Sound

Sound (O Level)

Congratulations - you have completed Sound (O Level). You scored %%SCORE%% out of %%TOTAL%%. Your performance has been rated as %%RATING%%
Your answers are highlighted below.
Question 1
We can hear sound when a ball strikes the floor because
A
the air particles from the floor flowed into our ears.
B
the air particles from the floor vibrate and produce longitudinal waves to flow through the air into our ears.
C
the air particles from the floor vibrate and produce transverse waves to flow through the air into our ears.
D
the wavelength of the sound wave is large enough to produce the sound.
Question 1 Explanation: 
Sound is produced by the vibration of a sound. The vibrating source excites the air surrounding it to produce longitudinal sound wave and propagate to your ears. Take note that the air near the source vibrates to cause the neighbouring air particles to vibrate and so on to ‘pass’ the signal to the ear. Also take note that the size of the wavelength does not affect the loudness of the sound. It is the amplitude of the sound wave that affects the loudness.
Question 2
Which of the following are always true for sound waves?
  1. Sound waves are produced by vibration.
  2. Sound waves are longitudinal waves.
  3. Sound waves have an approximate speed of 300 m/s.
A
1 and 2 only
B
2 and 3 only
C
1 and 3 only
D
1, 2 and 3
Question 2 Explanation: 
1. Sound waves are produced by mechanical vibration. (Correct) When a source vibrates, the medium surrounding the sources will be affected by the vibration and starts to vibrate as well to produce sound waves. 2. Sound waves are longitudinal waves. (Correct) 3. Sound waves have an approximate speed of 300 m/s. (Incorrect) Sound wave in air has an approximate speed of 300 m/s. Sound wave has much higher speed in liquid and solid.
Question 3
A guitar string is being set to vibration by plucking it. What type of wave are the vibration of the string and sound?

 

