Sound Flashcards
What kind of waves are sound waves?
Longitudinal waves
Define a longitudinal wave.
A wave where the vibrations are in the same direction (parallel to) as the direction of travel.
What is the label A on this longitudinal wave?
compressions.
What is the label B on this longitudinal wave?
Rarefactions
What is the label C on this longitudinal wave?
Wavelength
How does a loudspeaker create sound waves?
Sound waves are produced by all vibrating objects. Loudspeakers work by converting electrical energy into the kinetic energy of a moving cone.
What is an echo?
The reflection of a sound wave.
What kind of surfaces are good at reflecting sounds?
Hard, smooth surfaces (eg. a wooden floor or a stone wall)
What kind of materials are good at absorbing sounds?
Soft, rough surfaces (eg. foam, a pillow or carpet)
What label is missing from the green box?
The ear drum
What are the missing labels?
F - Peak
G - Amplitude
H - Trough
J - Wavelength
What characteristic of a wave determines how loud a sound is?
Its amplitude
The frequency is the number of waves per second. What happens to the spacing of the waves when we increase the frequency?
The waves will be closer together
What does a sound waves frequency tell you about how the noise you will hear?
The pitch. High frequency = high pitch noise. Low frequency = low pitch noise
Which two waves have the same wavelength?
B and D
Which waves be as loud as A but be a lower pitch?
B
How can loud noised damage your ears?
It can burst your ear drum
What is the speed of sound in air?
Roughly 340 m/s
Which does sound travel fastest though. Which does it travel slowest through?
Solids, liquids, gases?
Fastest - Solids
Slowest - Gases
Why does sound travel faster in steel than in water?
The particles of liquids (water) are further apart than in a solid (steel). Sound waves move more slowly when particles are further apart.
What is the unit of frequency?
Hz (hertz)
What is the frequency range of human hearing?
Human beings can generally hear sounds as low as 20 Hz and as high as 20,000 Hz (20 kHz).
Sound with a frequency of more than 20,000 Hz is called _______?
Ultrasound
What is a use for ultrasound?
Ultrasound scans are a safe way to check on the health of unborn babies.
Explain why a thicker string on a guitar will
have a lower pitch that a thinner string.
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.
How could you make a drum produce a louder sound? Explain this in terms of waves.
Hit it harder - this will create larger vibrations and a wave with a larger amplitude so it will be a louder sound.
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.
C
What measurements and calcuations would you have to make to work out the speed of sound?
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.
