Sound

Question 1

What kind of waves are sound waves?

Answer 1

Longitudinal waves

Question 2

Define a longitudinal wave.

Answer 2

A wave where the vibrations are in the same direction (parallel to) as the direction of travel.

Question 3

What is the label A on this longitudinal wave?

Answer 3

compressions.

Question 4

What is the label B on this longitudinal wave?

Answer 4

Rarefactions

Question 5

What is the label C on this longitudinal wave?

Answer 5

Wavelength

Question 6

How does a loudspeaker create sound waves?

Answer 6

Sound waves are produced by all vibrating objects. Loudspeakers work by converting electrical energy into the kinetic energy of a moving cone.

Question 7

What is an echo?

Answer 7

The reflection of a sound wave.

Question 8

What kind of surfaces are good at reflecting sounds?

Answer 8

Hard, smooth surfaces (eg. a wooden floor or a stone wall)

Question 9

What kind of materials are good at absorbing sounds?

Answer 9

Soft, rough surfaces (eg. foam, a pillow or carpet)

Question 10

What label is missing from the green box?

Answer 10

The ear drum

Question 11

What are the missing labels?

Answer 11

F - Peak
G - Amplitude
H - Trough
J - Wavelength

Question 12

What characteristic of a wave determines how loud a sound is?

Answer 12

Its amplitude

Question 13

The frequency is the number of waves per second. What happens to the spacing of the waves when we increase the frequency?

Answer 13

The waves will be closer together

Question 14

What does a sound waves frequency tell you about how the noise you will hear?

Answer 14

The pitch. High frequency = high pitch noise. Low frequency = low pitch noise

Question 15

Which two waves have the same wavelength?

Answer 15

B and D

Question 16

Which waves be as loud as A but be a lower pitch?

Answer 16

B

Question 17

How can loud noised damage your ears?

Answer 17

It can burst your ear drum

Question 18

What is the speed of sound in air?

Answer 18

Roughly 340 m/s

Question 19

Which does sound travel fastest though. Which does it travel slowest through?
Solids, liquids, gases?

Answer 19

Fastest - Solids
Slowest - Gases

Question 20

Why does sound travel faster in steel than in water?

Answer 20

The particles of liquids (water) are further apart than in a solid (steel). Sound waves move more slowly when particles are further apart.

Question 21

What is the unit of frequency?

Answer 21

Hz (hertz)

Question 22

What is the frequency range of human hearing?

Answer 22

Human beings can generally hear sounds as low as 20 Hz and as high as 20,000 Hz (20 kHz).

Question 23

Sound with a frequency of more than 20,000 Hz is called _______?

Answer 23

Ultrasound

Question 24

What is a use for ultrasound?

Answer 24

Ultrasound scans are a safe way to check on the health of unborn babies.

Question 25

Explain why a thicker string on a guitar will
have a lower pitch that a thinner string.

Answer 25

A thicker string will have a higher mass and not be able to vibrate as quickly. Fewer vibrations per second causes a lower pitch sound.

Question 26

How could you make a drum produce a louder sound? Explain this in terms of waves.

Answer 26

Hit it harder - this will create larger vibrations and a wave with a larger amplitude so it will be a louder sound.

Question 27

Sound travels in air because:

A
air particles stay still.

B
the wind blows it.

C
particles pass on vibrations.

D
electricity sends it through the air.

Answer 27

C

Question 28

What measurements and calcuations would you have to make to work out the speed of sound?

Answer 28

Time taken for echo to be heard.
Distance to wall.

Speed = 2x distance / time

*Careful that the sound needs to travel to the wall AND BACK for an echo to be heard.