Question 1

The speed of a 10-kHz sound wave in seawater is approximately 1 500 m/s.What is its wavelength in sea water?

Accepted Answer

A) 5.0 cm 
B) 10 cm 
C) 15 cm 
D) 20 cm 
E) 29 cm 
A) 5.0 cm 
B) 10 cm 
C) 15 cm 
D) 20 cm 
E) 29 cm

Question 2

Exhibit 16-2
The figure below shows a sine wave on a string at one instant of time.   Use this exhibit to answer the following question(s).
-Refer to Exhibit 16-2.Which of the graphs below shows a wave where the frequency and wave velocity are both doubled?

Accepted Answer

A)    
B)    
C)    
D)    
E)    
A)    
B)    
C)    
D)    
E)

Question 3

Calculate the displacement amplitude (in m)of a 20 kHz sound wave in helium if it has a pressure amplitude of 8.0 *10 - 3 N/m2.($\rho$ = 0.179 kg/m3,v = 972 m/s. )

Accepted Answer

A) 2.9 *10 - 10 
B) 3.7 *10 - 10 
C) 7.8 * 10 - 9 
D) 2.4 *10 - 9 
E) 1.9*10 - 10 
A) 2.9 *10 - 10 
B) 3.7 *10 - 10 
C) 7.8 * 10 - 9 
D) 2.4 *10 - 9 
E) 1.9*10 - 10

Question 4

When a workman strikes a steel pipeline with a hammer,he generates both longitudinal and transverse waves.The two types of reflected waves return 2.4 s apart.How far away is the reflection point? (For steel,vL = 6.2 km/s,vT = 3.2 km/s)

Accepted Answer

Question 5

To transmit four times as much energy per unit time along a string,you can

Accepted Answer

A) double the frequency. 
B) double the amplitude. 
C) increase the tension by a factor of 16. 
D) do any one of the above. 
E) do only (a)or (b)above. 
A) double the frequency. 
B) double the amplitude. 
C) increase the tension by a factor of 16. 
D) do any one of the above. 
E) do only (a)or (b)above.

Question 6

When you hear the horn of a car that is approaching you,the frequency that you hear is larger than that heard by a person in the car because for the sound you hear

Accepted Answer

A) wave crests are farther apart by the distance the car travels in one period. 
B) wave crests are closer together by the distance the car travels in one period. 
C) the car gets ahead of each wave crest before it emits the next one. 
D) the speed of sound in air is increased by the speed of the car. 
E) a speeding car emits more wavecrests in each period. 
A) wave crests are farther apart by the distance the car travels in one period. 
B) wave crests are closer together by the distance the car travels in one period. 
C) the car gets ahead of each wave crest before it emits the next one. 
D) the speed of sound in air is increased by the speed of the car. 
E) a speeding car emits more wavecrests in each period.

Question 7

A circus performer stretches a tightrope between two towers.He strikes one end of the rope and sends a wave along it toward the other tower.He notes that it takes 0.8 s for the wave to travel the 20 m to the opposite tower.If one meter of the rope has a mass of 0.35 kg,find the tension in the tightrope.

Accepted Answer

The answer of A circus performer stretches a tightrope between...

Question 8

A car moving at 36 m/s passes a stationary police car whose siren has a frequency of 500 hz.What is the change in the frequency (in Hz)heard by an observer in the moving car as he passes the police car? (The speed of sound in air is 343 m/s. )

Accepted Answer

A) 416 
B) 208 
C) 105 
D) 52 
E) 552 
A) 416 
B) 208 
C) 105 
D) 52 
E) 552

Question 9

Calculate the pressure amplitude (in N/m2)of a 500 Hz sound wave in helium if the displacement amplitude is equal to 5.0 *10 - 8 m.($\rho$ = 0.179 kg/m3,v = 972 m/s. )

Accepted Answer

A) 3.5 *10 1- 2 
B) 1.6 *10 - 2 
C) 2.7 *10 - 2 
D) 4.2 *10 - 2 
E) 2.0 *10 - 2 
A) 3.5 *10 1- 2 
B) 1.6 *10 - 2 
C) 2.7 *10 - 2 
D) 4.2 *10 - 2 
E) 2.0 *10 - 2

Question 10

A piano string of density 0.005 0 kg/m is under a tension of 1 350 N.Find the velocity with which a wave travels on the string.