Vibration of string

Sound wave

A

transverse wave

transverse wave

B

transverse wave

longitudinal wave

C

longitudinal wave

transverse wave

D

longitudinal wave

longitudinal wave

A
A
B
B
C
C
D
D
Question 3 Explanation: 
Sound is produced by the vibration of a sound. The vibrating source which is the guitar string vibrates up and sown but the wave direction (left and right) is perpendicular to the vibration of a string. This type of wave is known as a transverse wave. The vibrating string pushes the surrounding air and excites the air surrounding it. The air propagates in the same direction as the vibration of the string. When the direction of source is parallel to the direction of wave, the wave is known as a longitudinal wave.
Question 4
Which of the following is not possible?
A
A man knocks at one end of a long metal pipe and another man hears the knock at the other end.
B
An explosion is heard by an astronaut when a laser beam hits an enemy fighter in space.
C
A whale hears another whale in the deep sea.
D
A mole hears another mole underground.
Question 4 Explanation: 
Sound needs a medium to transmit. The medium can be solid, liquid or gas. Sound cannot transmit through vacuum because there are no vibrating particles to pass on the energy. It is impossible for sound to be transmitted space.
Question 5
Which of the following is true?
A
Speed of sound is approximately 330 m/s.
B
Speed of sound in steel is approximately 1600 m/s.
C
Speed of sound in water is approximately 1400 m/s.
D
Speed of sound in oxygen is approximately 150 m/s.
Question 5 Explanation: 
Speed of sound in air is approximately 330 m/s. Speed of sound in water is approximately 1500 m/s. Speed of sound in steel is approximately 5000 m/s. Speed of sound in oxygen is approximately 317 m/s at 293 K. The nearest to the correct answer is choice (C). Speed of sound in the medium can vary when there is difference in temperature, density and humidity. That is why the speed is always approximate.
Question 6
The speed of sound in air, water and steel is different. Which of the following sequence is the speed of sound in ascending order?
A
speed of sound in air, speed of sound in water, speed of sound in steel
B
speed of sound in steel, speed of sound in water, speed of sound in air
C
speed of sound in air, speed of sound in steel, speed of sound in water
D
speed of sound in water, speed of sound in air, speed of sound in steel
Question 6 Explanation: 
Speed of sound in air is approximately 330 m/s. Speed of sound in water is approximately 1500 m/s. Speed of sound in steel is approximately 5000 m/s.
Question 7
The speed of sound in oxygen, mud and water is different. Which of the following sequence is the speed of sound in ascending order?
A
speed of sound in oxygen, speed of sound in mud, speed of sound in water
B
speed of sound in ice, speed of sound in stone, speed of sound in alcohol
C
speed of sound in fruit juice, speed of sound in iron, speed of sound in air
D
speed of sound in steam, speed of sound in ink, speed of sound in mercury
Question 7 Explanation: 
In general, the speed of sound in gas is lower than the speed of sound in liquid and the speed of sound in liquid is lower than the speed of sound in solid.
Question 8
An electric bell is suspended in a bell jar as shown. An observer outside the bell jar can see the clapper striking the bell but cannot hear any sound produced by the striking. What is a possible reason? 8
A
The bell jar is filled with water.
B
The bell jar has very thick glass.
C
The bell jar is fitted with inert gas.
D
There is a vacuum in the bell jar.
Question 8 Explanation: 
Sound needs a medium to transmit. The most probable reason is that the air inside the bell jar has been sucked out and therefore sound cannot be transmitted out.
Question 9
Which of the following frequency can be heard by a normal human being?
A
10000 Hz
B
100000 Hz
C
1000000 Hz
D
10000000 Hz
Question 9 Explanation: 
The audible frequency range of a normal human being is from 20 Hz. To 20000 Hz.
Question 10
Which of the following frequency can be heard by a normal human being?
  1. 1 Hz
  2. 100 Hz
  3. 10000 Hz
A
1 and 2 only
B
2 and 3 only
C
1 and 3 only
D
1, 2 and 3 only
Question 10 Explanation: 
The audible frequency range of a normal human being is from 20 Hz. To 20000 Hz. 100 Hz and 10000 Hz are within the range.
Question 11
An insect makes sound that is higher than the maximum audible frequency of human beings. Given that the speed of sound in air is approximately 300 m/s, which of the following could be the wavelength of the sound?
A
0.012 m
B
0.032 m
C
0.32 m
D
5.0 m
Question 11 Explanation: 
A. v = fλ 300 = (f)(0.012) => f = 25,000 Hz 300 = (f)(0.032) => f = 9375 Hz 300 = (f)(0.32) => f = 937.5 Hz 300 = (f)(5.0) => f = 60 Hz The audible frequency range of a normal human being is from 20 Hz. To 20000 Hz. When the wavelength is 0.012 m or 1.2 mm, the frequency is out of the maximum audible frequency range of a normal human being.
Question 12
A cow heard something that the farmer could not hear. Given that the wavelength of the sound heard by the cow is 1.0 cm, which of the following is a possible audible frequency range of the cow?
A
25 Hz to 5000 Hz
B
20 Hz to 20,000 Hz
C
20,000 Hz to 30,000 Hz
D
30 Hz to 30,000 Hz
Question 12 Explanation: 
The speed of sound in air is approximately 300 m/s. 1 cm = 0.01 m v = fλ 300 = (f)(0.01) => f = 30000 Hz. Choice C and D include 30000 Hz but the cow can respond to what the farmer normally can hear (20 Hz to 20000 Hz) and therefore the cow’s lowest audible frequency cannot be 20000 Hz. Only choice D is possible.
Question 13
In an experiment to determine the speed of sound, a gun was fired and an observer at a distance of x away measured the time interval between seeing the flash of the gun and hearing the shot. What is a possible value of x?
A
6 m
B
60 m
C
600 m
D
6000 m
Question 13 Explanation: 
The speed of sound in air is approximately 300 m/s. It is impossible for the observer to start and stop the stopwatch when x = 6 m or 60 m. It is also impossible for the observer to see the flash and hear the gun shot when he is 6 km (6000 m) away from the gun. The only possible answer is 600 m.
Question 14
In an experiment to determine the speed of sound, a gun was fired and an observer 900 m away measured the time interval between seeing the flash of the gun and hearing the shot. The duration indicated by a stopwatch is 2.5 s. What is a speed of sound in air?
