Year 8 Sound Flashcards
How is sound made ?
Vibrations / oscillation
What are some sources of vibration?
Vocal chords, the skin on a drum, strings on a cello, air inside/metal casing of a trumpet, the reed of an obo and the diaphragm of the speaker
What part of the ear vibrates?
Eardrum
How does sound travel from the source to our ears ?
Longitudinal sound waves
What is a longitudinal wave?
Longitudinal waves are waves in which the vibration of the medium is parallel to the direction the wave travels.
What happens to particles and air pressure when sound travel through the air?
They push and pull the air particles vibrate, left and right
What does compression mean?
It’s a region where the air pressure is higher than normal
What does rarefaction mean?
A region where the air pressure is lower than normal
Describe an experiment showing that sound travels as longitudinal waves.
The loudspeaker and candle demonstration.
The speaker is facing the candle and the speaker is turned on the candle will then flicker showing that longitudinal waves are present
Describe the Bell jar experiment
It shows if sound can travel through a vacuum.
It takes the air out from the jar, and a bell is inside a bit it keeps ringing, but as the particles are removed, there is nothing for the sound wave to travel through so you cannot hear the bell
What happens to sounds in a vacuum ?
Without Air particles, there can be no vibrations
Does sound travel faster through liquid solid or gas?
Solid because the denser the medium, the faster the sound travels
How do you measure the speed of sound?
S =d/t get two people far away from each other, and one person hits a block together. The other person sees them do this starts the stopwatch, and then when they hear the sound, they stop the stopwatch. 
What does Mach 1 mean ?
The sound waves cannot escape the noise of the jet
What happens when Mach 1 is exceeded ?
A sonic boom