Accepted Answer

A) 260 m/s 
B) 520 m/s 
C) 1 040 m/s 
D) 2 080 m/s 
E) 4 160 m/s 
A) 260 m/s 
B) 520 m/s 
C) 1 040 m/s 
D) 2 080 m/s 
E) 4 160 m/s

Question 11

A wave generated in a medium is a longitudinal wave when

Accepted Answer

A) there is a net transport of matter by the wave. 
B) the molecules of the medium are unable to exert forces on each other. 
C) molecular displacements are parallel to the wave velocity. 
D) molecular displacements are perpendicular to the wave velocity. 
E) the density of the medium is less than the density of water. 
A) there is a net transport of matter by the wave. 
B) the molecules of the medium are unable to exert forces on each other. 
C) molecular displacements are parallel to the wave velocity. 
D) molecular displacements are perpendicular to the wave velocity. 
E) the density of the medium is less than the density of water.

Question 12

You are holding on to one end of a long string that is fastened to a rigid steel light pole.After producing a wave pulse that was 5 mm high and 4 cm wide,you want to produce a pulse that is 6 cm wide but still 5 mm high.You must move your hand up and down once,

Accepted Answer

A) the same distance up as before,but take a shorter time. 
B) the same distance up as before,but take a longer time. 
C) a smaller distance up,but take a shorter time. 
D) a greater distance up,but take a longer time. 
E) a greater distance up,but take the same time. 
A) the same distance up as before,but take a shorter time. 
B) the same distance up as before,but take a longer time. 
C) a smaller distance up,but take a shorter time. 
D) a greater distance up,but take a longer time. 
E) a greater distance up,but take the same time.

Question 13

Suppose that you were selected for a "Survivor"-type TV show.To help keep your group connected,you suggest that long vines can be tied together and used to transmit signals in cases of emergency.To get the signals to travel faster,you should

Accepted Answer

A) select lighter vines. 
B) increase the tension on the vines. 
C) hang weights from the vines at evenly spaced intervals. 
D) do all of the above. 
E) do (a)or (b)above,preferably both. 
A) select lighter vines. 
B) increase the tension on the vines. 
C) hang weights from the vines at evenly spaced intervals. 
D) do all of the above. 
E) do (a)or (b)above,preferably both.

Question 14

Exhibit 16-3
Four wave functions are given below.
I. y(x,t)= 5sin(4x - 20t + 4)
II. y(x,t)= 5sin(3x - 12t + 5)
III. y(x,t)= 5cos(4x + 24t + 6)
IV. y(x,t)= 14cos(2x - 8t + 3)
Use this exhibit to answer the following question.
-Refer to Exhibit 16-3.Rank the wave functions in order of the magnitude of the wavelengths,from least to greatest.

Accepted Answer

A) IV,II,I,III 
B) IV,I,II,III 
C) I,II,III,IV 
D) IV,II,III = I 
E) I = III,II,IV 
A) IV,II,I,III 
B) IV,I,II,III 
C) I,II,III,IV 
D) IV,II,III = I 
E) I = III,II,IV

Question 15

The variation in the pressure of helium gas,measured from its equilibrium value,is given by $\Delta$P = 2.9 *10 - 5 cos (6.20x - 3 000t)where x and t have units m and s,and $\Delta$P is measured in N/m2.Determine the frequency (in Hz)of the wave.

