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Science questions, chapter 10
Nama / NameKelas / ClassTarikh / Date

Sound waves

44 marks. Use Practice to check each answer as you go, or Exam to answer everything against the clock first.

Section A: objective questions

12 marks
Choose the best answer for each question.
1

Question 1

Sound is produced when an object is
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B
Sound is a form of energy caused by vibration, for example a guitar string, a drum skin or your vocal cords.
For the teacher: Remembering, low difficulty, standard 10.1
Textbook p. 224
2

Question 2

Sound waves cannot travel through
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D
Sound needs a medium made of particles. It can travel through solids, liquids and gases but not through a vacuum.
For the teacher: Remembering, low difficulty, standard 10.1
Textbook p. 226
3

Question 3

In which medium does sound travel fastest?
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A
The particles of a solid are packed very closely, so the vibration is passed on quickly. Liquids are slower and gases slowest.
For the teacher: Understanding, low difficulty, standard 10.1
Textbook p. 227
4

Question 4

Which surface is the best absorber of sound?
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C
Soft and rough surfaces such as carpet absorb sound. Marble, painted walls and metal are hard and smooth, so they reflect sound.
For the teacher: Applying, low difficulty, standard 10.1
Textbook p. 228
5

Question 5

What is the unit of frequency?
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B
Frequency is the number of complete waves per second and is measured in hertz (Hz).
For the teacher: Remembering, low difficulty, standard 10.2
Textbook p. 229
6

Question 6

The amplitude of a sound wave increases. What happens to the sound?
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D
Loudness depends on amplitude. Pitch depends on frequency, and the speed depends on the medium.
For the teacher: Understanding, low difficulty, standard 10.2
Textbook p. 230
7

Question 7

Diagram 1 shows the original sound wave and wave X on a C.R.O. screen. What was changed to produce wave X?
Original wave and a wave X of the same frequency but double the height
Diagram 1
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A
Wave X has the same number of waves in the same time (same frequency, so same pitch) but a larger amplitude. A larger amplitude comes from more output power and gives a louder sound.
For the teacher: Analysing, medium difficulty, standard 10.2
Textbook p. 230
8

Question 8

An ambulance with its siren on drives towards a person standing by the road. What does the person notice?
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C
This is the Doppler effect: the frequency heard increases while the source approaches the observer, then decreases when it moves away.
For the teacher: Applying, low difficulty, standard 10.2
Textbook p. 231
9

Question 9

What is an echo?
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B
An echo is sound reflected from a hard surface that reaches the listener a little after the original sound.
For the teacher: Understanding, low difficulty, standard 10.3
Textbook p. 232
10

Question 10

Ultrasound is a sound with a frequency
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D
Ultrasound has a frequency above 20 000 Hz, which is above the upper limit of human hearing.
For the teacher: Remembering, low difficulty, standard 10.3
Textbook p. 232
11

Question 11

Which sound can be heard by a healthy young person?
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A
The hearing range of humans is 20 Hz to 20 000 Hz. 5 Hz is below the range; 25 000 Hz and 50 000 Hz are above it.
For the teacher: Applying, low difficulty, standard 10.3
Textbook p. 233
12

Question 12

Diagram 2 shows the hearing ranges of some animals. Which animals can hear a sound of 60 000 Hz?
Bars showing hearing ranges of humans, dogs, horses, elephants, bats and dolphins on a frequency scale
Diagram 2
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C
Only the bars of bats (2 000 to 110 000 Hz) and dolphins (40 to 100 000 Hz) extend past 60 000 Hz. Dogs stop at 45 000 Hz, horses at 33 500 Hz and elephants at 12 000 Hz.
For the teacher: Analysing, high difficulty, standard 10.3
Textbook p. 233

Section B: structured questions

32 marks
Answer all questions. Write your answers in the spaces provided.
13

Question 13

Diagram 3 shows an alarm clock that is ringing inside a bell jar. A vacuum pump then removes the air from the jar.
Alarm clock under a bell jar on a polystyrene sheet connected to a vacuum pump
Diagram 3
[1 mark] (a)What happens to the loudness of the sound as the air is removed?
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It gets softer
Fewer air particles are left to carry the vibration.
[1 mark] (b)What does this show about the propagation of sound?
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Tick each point you got.
[2 marks] (c)Explain how the sound of the clock reaches your ear before the air is removed.
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Tick each point you got.
For the teacher: Understanding, low difficulty, standard 10.1
Textbook p. 224
14

