Deck 15: Making Waves

Question 1

Suppose an audible sound wave were being produced at a frequency of 800 cycles per second. If the frequency were doubled, the sound would become

A) softer.
B) louder.
C) lower in pitch.
D) higher in pitch.

Answer 1

higher in pitch.

Question 2

You hear a musician playing a series of notes of increasing frequency. As the frequency increases, the wave speed

A) increases.
B) decreases.
C) stays the same.

Answer 2

stays the same.

Question 3

When a wave reflects from a stationary boundary,

A) the frequency increases.
B) the frequency decreases.
C) the frequency is unchanged.

Answer 3

the frequency is unchanged.

Question 4

Which of the following is a longitudinal wave?

A) a sound wave in a gas
B) a wave on string under tension
C) a light wave
D) All of these choices are correct.
E) None of these choices is correct.

Question 5

The principle of superposition tells us that, if two waves cross paths,

A) the amplitude is the sum of the individual amplitudes.
B) the wavelength is the sum of the individual wavelengths.
C) the frequency is the sum of the individual frequencies.
D) the speed is the speed of the faster wave.

Question 6

On a day when the speed of sound in air is 340 m/s, a lightning bolt is observed and the resultant thunderclap is heard 5 seconds afterwards. About how far away was the lightning bolt?

A) 1020 m
B) 170 m
C) 1700 m
D) 680 m

Question 7

If the speed of sound is 1100 feet per second and a tuning fork oscillates at 440 cycles per second, what is the wavelength $\lambda$ of the sound produced?

A) 0.4 foot
B) 2.5 feet
C) 4.4 feet
D) 11 feet

Question 8

A musical tone is coming from a loudspeaker. If a second loudspeaker nearby were to start playing exactly the same tone, the sound would

A) get louder everywhere.
B) get softer everywhere.
C) stay the same everywhere.
D) get louder in some areas and get softer in others.

Question 9

Which of these lists is in order of increasing wavelength?

A) Second harmonic, third harmonic, fourth harmonic
B) First harmonic, second harmonic, fundamental
C) Third harmonic, second harmonic, first harmonic
D) First harmonic, second harmonic, third harmonic

Question 10

The Doppler effect refers to changes in a sound wave's

A) frequency caused by motion of a source or receiver.
B) frequency caused by a change in speed of sound.
C) amplitude caused by motion of a source or receiver.
D) amplitude caused by a change in speed of sound.

Question 11

To change the fundamental frequency of a guitar string, you can

A) use something other than a pick.
B) strum it over the sound hole.
C) do nothing short of using a completely different guitar.
D) make it shorter, by pressing a finger of your left hand on the string.

Question 12

The pitch of a sound is determined primarily by its

A) frequency.
B) speed.
C) duration.
D) amplitude.

Question 13

The period and the frequency of a sound wave are

A) independent of each other.
B) multiples of each other-period is 2 $\pi$ times the frequency.
C) reciprocals of each other.
D) none of these.

Question 14

Jim the meteorologist has predicted fair weather all day but sees flashes of lightning followed by rolls of thunder. To calculate the distance to the lightning bolt, Jim should measure the time between the instant he first sees a lightning flash and the

A) instant the lightning flash is over.
B) instant he hears the beginning of the next thunder roll.
C) instant he hears the middle of the next thunder roll.
D) instant he hears the end of the next thunder roll.
E) instant he sees the beginning of the next lightning flash.

Question 15

A guitar is perfectly tuned. The tension on its strings is then increased. Which of the following is true?

A) The frequencies of sounds from the guitar are higher than before.
B) The wavelengths of sounds from the guitar are longer than before.
C) The speed of sounds from the guitar is larger than before.
D) The amplitudes of sounds from the guitar are larger.

Question 16

As a wave passes from one medium into another, it often happens that its speed increases with no change in frequency. Under these circumstances, the wavelength

A) increases.
B) decreases.
C) stays the same.

Question 17

Suppose an audible sound wave were being produced at a frequency of 800 cycles per second. If the amplitude were doubled, the sound would become

A) louder.
B) softer.
C) higher in pitch.
D) lower in pitch.

Question 18

Electromagnetic waves are generally

A) longitudinal waves.
B) transverse waves.
C) a 50/50 combination of transverse and longitudinal waves.
D) standing waves.

