1
A group of students is conducting an experiment to understand sound production. They take a tuning fork, strike it, and bring it near a suspended pith ball. They observe that the pith ball is pushed away.(a) What does the observation with the pith ball indicate about the tuning fork? [1 mark](b) Explain how this observation relates to the production of sound. [2 marks](c) Based on this, state the general principle of sound production in musical instruments. 2marks
2
Two astronauts are on a spacewalk outside the International Space Station. They are working on a repair. One astronaut accidentally drops a wrench, and it makes a metallic clanking sound as it hits another part of the station.(a) If one astronaut were to shout to the other, would the other astronaut hear the shout directly? Explain why or why not. [2 marks](b) Would they be able to hear the clanking sound of the wrench? Justify your answer. [2 marks](c) How do astronauts communicate with each other when on a spacewalk? 1mark
3
A student is trying to understand how sound travels. They have a long slinky toy. They hold one end of the slinky and push it forward and then pull it back, creating a disturbance that travels along the slinky.(a) Describe what the student would observe happening to the coils of the slinky in the regions where the disturbance is passing. [2 marks](b) These regions of closeness and spreading out in the slinky are analogous to which phenomena in sound wave propagation? [1 mark](c) Explain why sound waves are called longitudinal waves, using the slinky analogy. 2marks
4
Assertion (A): Sound cannot travel through a vacuum.Reason (R): Sound waves are mechanical waves that require a medium to propagate.(i) Both A and R are true, and R is the correct explanation of A.(ii) Both A and R are true, but R is not the correct explanation of A.(iii) A is true, but R is false.(iv) A is false, but R is true. 2marks
5
A student observes that when a rubber band is plucked, it vibrates and produces sound. When the vibrations stop, the sound also stops. They also notice that a thinner rubber band, when plucked with the same force, produces a sound that seems to have a higher pitch.(a) What property of the rubber band is directly related to the pitch of the sound produced? [1 mark](b) How does the vibration of the rubber band relate to its frequency and time period? [2 marks](c) Explain why a thinner rubber band might produce a higher pitch sound. 2marks
6
A local community is planning to build a new auditorium. They are concerned about the acoustics of the hall. They have been advised that the design of the walls and ceiling plays a crucial role in how sound is perceived.(a) What phenomenon related to sound reflection needs to be managed in an auditorium to ensure clear sound for the audience? [1 mark](b) Explain how multiple reflections of sound can affect the clarity of speech or music in a large hall. [2 marks](c) What architectural features can be incorporated to control this phenomenon and improve sound quality? 2marks
7
A group of friends is playing near a large cliff. One of them shouts loudly, and after a few seconds, they hear their voice echoing back.(a) What is this phenomenon called? [1 mark](b) State the condition required for an echo to be heard distinctly. [1 mark](c) If the friends hear the echo after 0.8 seconds and the speed of sound in air is 340 m/s, calculate the distance of the cliff from them. 3marks
8
Assertion (A): A louder sound has a larger amplitude.Reason (R): Loudness is the human perception of the intensity of a sound wave, and intensity is related to the square of the amplitude.(i) Both A and R are true, and R is the correct explanation of A.(ii) Both A and R are true, but R is not the correct explanation of A.(iii) A is true, but R is false.(iv) A is false, but R is true. 2marks
9
A mobile phone is used to measure the frequency of different musical notes. When the note 'Sa' is played, the frequency recorded is 256 Hz. When the note 'Pa' is played, the frequency recorded is 384 Hz.(a) What is the unit of frequency, and what does it represent? [2 marks](b) Calculate the time period for the note 'Sa'. [1 mark](c) Calculate the ratio of the frequency of 'Pa' to the frequency of 'Sa'. 2marks
10
Bats navigate and hunt in the dark using a remarkable ability. They emit high-frequency sounds and interpret the echoes that return.(a) What is this ability of bats called? [1 mark](b) What type of sound waves are used by bats, and why are they effective for this purpose? [2 marks](c) Name another application of these types of sound waves used by humans. 1mark
11
In a noisy industrial environment, workers are often advised to wear ear protection. Unwanted and unpleasant sounds are termed as "noise".(a) What is the term used to describe the harmful effect of excessive noise on health and hearing? [1 mark](b) How is the loudness of sound measured, and what is the unit? [1 mark](c) Suggest two ways to reduce noise pollution in an urban environment. 2marks
12
A tuning fork of frequency 440 Hz is struck and held near the ear.(a) What phenomenon occurs that allows the sound to be heard? [1 mark](b) If the sound wave travels at 344 m/s in air, calculate the wavelength of the sound produced by the tuning fork. 2marks
