Sound

Question 1

Describe a method to directly measure the speed of sound

Answer 1

1. Two people are needed, one handling a stopwatch and the other a pistol.
2. They should stand 100m away from each other. The distance between them can be measured with a trundle wheel.
3. The one holding the pistol should fire it.
4. The second person should start the stopwatch when they see the smoke and stop it when they hear the sound.
5. Steps 3 and 4 should be repeated several times to get an average time.
6. The speed can be found by using this equation: speed= distance travelled / time taken

Question 2

Describe a method to find the speed of sound using echoes

Answer 2

1. Two students should stand 50m away from a wall.
2. This distance can be measured with a trundle wheel
3. One holds two wooden blocks and the other a stopwatch.
4. The wooden blocks should be banged together at a regular rate until the bang and the previous echo coincide.
5. The second student should then measure the time for 20 bangs.
6. Divide this time by 20 to find the average time for 1 bang,
7. The distance between the students and the wall should be multiplied by two.
8. The equation speed = distance travelled / time should be used to find the speed

Question 3

What is the average speed of sound in solids?

Answer 3

2000 m/s

Question 4

What is the average speed of sound in liquids?

Answer 4

1500 m/s

Question 5

What is the average speed of sound in gases?

Answer 5

330 m/s

Question 6

An oscilloscope is…

Answer 6

A device used to represent sound waves

Question 7

What is the period?

Answer 7

The time, in seconds, for one complete oscillation

Question 8

Frequency is…

Answer 8

The number of complete oscillations/vibrations made in one second. Its unit is Hertz (Hz)

Question 9

Relationship between period and frequency?

Answer 9

T = 1/F

F = 1/T

F x T = 1

Question 10

What is amplitude?

Answer 10

The maximum or minimum displacement of the sound wave from the resting point/equilibrium

It is the meaure of the loudness of sound

SI unit is metres

Question 11

What is pitch?

Answer 11

How high or low a sound is

Question 12

What is th relationship between frequency and pitch?

Answer 12

The higher the pitch, the higher the frequency

The lower the pitch, the lower the frequency

Question 13

Frequency is high when…

Answer 13

When the crests are close together

Question 14

What is the human hearing range?

Answer 14

20Hz - 20,000 Hz

Question 15

What is ultrasound?

Answer 15

Sound above 20,000 Hz

Question 16

What is infrasound?

Answer 16

Sound below 20 Hz

Question 17

The compression is…

Answer 17

The area of the sound wave where molecules are close to each other and there is a high pressure

Question 18

The rarefaction is…

Answer 18

The area of the sound wave where molecules are spread out and there is a low pressure

Question 19

Formula for calculating the speed of sound waves?

Answer 19

Speed = wavelength x frequency