2.5 Wave Motion And Sound Flashcards
What is a mechanical wave?
An oscillation of matter
Why is a mechanical wave an oscillation of matter?
It requires a medium through which to transmit energy
Why cant mechanical waves exist in a vacuum?
Because vacuums have no matter to transmit energy through
What are the two classifications of mechanical waves?
Transverse or longitudinal
How does a transverse wave travel along its wavelength?
Perpendicular to the direction of propagation of the wave (up and down like a normal wavelength)
How does a longitudinal wave travel along its wavelength?
The displacement is parallel to the propagation of the wave (being pushed horizontally)
What are the 4 parts to a transverse wave?
-wavelength
-amplitude
-crest (top)
-trough (bottom)
In a longitudinal wave what is it called when the particles are close together when traveling through?
Compression
In a longitudinal wave what is it called when the particles are spread apart and travel through the wave?
Rarefaction (sometimes called expansion)
What is one periodic time of a wavelength?
The time it takes to complete one oscillation
What is the frequency of a wavelength?
The number of complete oscillations in one second
What is the equation for wavelength?
Wave speed / frequency
What is wave interference?
The phenomenon that occurs when two waves meet and form a resultant wave greater, lower, or the same amplitude
What are standing/ stationary waves?
The combination of waves of the same amplitude and frequency moving in opposite directions casing a point where the wave doesn’t move at all
The phenomenon of standing/stationary waves is the result of?
Interference
What are sound waves?
Vibrations that travel through the air or another medium and can be detected when they reach an elastic medium, such as a microphone or eardrum
The speed at which sound waves travel depends on?
The medium that the waves are passing throgh
What is the speed of sound in a normal room?
343m/s
What is the speed of sound in water?
1500m/s
When temperature increase wha happens to the speed of sound?
It decreases
What is the equation to calculate the speed of sound?
20 x √temperature
What is a mach number describing?
The ratio of the speed of an aircraft in relation to the speed of sound
What is subsonic?
Less than mach 1
What is transonic?
Going mach 1
What is supersonic?
Greater than mach 1
What is hypersonic?
Faster than mach 5
What does the loudness of a sound depend on?
The amplitude of the vibrations and the distance from the sound source
At what level of noise causes permanent damage to human ear from a prolonged exposure?
Sound pressure levels exceeding 85dB
In relation to sound what is pitch?
A shrill (high pitched noise) sound can be distinguished from a deep sound
What does pitch depend on?
The frequency (the greater the frequency, the higher the pitch and vice versa)
When you have multiple sounds being produced what is the tone with the lowest frequency called?
Fundamental frequency
When you have multiple sounds playing what are the tones called if they aren’t the lowest frequency?
Overtones or harmonics
What is the Doppler effect?
The change in frequency of a wave, caused by the movement of a body relative to the wave source (think of an ambulance driving past and how the sound changes)
If the source of a sound moves towards you, what happens to the frequency of the sound?
It will appear higher and faster
If the source of a sound moves away from you, what happens to the frequency of the sound?
It appears lower and slower