Question 19

Imagine you are holding a long rope under tension attached to a distant support. You can generate periodic waves by shaking the end up and down. Changing which of the following will least affect the velocity of waves along the string?

A) tension
B) mass per unit length of rope
C) frequency
D) None of these affect the wave speed.

Question 20

When a wave crosses from one medium into another in which the wave speed is lower, the frequency is unchanged. The wavelength

A) increases.
B) decreases.
C) stays the same.

Question 21

A harmonic wave has

A) another wave nearby, so as to create harmony.
B) a close correspondence to simple harmonic motion.
C) to be a sound wave.
D) a higher speed than a noise wave.

Question 22

When playing tennis, if you hit the ball off of the top end of the racket, an uncomfortable standing wave vibration is produced in the racket. This wave is

A) longitudinal.
B) transverse.
C) both longitudinal and transverse.
D) neither longitudinal nor transverse.

Question 23

A vibrating guitar string has exactly one antinode in the middle of the string and two nodes at the end. You have produced an oscillation of the string at its

A) fundamental frequency.
B) first harmonic frequency..
C) second harmonic frequency..
D) third harmonic frequency..

Question 24

An organ pipe of length 3.0 m has one end closed. The longest and next-longest possible wavelengths for standing waves inside the pipe are

A) 6 m and 3 m.
B) 12 m and 6 m.
C) 12 m and 4 m.
D) 9 m and 6 m.
E) 3 m and 1.5 m.

Question 25

Consider possible standing wave patterns for a string fastened at each end. Discussion in the text shows that there is a

A) minimum possible wavelength.
B) maximum possible frequency.
C) maximum possible amplitude.
D) maximum possible wavelength.

Question 26

End A of a Slinky is held motionless near the ceiling. End B is held on the floor so that there is a slight stretch. End B is quickly rotated one half turn about the axis of the Slinky and then returned to its original position, so as to "twist" and then "untwist" the coils. The wave so produced is a

A) longitudinal wave.
B) transverse wave.
C) standing wave.
D) It is none of these.

Question 27

A fast train approaches a car waiting at a grade crossing and sounds its horn. A person in the car will notice that, compared to what it would be if the train were at rest, the horn sound's

A) wavelength appears to be the same.
B) wavelength appears to be longer.
C) frequency appears to be lower.
D) frequency appears to be higher.

Question 28

Sound is produced by a pipe that is closed on one end. The standing waves must have

A) just one node in the pipe.
B) at least one node in the pipe.
C) at most one antinode in the pipe.
D) no antinodes in the pipe.

Question 29

Captain Ahab notices that the waves passing the anchored Pequod are 10 feet from crest to crest, and that each minute 4 crests pass. The wave speed is

A) 80 feet per minute.
B) 40 feet per minute.
C) 20 feet per minute.
D) 5 feet per minute.

Question 30

Waves on a particular string travel with a velocity of 10 m/s. A high-speed photograph shows that successive peaks are 0.40 m apart along the string. The frequency of the waves is

A) 5 Hz.
B) 10 Hz.
C) 15 Hz.
D) 20 Hz.
E) 25 Hz.

Question 31

Human hearing is most sensitive around 2500 Hz. If the speed of sound is 340 m/s, what is the wavelength of this sound?

A) 0.14 m
B) 7.4 m
C) 340 m
D) 2160 m

Question 32

On a day when the speed of sound in air is 340 m/s, what will be the wavelength of sound of frequency 227 Hz?

A) 227 m
B) 3.0 m
C) 1.5 m
D) 0.67 m
E) 0.33 m

Question 33

When two strings of equal length on a guitar are played, two different pitches are heard. Comparing the waves on the lower pitch string to the higher, the waves on the higher pitch string have

A) a larger period.
B) a larger amplitude.
C) a shorter wavelength.
D) a higher speed.

Question 34

A standing wave is set up on a string so that it has 5 nodes. If you start at the central node and move exactly one wavelength in either direction, you will wind up at

A) a node.
B) an antinode.
C) neither a node nor an antinode but still on the string.
D) somewhere off the string.

Question 35

Two waves approach each other as shown above. When they completely overlap, the resulting wave will look like

A)
B)
C)
D)

Question 36

A string is held taut between two supports 2.0 m apart. The longest and next-longest possible wavelengths for standing waves are

A) 4 m and 2 m.
B) 6 m and 3 m.
C) 8 m and 4 m.
D) 16 m and 5.3 m.