A
300 m/s
B
330 m/s
C
360 m/s
D
390 m/s
Question 14 Explanation: 
Distance travelled = 900 m Time taken = 2.5 s Speed of sound = distance travelled / time taken = 900 / 2.5 = 360 m/s
Question 15
In an experiment to determine the speed of sound, a gun was fired and an observer at a distance away measured the time interval between seeing the flash of the gun and hearing the shot. The speed of sound in air is calculated by distance ÷ time. Which of the following will affect the result?
  1. Wind blowing from the gunner to the observer.
  2. Wind blowing from the observer to the gunner.
  3. The loudness of the gunshot.
A
1 and 2 only
B
2 and 3 only
C
1 and 3 only
D
1, 2 and 3 only
Question 15 Explanation: 
When the wind is blowing from the gunner to the observer, the sound will be assisted by the wind to move faster to the observer. When the wind is blowing from the observer to the gunner, the sound will be slowed down by the wind and moves slower to the observer. The loudness of the sound will not affect the speed of the sound.
Question 16
The loudness of a sound is determined by its
A
wavelength
B
speed
C
frequency
D
amplitude
Question 16 Explanation: 
The loudness of the sound is determined by the amplitude of the sound wave. The larger the amplitude, the louder the sound is.
Question 17
The pitch of a sound is determined by its
A
wavelength
B
speed
C
frequency
D
amplitude
Question 17 Explanation: 
The pitch of a sound is determined by the frequency of the sound wave. The higher the frequency, the louder the pitch is.
Question 18
Which of the sound wave below is the loudest? 18
A
A
B
B
C
C
D
D
Question 18 Explanation: 
The loudness of the sound is determined by the amplitude of the sound wave. The larger the amplitude, the louder the sound is.
Question 19
Which of the sound wave below has the highest pitch? 19
A
A
B
B
C
C
D
D
Question 19 Explanation: 
The pitch of a sound is determined by the frequency of the sound waves. The higher the frequency, the louder the pitch is. Choice C has the highest number of waves out of the 4 choices. It has 2.5 waves.
Question 20
Which of the sound wave below is high pitch but soft? 20
A
A
B
B
C
C
D
D
Question 20 Explanation: 
A sound that is high in pitch but soft is indicated by a waveform that has high frequency but small amplitude.
Question 21
A sonar signal from a ship is sent underwater towards the sea bed. It takes 0.7 s for the signal to bounce back from the sea bed. If sound travels at 1500 m/s in water, how deep is the sea?
A
525 m
B
1050 m
C
1071 m
D
2143 m
Question 21 Explanation: 
A. When the sound takes 0.7 s to reach the bottom of the sea and then returns to the ship, the time taken for the sound to reach the bottom of the sea is 0.35 s. Distance = speed x time = 1500 x 0.35 = 525 m
Question 22
A man P faces a vertical wall which is 500 m away from him. A second man Q stands 200 m behind P. When P fires a gun, Q hears the shot and an echo. What is the time interval between them if the speed of sound is 340 m/s?
A
0.36 s
B
1.47 s
C
2.94 s
D
5.88 s
Question 22 Explanation: 
The extra distance travelled by the echo = 500 x 2 = 1000 m Distance = speed x time => 340 x t = 1000 t = 2.94 s
Question 23
A hammer strikes one end of a very long metal pipe. A detector at the other end detects two sounds at an interval of 2 s. Given the speed of sound in air and the speed of sound in metal is 300 m/s and 5100 m/s respectively, what is the length of the metal pipe?
A
21 m
B
638 m
C
4800 m
D
9600 m
Question 23 Explanation: 
Time taken by sound to travel in air = Length of metal pipe L ÷ 300 Time taken by sound to travel in metal = L ÷ 5100 (L ÷ 300) – (L ÷ 5100) = 2 (16L ÷ 5100) = 2 L = 637.5 m
Question 24
A man stands between two vertical walls. After making a loud clap, he hears two echoes at an interval of 1 s. If the distance between the two walls is 1000 m, what is his distance from the nearer wall? (Speed of sound is 300 m/s)
A
213 m
B
425 m
C
850 m
D
1700 m
Question 25
A student bangs a drum in the middle of a rectangular hall. Two echoes are detected at 40 ms and 70 ms respectively. If the length of the concert hall is 24 m and there is no echo from the ceiling, what is the speed of sound in air?
A
343 m/s
B
600 m/s
C
686 m/s
D
1200 m/s
Question 25 Explanation: 
Time taken for sound to travel half the length of the hall = ½ x 70 ms = 35 ms Distance travelled by the sound in 35 ms = ½ x 24 m = 12 m Speed = Distance ÷ Time = 12 m ÷ 35 ms = 12 m ÷ (0.035 s) = 343 m/s
Question 26
Two men, A and B, are facing a flat and hard wall as shown. When man A makes a clap, man B hears two claps. If the speed of sound is 320 m/s, what is the time interval between the two claps heard by man B? 26
A
0.32 s
B
0.67 s
C
1.25 s
D
2.50 s
Question 27
Two men, A and B, are facing a flat and hard wall as shown. When man A makes a clap, man B hears two claps. If the speed of sound is 320 m/s, what is the time interval between the two claps heard by man B? 27
A
2.14 s
B
2.28 s
C
3.16 s
D
3.75 s
Question 28
A series of compressions and rarefactions of a sound wave is shown below. What is the wavelength of the wave? 28
A
3 m
B
4 m
C
9 m
D
12 m
Question 28 Explanation: 
The wave length of a sound wave is given by the distance between successive compressions or rarefactions. The diagram shows 3 wavelengths within 12 m. Each wavelength = 12 m ÷ 3 = 4 m
Question 29
A series of compressions and rarefactions of a sound wave is shown below. Given that the speed of sound is 300 m/s. What is the frequency of this sound wave? 29
A
12.5 Hz
B
25.0 Hz
C
50.0 Hz
D
72.0 Hz
Question 29 Explanation: 
The wave length of a sound wave is given by the distance between successive compressions or rarefactions. The diagram shows 2 wavelengths within 24 m. Each wavelength = 24 m ÷ 2 = 12 m Frequency = Speed ÷ Wavelength = (300) ÷ (12 m) = 25 Hz
Question 30
A series
A
A
B
B
C
C
D
D
Question 30 Explanation: 
Time taken for sound to travel from the lightening to the observer = 2.5 s Speed of sound in air is approx. 330 m/s, therefore distance travelled by the sound = speed x time = 330 x 2.5 = 825 m Choice B is closest to the calculated approximate distance.
Question 31
When sound wave travels from air into water, how do the frequencies, wavelength and speed change?

