 cm on a spring of force constant 807.4 N/m. Find the period. Answer in units of s. Question 11, chap 15, sect 5. part 2 of 3 10 points Find the total initial energy. Answer in units of J. Question 12, chap 15, sect 5. part 3 of 3 10 points If the energy decreases by 1 percent per period, nd the damping constant b. Answer in units of kg/s.