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physics Physics For High Schools (KS4)

Solved problems for the chapter:

Echo

View the theory »

Propagation of Sound

1. Generation and reception of sound

2. Air pressure and displacement of particles during oscillation

3. Sound source

4. Sound propagation

4.1. Reflection of sound

4.2. Speed of sound

5. Forum

↓ Show theory [1] ↓

Detailed solution steps are available at:

https://en.openprof.com/wb/chapter:echo/3621/

Example 1.

Which process causes a sound wave to produce an echo?

diffraction
dispersion
reflection
refraction

Example 2.

A ship sounds its horn when it is from a cliff. A passenger on the ship hears the echo later. What is the speed of the sound?

A ship sends a pulse of sound vertically downwards to the sea bed. An echo is heard later. If the speed of sound in the water is , how deep is the water below the ship?

A boy shouts and hears the echo from a tall building later. The speed of sound in air is . How far away from the boy is the building?

Sound travels by wave motion. Which property of waves causes echoes?

diffraction
dispersion
reflection
refraction

A girl stands in front of a rock face.

The girl claps her hands once. The speed of sound in air is . How long is it before she hears the echo?

A student wishes to measure the speed of sound in air. She plans to measure the time between making a sound and hearing the echo from a cliff.

She will use the equation:

Which type of sound should she make and which distance should she use in her calculation?

	type of sound	distance to use
A	continuous sound
B	continuous sound
C	short, sharp sound
D	short, sharp sound

A girl stands at a distance from a large building. She claps her hands and a short time later hears an echo. Why is an echo produced when the sound waves hit the building?

The sound waves are absorbed
The sound waves are refracted
The sound waves are diffracted
The sound waves are reflected

An engineer standing at P sees an explosion at X.

After the explosion, she hears two bangs. One bang is heard a fraction of a second after the other. The second bang is an echo. From which surface has the sound reflected to cause this echo?

10.

A student claps once when standing away from a large wall. The speed of sound in air is . How long after clapping does the student hear an echo?

11.

A ship sends a pulse of sound vertically downwards to the sea bed and an echo is heard later. If the sea bed is deep, what is the speed of the sound in the water?

12.

A pulse of sound is produced at the bottom of a boat. The sound travels through the water and is reflected from the sea bed. The sound reaches the boat again after . The speed of sound in the water is .

How far below the bottom of the boat is the sea bed?

13.

A boy stands from a wall. He claps and when he hears the echo, he immediately claps again. He continues this for some time. Another student has a stop-watch. She starts the watch on the first clap and stops it on the eleventh clap. The watch reads 10.0s. Which value do her measurements give for the speed of sound in air?

14.

A pulse of sound is produced at the bottom of a boat. The sound travels through the water and is reflected from the sea-bed. The sound reaches the boat again after . The sea-bed is below the boat.

Using this information, what is the speed of sound in the water?

15.

A student stands a few hundred metres away from a wall and shouts. He hears a faint echo. Which statement is correct?

The sound waves returning are quiet because they have a reduced frequency.
The sound waves returning are quiet because they have a reduced wavelength.
The sound waves returning to the student are longitudinal.
The sound waves returning to the student are transverse.

16.

Which row gives the nature of sound waves and the name of the effect that causes an echo of a sound?

	nature of sound waves	effect causing an echo
A	longitudinal	reflection
B	longitudinal	refraction
C	transverse	reflection
D	transverse	refraction

17.

A student stands in front of a vertical, flat cliff and bangs together two pieces of wood to make a short, loud sound. A timer records the echo of the sound after the pieces of wood are banged together. Based on this result, what is the speed of sound?

18.

In an experiment to measure the speed of sound, a student uses a stopwatch to find the time taken for a sound wave to travel from point X to a vertical wall at point Y and back to point X to receive the echo of the sound. She does this six times.

The table below shows her results.

measurement	time (s)
first	1.0
second	1.4
third	1.2
fourth	0.8
fifth	1.8
sixth	1.0

Which value for the time should be used to calculate the speed of sound?

19.

Student 1 and student 2 stand apart as shown. Student 1 fires a starting pistol. Student 2 hears the sound twice, once by the direct route and once from the reflection from the wall.

The speed of sound in air is . What is the interval between hearing the two sounds?

20.

Some sound from a loudspeaker at P travels directly to Q. Sound also reaches Q after being reflected from a wall at R.

The speed of sound is . What is the difference in time for a sound to travel from P to Q by the two routes?