1 Two students are asked to determine the speed of sound in air on the school playing fields.
(a) List the apparatus they need.
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(b) List the readings that the students need to take.
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(c) State how the speed of sound is calculated from the readings.
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(d) State one precaution that could be taken to improve the accuracy of the value obtained.
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(e) The table gives some speeds.
speed/ speed of sound speed of sound
m/s in air in water
10
100
1000
10 000
Place a tick in the table to show the speed which is closest to
(i) the speed of sound in air,
(ii) the speed of sound in water.
[2]
[Total: 6]
PhysicsAndMathsTutor.com
3 Fig. 7.1 shows how the air pressure at one instant varies with distance along the path of a
continuous sound wave.
air pressure
normal P X Y
air pressure distance in direction
of travel of the wave
Fig. 7.1
(a) What type of waves are sound waves?
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(b) On Fig. 7.1, mark on the axis PY
(i) one point C where there is a compression in the wave, [1]
(ii) one point R where there is a rarefaction in the wave. [1]
(c) Describe the motion of a group of air particles situated on the path of the wave shown in
Fig. 7.1.
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(d) The sound wave shown has speed of 340 m / s and a frequency of 200 Hz.
Calculate the distance represented by PX on Fig. 7.1.
distance = ........................[2]
[Total : 7]
PhysicsAndMathsTutor.com
5 Fig. 7.1 shows the cone of a loudspeaker that is producing sound waves in air.
At any given moment, a series of compressions and rarefactions exist along the line XY.
cone
X Y
wires
air
Fig. 7.1
(a) On Fig. 7.1, use the letter C to mark three compressions and the letter R to mark three
rarefactions along XY. [1]
(b) Explain what is meant by
(i) a compression,
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(ii) a rarefaction.
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[2]
(c) A sound wave is a longitudinal wave. With reference to the sound wave travelling along
XY in Fig. 7.1, explain what is meant by a longitudinal wave.
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(d) There is a large vertical wall 50 m in front of the loudspeaker. The wall reflects the
sound waves.
The speed of sound in air is 340 m/s.
Calculate the time taken for the sound waves to travel from X to the wall and to return
to X.
time = …………………[2]
PhysicsAndMathsTutor.com [ Total : 7 ]
(c) The effect in Fig. 8.1 is often shown using water waves on the surface of a tank of water.
These are transverse waves. Explain what is meant by a transverse wave.
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[Total : 7 ]
PhysicsAndMathsTutor.com