Accepted Answer

A) 1 500 
B) 477 
C) 1.01 
D) 0.32 
E) 239 
A) 1 500 
B) 477 
C) 1.01 
D) 0.32 
E) 239

Question 16

Which of the following is a solution to the wave equation, $\frac { \partial ^ { 2 } y } { \partial x ^ { 2 } } = \frac { 1 } { v ^ { 2 } } \frac { \partial ^ { 2 } y } { \partial t ^ { 2 } }$ ?

Accepted Answer

A)  $\frac { e ^ { - x } } { x } \sin x$ 
B) (cos kx)(sin  $ \omega $t) 
C) e - x sin  $ \omega $t 
D) e - x sin (kx -  $ \omega $t) 
E) e - x cos t 
A)  $\frac { e ^ { - x } } { x } \sin x$ 
B) (cos kx)(sin  $ \omega $t) 
C) e - x sin  $ \omega $t 
D) e - x sin (kx -  $ \omega $t) 
E) e - x cos t

Question 17

(Do not try the following: it could kill you.This question is only about a hypothetical possibility. )If you were standing below an object emitting a fixed frequency sound falling at terminal velocity,as it approached you,you would hear the sound

Accepted Answer

A) drop in frequency. 
B) stay at the same frequency. 
C) increase in frequency. 
D) decrease in loudness. 
E) stay at the same loudness. 
A) drop in frequency. 
B) stay at the same frequency. 
C) increase in frequency. 
D) decrease in loudness. 
E) stay at the same loudness.

Question 18

You are holding on to one end of a long string that is fastened to a rigid steel light pole.After producing a wave pulse that was 5 mm high and 4 cm wide,you want to produce a pulse that is 6 cm wide and 7 mm high.You must move your hand up and down once,

Accepted Answer

A) the same distance up as before,but take a shorter time. 
B) the same distance up as before,but take a longer time. 
C) a smaller distance up,but take a shorter time. 
D) a greater distance up,but take a longer time. 
E) a greater distance up,but take the same time. 
A) the same distance up as before,but take a shorter time. 
B) the same distance up as before,but take a longer time. 
C) a smaller distance up,but take a shorter time. 
D) a greater distance up,but take a longer time. 
E) a greater distance up,but take the same time.

Question 19

The lowest A on a piano has a frequency of 27.5 Hz.If the tension in the 2.00-m string is 308 N,and one-half wavelength occupies the string,what is the mass of the wire?

Accepted Answer

A) 0.025 kg 
B) 0.049 kg 
C) 0.051 kg 
D) 0.081 kg 
E) 0.037 kg 
A) 0.025 kg 
B) 0.049 kg 
C) 0.051 kg 
D) 0.081 kg 
E) 0.037 kg

Question 20

A truck moving at 36 m/s passes a police car moving at 45 m/s in the opposite direction.If the frequency of the siren is 500 Hz relative to the police car,what is the change in frequency (in Hz)heard by an observer in the truck as the two vehicles pass each other? (The speed of sound in air is 343 m/s. )

Accepted Answer

A) 242 
B) 238 
C) 240 
D) 236 
E) 234 
A) 242 
B) 238 
C) 240 
D) 236 
E) 234

Exam 13: Mechanical Waves

The speed of a 10-kHz sound wave in seawater is approximately 1 500 m/s.What is its wavelength in sea water?

Exhibit 16-2 The figure below shows a sine wave on a string at one instant of time. Use this exhibit to answer the following question(s). -Refer to Exhibit 16-2.Which of the graphs below shows a wave where the frequency and wave velocity are both doubled?