Question 37

An organ pipe makes a sound that has a frequency of 450 Hz when the temperature is 20 $\degree$ C. If the temperature is ten degrees colder the wavelength of sound produced in the pipe will

A) get longer.
B) stay the same.
C) get shorter.
D) It is not possible to tell without more information.

Question 38

The speed of electromagnetic waves in air is 3.0 $\times$ 10⁸ m/s. What is the wavelength of FM radio waves having a frequency of 3.0 $\times$ 10⁸ Hz?

A) 0.333 m
B) 1.0 m
C) 3.0 m
D) 6.0 m
E) 10 m

Question 39

Suppose the velocity of waves on a particular rope under a tension of 100 N is 12 m/s. If the tension is decreased to 25 N what will be the new velocity of waves on the rope?

A) 48 m/s.
B) 24 m/s.
C) 18 m/s.
D) 12 m/s.
E) 6 m/s.

Question 40

A tuning fork with a frequency of 512 Hz is used to tune a violin. When played together, beats are heard with a frequency of 4 Hz. The string on the violin is tightened and when played again, the beats have a frequency of 2 Hz. The original frequency of the violin was

A) 508 Hz.
B) 510 Hz.
C) 514 Hz.
D) 516 Hz.

Question 41

To excite the second harmonic in a jumprope, you have to change the frequency from the fundamental. The new frequency must be

A) larger.
B) smaller.
C) the same as the fundamental frequency, but you'll need a larger wavelength.
D) the inverse of the fundamental frequency.

Question 42

Sound waves in water have a higher ________________ than sound waves in air.

Question 43

You have a set of 14 metal weights strung together by nylon fishing line at equal intervals. Each has a weight of 0.20 N. You suspend this array from the ceiling and then observe waves travel up and down by shaking it. The wave seems to move more rapidly at the top, near weights 1-3. This is because

A) gravity is cancelled by tension, so net force is zero.
B) weight 14 is balanced by no other weight, but weight 1 is balance by 13 others below it.
C) there is more tension in the fishing line near weights 1-3 than down by weight 14.
D) the amount of mass per centimeter is higher toward the top, near weights 1-3.

Question 44

You have a set of 14 metal weights strung together by nylon fishing line at equal intervals. Each has a weight of 0.20 N. You suspend this array from the ceiling. Which part of the array has the greatest tension in the fishing line?

A) above weight 1.
B) between weights 1 and 3.
C) exactly at weight 7.
D) just above weight 14.

Question 45

Which general pattern holds for various excited states in standing waves on a rope or string fixed at both ends?

A) Where the nodes are, you also find two antinodes.
B) Guitars and violins have antinodes only in even numbers: 0, 2, 4, and so on.
C) More antinodes means shorter wavelengths.
D) Standing waves involve the interference of waves traveling in the same direction.

Question 46

Mechanical wave motion is a phenomenon in which there is a transport of __________________ without net motion of the medium.

Question 47

An antinode in a standing wave is the location that appears to ____________ (describe behavior) from equilibrium.

Question 48

The distance between successive nodes for a standing wave pattern is ___________________ the wavelength (give multiple or fraction).

Question 49

Standing waves on a string produce a series of possible tones known as __________________.

Question 50

The number of cycles of a periodic wave passing a point in space per second is called the __________________ of the wave.

Question 51

Constructive interference is a result of two waves arriving at a point ______________________.

Question 52

Blowing gently across the top of a soda pop bottle gives you a musical note at a certain fundamental frequency. This is most similar to

A) making a guitar string resonate at its fundamental.
B) an organ pipe.
C) a wind chime.
D) a telephone.
Fill in the Blank Questions

Question 53

The lowest frequency that can be made by a guitar string is called the ____________ (2 words).

Question 54

The product of the frequency of a periodic wave times its wavelength gives the _________________ of the wave.

Question 55

An organ pipe open only at one end will have a displacement node at the _____________ end.

Question 56

When fans do "the wave" at a sports stadium, it is a _____________ (transverse or longitudinal) wave.

Question 57

Increasing the air temperature inside an organ pipe, neglecting any expansion of the pipe, will _________________ the frequency of the fundamental tone.