 

Frequency

Wavelength

Speed

A

no change

decreases

decreases

B

increases

no change

decreases

C

no change

increases

increases

D

increases

no change

increases

A
A
B
B
C
C
D
D
Question 31 Explanation: 
The frequency will not change as the source is not disturbed. Sound travels faster in water than in air as vibration travels faster when the particles are closer together. According to the relationship v = fλ, when the frequency is constant and the speed increases, the wave length will increase.
Question 32
A bat produces ultra sound and audible sound at the same time. Which of the following statements is true?
A
Ultrasound travels faster than the audible sound.
B
Ultrasound and audible sound have the same frequency.
C
The wavelength of the ultrasound is longer than the wavelength of the audible sound.
D
Ultrasound and audible sound will reach the same distance at the same time.
Question 32 Explanation: 
The speed of ultrasound is the same as an audible sound when travelling in air. Ultrasound is a type of sound wave with frequencies greater than 20 kHz. Wavelength of ultrasound is shorter than that of the audible sound.
Question 33
A marine survey ship sends a sound wave straight to the sea bed. It detects an echo 4.0 s later. Which is the possible depth of the sea?
A
600 m
B
1500 m
C
3000 m
D
10000 m
Question 33 Explanation: 
The speed of sound in water is approximately 1500 m/s. The depth of the sea is approximately 1500 x 2 = 3000 m.
Question 34
A bat
A
m
B
m
C
m
D
m
Question 34 Explanation: 
Time taken for sound to travel to and fro from the bat to the obstacle = 0.8 s Time taken for sound to travel to the obstacle = 0.4s. Speed of sound in air = 300 m/s Distance from the bat to the obstacle = speed x time = 300 x 0.4 = 120 m
Question 35
An insect
A
m
B
m
C
m
D
m
Question 35 Explanation: 
The speed of sound in air is approx. 300 m/s. Using the relationship v = fλ 300 = (f)(0.06) => f = 5000 Hz 300 = (f)(0.6) => f = 500 Hz 300 = (f)(6) => f = 50 Hz 300 = (f)(60) => f = 5 Hz The audible frequency range of a normal human being is from 20 Hz to 20,000 Hz. When the wavelength is 60 m, the frequency is below the minimum audible frequency of a normal human being.
Question 36
In an experiment to determine the speed of sound, a gun was fired and an observer at a distance away measured the time interval between seeing the flash of the gun and hearing the shot. The speed of sound in air is calculated by distance ÷ time. Which of the following will not affect the result?
  1. The frequency of the gunshot.
  2. The temperature of the environment.
  3. The loudness of the gunshot.
A
1 and 2 only
B
2 and 3 only
C
1 and 3 only
D
1, 2 and 3 only
Question 36 Explanation: 
1. The frequency of the gunshot. (Correct) The frequency of the sound does not affect its speed. 2. The temperature of the environment. (Incorrect) The higher the temperature, the faster will be the speed of sound. 3. The loudness of the gunshot. (Correct) The loudness of the sound does not affect the speed of the sound.
Question 37
Ultrasound is sent from a ship directly downwards into the water. The diagram below shows the duration for ultrasound to return back to the receiver on the ship as the ship travelled from point X to point Y along the surface of the water. At which position is the water deepest? 37
A
A
B
B
C
C
D
D
Question 37 Explanation: 
Point B has the deepest water because ultrasound took the longest time to return back to the receiver board.
Once you are finished, click the button below. Any items you have not completed will be marked incorrect. Get Results
There are 37 questions to complete.

Leave a Reply

Your email address will not be published. Required fields are marked *

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <strike> <strong>

Home Home Sound
© Free Physics Questions