13
Consider the following scenario: A student is trying to determine the minimum distance at which an echo can be heard. They know that the brain can distinguish between two sounds if they arrive at least 0.1 seconds apart.(a) If the speed of sound in air is 340 m/s, calculate the minimum distance the reflecting surface should be from the source to hear a distinct echo. 3marks
14
Assertion (A): When a sound wave travels from a source, it carries energy through the medium.Reason (R): The particles of the medium vibrate about their mean positions and transfer this energy to adjacent particles.(i) Both A and R are true, and R is the correct explanation of A.(ii) Both A and R are true, but R is not the correct explanation of A.(iii) A is true, but R is false.(iv) A is false, but R is true. 2marks
15
A researcher is studying the sound produced by different musical instruments. They have a graph showing the density variation of the medium over distance for a sound wave.(a) In the given density-distance graph, label the regions representing compressions and rarefactions. [1 mark](b) If the distance between two consecutive compressions is 5 cm, what is this distance called? [1 mark](c) If the speed of sound is 340 m/s, calculate the frequency of the sound wave. 2marks
16
A deep sea exploration vehicle uses sonar to detect the seabed. It sends out a pulse of ultrasonic sound, which travels to the seabed and reflects back.(a) Why are ultrasonic waves particularly useful for sonar? [2 marks](b) If the sonar signal takes 3 seconds to return to the vehicle and the speed of sound in seawater is 1500 m/s, calculate the depth of the ocean at that location. 3marks
17
While watching a movie depicting a spacecraft explosion in outer space, a student notices that both a bright flash of light and a loud sound are shown simultaneously.(a) Identify the error in the depiction regarding sound. Explain why it is an error. [2 marks](b) How does light travel in space, and how does this differ from sound? 2marks
18
The graph in Fig. 10.30(a) from the textbook represents a sound wave.(a) What do the peaks and troughs of this graph represent in terms of the medium's density? [2 marks](b) If the distance between two consecutive peaks in the graph is 10 cm, and the speed of sound is 340 m/s, what is the frequency of the sound wave? 2marks
19
The human ear can perceive sounds within a specific range of frequencies. Sound waves with frequencies below this range are called infrasonic, and those above are called ultrasonic.(a) State the approximate frequency range of human hearing. [1 mark](b) Give one example of an animal that can detect infrasonic waves and one that can detect ultrasonic waves. 2marks
20
A student is comparing two sound waves represented by graphs with the same scales on the x and y axes. Graph (a) shows a wave with a large amplitude and short wavelength, while graph (b) shows a wave with a small amplitude and long wavelength.(a) Which sound wave will be perceived as louder? Justify your answer. [2 marks](b) Which sound wave carries more energy? Justify your answer. 2marks
Answers
1
(a) The observation with the pith ball indicates that the tuning fork is vibrating. 1mark(b) Sound is produced by vibrating objects. The vibrating tuning fork pushes the air particles away, which in turn transmit the vibration as a sound wave. [2 marks](c) Musical instruments produce sound by causing parts of the instrument (like strings, membranes, or air columns) to vibrate. [2 marks]
2
(a) No, the other astronaut would not hear the shout directly because sound requires a medium to travel, and the vacuum of space does not provide a medium. 2marks(b) Yes, they would be able to hear the clanking sound of the wrench. This is because sound can travel through solids, and the clanking sound would travel through the metallic structure of the space station from the wrench to the astronauts. [2 marks](c) Astronauts communicate through special devices fitted into their spacesuits, which convert sound into electrical signals and transmit them. [1 mark]
3
(a) The student would observe that the coils of the slinky in the disturbed regions become closer together than usual and then spread out more than usual. 2marks(b) These regions of closeness and spreading out in the slinky are analogous to compressions and rarefactions, respectively, in sound wave propagation. [1 mark](c) Sound waves are called longitudinal waves because the particles of the medium (represented by the coils of the slinky) vibrate back and forth in a direction parallel to the direction of propagation of the disturbance (the wave traveling along the slinky). [2 marks]
4
(i) Both A and R are true, and R is the correct explanation of A. 2marks
5
(a) The pitch of the sound produced is directly related to the frequency of vibration of the rubber band. 1mark(b) A higher frequency of vibration means more oscillations per second, which corresponds to a shorter time period for each oscillation. [2 marks](c) A thinner rubber band is generally less taut and may vibrate more rapidly for the same applied force, resulting in a higher frequency and thus a higher pitch. [2 marks]