Calculate the displacement amplitude (in m)of a 20 kHz sound wave in helium if it has a pressure amplitude of 8.0 *10 - 3 N/m2.( ρ\rhoρ = 0.179 kg/m3,v = 972 m/s. )

When a workman strikes a steel pipeline with a hammer,he generates both longitudinal and transverse waves.The two types of reflected waves return 2.4 s apart.How far away is the reflection point? (For steel,vL = 6.2 km/s,vT = 3.2 km/s)

To transmit four times as much energy per unit time along a string,you can

When you hear the horn of a car that is approaching you,the frequency that you hear is larger than that heard by a person in the car because for the sound you hear

A car moving at 36 m/s passes a stationary police car whose siren has a frequency of 500 hz.What is the change in the frequency (in Hz)heard by an observer in the moving car as he passes the police car? (The speed of sound in air is 343 m/s. )

Calculate the pressure amplitude (in N/m2)of a 500 Hz sound wave in helium if the displacement amplitude is equal to 5.0 *10 - 8 m.( ρ\rhoρ = 0.179 kg/m3,v = 972 m/s. )

A piano string of density 0.005 0 kg/m is under a tension of 1 350 N.Find the velocity with which a wave travels on the string.

A wave generated in a medium is a longitudinal wave when

You are holding on to one end of a long string that is fastened to a rigid steel light pole.After producing a wave pulse that was 5 mm high and 4 cm wide,you want to produce a pulse that is 6 cm wide but still 5 mm high.You must move your hand up and down once,

Suppose that you were selected for a "Survivor"-type TV show.To help keep your group connected,you suggest that long vines can be tied together and used to transmit signals in cases of emergency.To get the signals to travel faster,you should

The variation in the pressure of helium gas,measured from its equilibrium value,is given by Δ\DeltaΔ P = 2.9 *10 - 5 cos (6.20x - 3 000t)where x and t have units m and s,and Δ\DeltaΔ P is measured in N/m2.Determine the frequency (in Hz)of the wave.

Which of the following is a solution to the wave equation, ∂2y∂x2=1v2∂2y∂t2\frac { \partial ^ { 2 } y } { \partial x ^ { 2 } } = \frac { 1 } { v ^ { 2 } } \frac { \partial ^ { 2 } y } { \partial t ^ { 2 } }∂x2∂2y​=v21​∂t2∂2y​ ?

(Do not try the following: it could kill you.This question is only about a hypothetical possibility. )If you were standing below an object emitting a fixed frequency sound falling at terminal velocity,as it approached you,you would hear the sound

You are holding on to one end of a long string that is fastened to a rigid steel light pole.After producing a wave pulse that was 5 mm high and 4 cm wide,you want to produce a pulse that is 6 cm wide and 7 mm high.You must move your hand up and down once,

The lowest A on a piano has a frequency of 27.5 Hz.If the tension in the 2.00-m string is 308 N,and one-half wavelength occupies the string,what is the mass of the wire?

Introduction and Vectors

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Energy in Thermal Processes: the First Law of Thermodynamics

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Electric Forces and Electric Fields

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Filters

Calculate the displacement amplitude (in m)of a 20 kHz sound wave in helium if it has a pressure amplitude of 8.0 *10 ^- ³ N/m².( $\rho$ = 0.179 kg/m³,v = 972 m/s. )

When a workman strikes a steel pipeline with a hammer,he generates both longitudinal and transverse waves.The two types of reflected waves return 2.4 s apart.How far away is the reflection point? (For steel,v_L = 6.2 km/s,v_T = 3.2 km/s)

Calculate the pressure amplitude (in N/m²)of a 500 Hz sound wave in helium if the displacement amplitude is equal to 5.0 *10 ^- ⁸ m.( $\rho$ = 0.179 kg/m³,v = 972 m/s. )

The variation in the pressure of helium gas,measured from its equilibrium value,is given by $\Delta$ P = 2.9 *10 ^- ⁵ cos (6.20x - 3 000t)where x and t have units m and s,and $\Delta$ P is measured in N/m².Determine the frequency (in Hz)of the wave.

Which of the following is a solution to the wave equation, $\frac { \partial ^ { 2 } y } { \partial x ^ { 2 } } = \frac { 1 } { v ^ { 2 } } \frac { \partial ^ { 2 } y } { \partial t ^ { 2 } }$ ?