Sci ~ Ch.42 Sound Flashcards
Does sound need a medium to travel through? Can it travel through a vacuum?
Sound needs a medium but cannot travel through a vacuum.
What would happen if if there were no medium to travel through?
The sound wouldn’t be able to travel as there would be nothing to pass on the vibrations
What is the speed of sound in air?
340 m s^ -1
What is sound?
Sound is a form of energy which is caused by vibrations.
Sound travels faster in ________ materials.
Denser (faster in solids than in liquids and faster in liquids than in gases)
What evidence do we have that light travels faster than sound?
Thunder and lightning
Lightning flash travels at the speed of light.Thunder arrives a little later travelling at the speed of sound.
How do we calculate how far away the lightning is?
Measuring the time lag between the flash of lightning and the clap of thunder.Each second in this time lag represents a distance of 340m.
What are Echoes?
Echoes are sounds that are reflected from a surface.
What type of surfaces are best at reflecting sound?
Hard solid
Disadvantage of echoes?
Nuisance in large halls,cinemas and theatres.
Solution: soft padded walls & thick carpets are used to absorb unwanted echoes.Hence soft surfaces are bad reflectors or good absorbers of sound.
How are echoes used by ships?
Ships use echo-sounding or echo-location to find out the depth of the sea.
Speed of sound in water?
1500 m/s
Outer ear:
Shaped to collect sound.Directs the vibrating air particles to your eardrum.
Eardrum:
Like a thin drum skin.incoming sound makes it vibrate back and forth.
Inner ear
Vibrations are carried through the middle ear to the inner ear