6
(a) The phenomenon that needs to be managed is the reflection of sound, specifically to avoid excessive echoes and to ensure sound reaches all parts of the audience effectively. 1mark(b) Excessive multiple reflections can cause sound to persist for too long (reverberation), leading to overlapping sounds and distortion, making speech or music unclear. [2 marks](c) Incorporating sound-absorbing materials (like curtains, soft furnishings) and designing curved surfaces (like ceilings and walls behind the stage) to reflect sound towards the audience can help control reverberation and improve sound quality. [2 marks]
7
(a) This phenomenon is called an echo. 1mark(b) For an echo to be heard distinctly, the time interval between the original sound and the reflected sound must be at least 0.1 seconds. [1 mark](c) Total distance travelled by sound = speed × time = 340 m/s × 0.8 s = 272 m. Since this is the distance to the cliff and back, the distance of the cliff from them is half of this: 272 m / 2 = 136 m. [3 marks]
8
(i) Both A and R are true, and R is the correct explanation of A. 2marks
9
(a) The unit of frequency is Hertz (Hz) or per second (). It represents the number of oscillations or cycles per unit time (usually per second). 2marks(b) Time period (T) = 1 / Frequency (ν) = 1 / 256 Hz = 0.0039 s (approximately). [1 mark](c) Ratio = Frequency of 'Pa' / Frequency of 'Sa' = 384 Hz / 256 Hz = 1.5. [2 marks]
10
(a) This ability of bats is called echolocation. 1mark(b) Bats use ultrasonic waves (high-frequency sound waves) because these waves have shorter wavelengths, allowing them to detect smaller objects and provide more detailed information about the surroundings. [2 marks](c) Another application is sonar, used in underwater exploration and navigation. [1 mark]
11
(a) The harmful effect of excessive noise on health and hearing is called noise pollution. 1mark(b) The loudness of sound is measured in decibels (dB). [1 mark](c) Two ways to reduce noise pollution are:i. Planting trees along roadsides to act as sound barriers.ii. Using sound-absorbing materials in building construction and designing quieter machinery. [2 marks]
12
(a) The vibration of the tuning fork causes the surrounding air particles to vibrate, producing sound waves that propagate to the ear. 1mark(b) Wavelength (λ) = Speed (v) / Frequency (ν) = 344 m/s / 440 Hz = 0.78 m. [2 marks]
13
To hear an echo distinctly, the time taken for sound to travel to the reflecting surface and back must be at least 0.1 seconds.Distance travelled by sound in 0.1 s = Speed × Time = 340 m/s × 0.1 s = 34 m.This distance is for the sound to travel to the surface and back. Therefore, the minimum distance to the reflecting surface is half of this: 34 m / 2 = 17 m. 3marks
14
(i) Both A and R are true, and R is the correct explanation of A. 2marks
15
(a) In a density-distance graph for a sound wave, the regions where the density is above the average density represent compressions (C), and the regions where the density is below the average density represent rarefactions (R). 1mark(b) The distance between two consecutive compressions is called the wavelength (λ) of the sound wave. [1 mark](c) Wavelength (λ) = 5 cm = 0.05 m.Frequency (ν) = Speed (v) / Wavelength (λ) = 340 m/s / 0.05 m = 6800 Hz. [2 marks]
16
(a) Ultrasonic waves are useful for sonar because they can travel long distances in water with minimal absorption, have high directionality, and their short wavelengths allow for the detection of smaller objects and provide higher resolution images. 2marks(b) Time taken for signal to travel and return = 3 s.Time taken to reach the seabed = 3 s / 2 = 1.5 s.Depth of the ocean = Speed × Time = 1500 m/s × 1.5 s = 2250 m. [3 marks]
17
(a) The error is the simultaneous appearance of the bright flash of light and the loud sound. Sound requires a medium to travel, whereas light can travel through a vacuum. In outer space, there is a vacuum, so no sound would be heard from the explosion. 2marks(b) Light travels as electromagnetic waves and can propagate through the vacuum of space. Sound travels as mechanical waves and requires a material medium (like air, water, or solids) to propagate. [2 marks]
18
(a) The peaks of the graph represent regions of maximum density (compressions), and the troughs represent regions of minimum density (rarefactions) in the medium. 2marks(b) Wavelength (λ) = 10 cm = 0.10 m.Frequency (ν) = Speed (v) / Wavelength (λ) = 340 m/s / 0.10 m = 3400 Hz. [2 marks]
19
(a) The approximate frequency range of human hearing is from 20 Hz to 20,000 Hz (20 kHz). 1mark(b)Animal detecting infrasonic waves: Elephant.Animal detecting ultrasonic waves: Bat (or dog, dolphin). [2 marks]
20
(a) The sound wave represented by graph (a) will be perceived as louder because it has a larger amplitude. Loudness is the perception of amplitude. 2marks(b) The sound wave represented by graph (a) carries more energy because energy carried by a wave is proportional to the square of its amplitude. A larger amplitude implies more energy. [2 marks]