Question 14

Amir taps one end of a long steel rail. Bala puts his ear to the other end and hears the sound before Chin, who stands in the air next to him, hears it.
[2 marks] (a)Explain why Bala hears the sound earlier than Chin.
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Tick each point you got.
[1 mark] (b)Name a medium in which sound travels slower than in steel but faster than in air.
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Tick each point you got.
For the teacher: Understanding, low difficulty, standard 10.1
Textbook p. 227
15

Question 15

A pupil repeats Activity 10.1(B) using a ticking stopwatch in a cardboard tube. The table shows how loud the ticking was heard through the second tube for three materials.
MaterialTicking heard
Wooden plankLoud
Metal sheetVery loud
TowelVery faint
[1 mark] (a)Which material is the best absorber of sound?
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Towel
The ticking is faintest because the towel absorbs most of the sound.
[1 mark] (b)Which material is the best reflector of sound?
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Metal sheet
The ticking is loudest because the metal sheet reflects most of the sound.
[2 marks] (c)The walls of a cinema hall are covered with layers of thin softboard. Explain why.
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Tick each point you got.
For the teacher: Applying, low difficulty, standard 10.1
Textbook p. 225
16

Question 16

Diagram 4 shows the C.R.O. traces of three sounds P, Q and R recorded over one second. One of the sounds is the moo of a cow.
Waves P with 2 cycles, Q with 5 cycles and R with 5 cycles of double the height, over one second
Diagram 4
[1 mark] (a)Which wave has the lowest frequency?
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P
P has only 2 waves in one second.
[1 mark] (b)State the frequency of Q, with its unit.
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Count the complete waves in one second: 5, so 5 Hz.
Tick each point you got.
[2 marks] (c)Compare Q and R.
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Tick each point you got.
[1 mark] (d)Which wave is more likely to be the cow's moo? Give a reason.
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Tick each point you got.
For the teacher: Analysing, medium difficulty, standard 10.2
Textbook p. 229
17

Question 17

Farah plucks a guitar string.
[2 marks] (a)She tightens the string and plucks it again. State the change in the sound and explain it.
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Tick each point you got.
[2 marks] (b)She plucks the string harder. State the change in the sound and explain it.
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Tick each point you got.
For the teacher: Applying, medium difficulty, standard 10.2
Textbook p. 229
18

Question 18

Raju stands at the roadside. An ambulance with its siren on drives past him.
[1 mark] (a)The frequency of the siren that Raju hears while the ambulance approaches
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increases
The Doppler effect: the source moves towards the observer.
[1 mark] (b)The frequency that Raju hears after the ambulance has passed him
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decreases
The ambulance is now moving away from him.
[1 mark] (c)Does the driver of the ambulance hear the siren change in pitch? Give a reason.
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Tick each point you got.
For the teacher: Understanding, low difficulty, standard 10.2
Textbook p. 231
19

Question 19

Diagram 5 shows a ship using sonar to find the depth d of the sea. The echo of the ultrasound is received 0.8 s after it was sent. The speed of sound in sea water is 1 500 m s⁻¹.
A ship sending ultrasound down to the sea bed and receiving the echo; the depth is marked d
Diagram 5
[1 mark] (a)Humans cannot hear ultrasound. State its frequency.
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Tick each point you got.
[2 marks] (b)Calculate the depth d of the sea.
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600 m
Tick each point you got.
[1 mark] (c)State one other use of the reflection of ultrasound.
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Tick each point you got.
For the teacher: Applying, high difficulty, standard 10.3
Textbook p. 232
20

Question 20

You are asked to design a recording studio so that the recordings are of good quality.
[3 marks] (a)Suggest three changes to make to the studio, with a reason for each.
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Any 3 points
Tick each point you got.
For the teacher: Creating, medium difficulty, standard 10.1
Textbook p. 228
21

Question 21

Two astronauts are outside their spacecraft. They cannot hear each other's voices directly.
[1 mark] (a)Explain why they cannot hear each other directly.
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Tick each point you got.
[1 mark] (b)Suggest one other way they can communicate without radio, with a reason.
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Any 1 points
Tick each point you got.
For the teacher: Evaluating, medium difficulty, standard 10.1
Textbook p. 226