lecture 6- standing waves chapter 16jn511/lectures/lecture6slides.pdf · lecture 6- standing waves...

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Lecture 6- Standing WavesChapter 16

Prof. Noronha-HostlerPHY-124H HONORS ANALYTICAL PHYSICS IB

Phys- 124HFeb. 22nd , 2018

Recall the velocity of a string

Infinitesimal String

Two Waves

Superposition

Phasar

Resonance

16.4.1. Jimmy and Jenny are floating on a quiet river using giant doughnut-shaped tubes. At one point, they are 5.0 m apart when a speed boat passes. After the boat passes, they begin bobbing up and down at a frequency of 0.25 Hz. Just as Jenny reaches her highest level, Jimmy is at his lowest level. As it happens, Jenny and Jimmy are always within one wavelength. What is the speed of these waves?

a) 1.3 m/s

b) 2.5 m/s

c) 3.8 m/s

d) 5.0 m/s

e) 7.5 m/s

16.4.1. Jimmy and Jenny are floating on a quiet river using giant doughnut-shaped tubes. At one point, they are 5.0 m apart when a speed boat passes. After the boat passes, they begin bobbing up and down at a frequency of 0.25 Hz. Just as Jenny reaches her highest level, Jimmy is at his lowest level. As it happens, Jenny and Jimmy are always within one wavelength. What is the speed of these waves?

a) 1.3 m/s

b) 2.5 m/s

c) 3.8 m/s

d) 5.0 m/s

e) 7.5 m/s

16.4.2. The drawing shows the vertical position of points along a string versus distance as a wave travels along the string. Six points on the wave are labeled A, B, C, D, E, and F. Between which two points is the length of the segment equal to one wavelength?

a) A to E

b) B to D

c) A to C

d) A to F

e) C to F

16.4.2. The drawing shows the vertical position of points along a string versus distance as a wave travels along the string. Six points on the wave are labeled A, B, C, D, E, and F. Between which two points is the length of the segment equal to one wavelength?

a) A to E

b) B to D

c) A to C

d) A to F

e) C to F

16.5.2. The equation for a certain wave is y = 4.0 sin [2(2.5t + 0.14x)] where y and x are measured in meters and t is measured in seconds. What is the magnitude and direction of the velocity of this wave?

a) 1.8 m/s in the +x direction

b) 1.8 m/s in the x direction

c) 18 m/s in the x direction

d) 7.2 m/s in the +x direction

e) 0.35 m/s in the x direction

16.5.2. The equation for a certain wave is y = 4.0 sin [2(2.5t + 0.14x)] where y and x are measured in meters and t is measured in seconds. What is the magnitude and direction of the velocity of this wave?

a) 1.8 m/s in the +x direction

b) 1.8 m/s in the x direction

c) 18 m/s in the x direction

d) 7.2 m/s in the +x direction

e) 0.35 m/s in the x direction

16.6.1. The tension of a guitar string in increased by a factor of 4. How does the speed of a wave on the string increase, if at all?

a) The speed of a wave is reduced to one-fourth the value it had before the increase in tension.

b) The speed of a wave is reduced to one-half the value it had before the increase in tension.

c) The speed of a wave remains the same as before the increase in tension.

d) The speed of a wave is increased to two times the value it had before the increase in tension.

e) The speed of a wave is increased to four times the value it had before the increase in tension.

16.6.1. The tension of a guitar string in increased by a factor of 4. How does the speed of a wave on the string increase, if at all?

a) The speed of a wave is reduced to one-fourth the value it had before the increase in tension.

b) The speed of a wave is reduced to one-half the value it had before the increase in tension.

c) The speed of a wave remains the same as before the increase in tension.

d) The speed of a wave is increased to two times the value it had before the increase in tension.

e) The speed of a wave is increased to four times the value it had before the increase in tension.

16.7.2. During a rock concert, the lead guitarist plucks the high E (329.6 Hz) string, which has a mass of 0.208 g and a length of 0.628 m. The tension on the string is 226 N. If the amplitude of the wave on the string is 3.0 mm, what is the average rate of energy transport on the string?

a) 2130 W

b) 1760 W

c) 975 W

d) 547 W

e) 122 W

16.7.2. During a rock concert, the lead guitarist plucks the high E (329.6 Hz) string, which has a mass of 0.208 g and a length of 0.628 m. The tension on the string is 226 N. If the amplitude of the wave on the string is 3.0 mm, what is the average rate of energy transport on the string?

a) 2130 W

b) 1760 W

c) 975 W

d) 547 W

e) 122 W

16.10.1. Which one of the following waves would undergo fully destructive interference with a wave described by y = 2.0 sin (3.0x 0.5t) where y and x are measured in meters and t is measured in seconds?

a) y = 2.0 sin (3.0x 0.5t)

b) y = 2.0 sin (3.0x + 0.5t))

c) y = 2.0 sin (3.0x 0.5t))

d) y = 2.0 sin (0.33x 2.0t)

e) None of these equations will fully interfere destructively with the given wave.

16.10.1. Which one of the following waves would undergo fully destructive interference with a wave described by y = 2.0 sin (3.0x 0.5t) where y and x are measured in meters and t is measured in seconds?

a) y = 2.0 sin (3.0x 0.5t)

b) y = 2.0 sin (3.0x + 0.5t))

c) y = 2.0 sin (3.0x 0.5t))

d) y = 2.0 sin (0.33x 2.0t)

e) None of these equations will fully interfere destructively with the given wave.

16.13.1. Which one of the following statements explains why a piano and a guitar playing the same musical note sound different?

a) The fundamental frequency is different for each instrument.

b) The two instruments have the same fundamental frequency, but different harmonic frequencies.

c) The two instruments have the same harmonic frequencies, but different fundamental frequencies.

d) The two instruments have the same fundamental frequency and the same harmonic frequencies, but the amounts of each of the harmonics is different for the two instruments..