Physics Unit 4 -Sound and Waves B. Flashcards
Fixed End Reflection
Wave pulses
Wave pulses relfecting from a fixed end reflect INVERTED with the SAME amplitude
Free End Reflection
Wave pulses reflecting from a free end reflect UNCHANGED with SAME amplitude
2 Rules when moving wave pulse from one substance to another
- Some energy from original wave pulse is TRANSMITTED
- Some energy from original wave pulse is REFLECTED
What does the amount and type of reflection depend on (When going from one substance to another?)
Difference in density
When a wave pulse is going from a Faster to a Slower medium (Low -> High) how do the reflected and transmitted pulses change?
Reflected: Inverted w/ smaller amplitude
Transmitted: unaffected, reduced amplitude
When a wave pulse is moving from a fast to slow medium, why the amplitude reduced?
b/c in a dense medium, it is difficult for particles to move to more dense mediums
Wave Intereference
Two waves meet at a particular point and interfere with each other
Principle of superposition
Individual amplitudes added together to form a resultant wave
What happens after a resultant wave is made?
Waves just past through, undisturbed
Constructive intereference
two crests/ two troughs that meet amplifying each other (Made into one BIG wave)
Destructive Intereference
Crests and troughs of the same amplitude meet and dimish each other creating a node
node
point of zero amplitude (waves cancel each other out)
Sound is a __________________ wave made by regular _______________ and ______________ of matter
longitudinal; compression; rarefraction
Sound particles of medium ____________ but DO NOT _________ with wave energy
vibrate ; travel
Sound waves travels __________ from _________.
AWAY; source
SOunds waves are represented as ______________ waves of air _________
transverse; pressure
Sound waves must travel through a __________ in order to transmit sound
medium
Pitch is the ______________ of sound
frequency
Loudness is the __________________ of sound waves
amplitude
Quality is the __________________ of sound waves
complexity
Most efficient way of transfering sound is through a ? Why?
Solid; particles are close
IMF bonds act as a spring and sound transfers more efficiently
As temperature rises, what happens to the molecules which affect the speed of sound?
Molecules move faster, allowing waves to be transmitted faster
Explain how a Sonic Bomb is made
Sound pressure waves are left behind = cone shaped shock wave. There is a sudden pressure on the edge of the shock wave emitting a SONIC BOMB that is heard on the ground
Mach < 1
Subsonic speed
Mach =1
Speed of Sound
Mach > 1
Supersonic Speed
Doppler Effect
When soure moves, the frequency of it approaching is heard higher than the frquency of the source leaving
Approaching = -
Leaving = +
Standing Waves
produced by interference of 2 waves with the same frequency and wavelength moving in opposite directions
What happens when a tube has the same length, but a different frequency?
The next standing wave pattern will be present when frequency is changed
Trumpet has what kind of standing wave?
Open-end air column
Clarinet has what kind of standing wave?
closed-end air column
How does the rich note of wind intruements happen?
Due to the superposition of different harmonics
Mechanical Resonance and examples
A vibrating object gradually transfering energy to another object when the natural frequency of the second object matches the vibrational frequency of the original vibrating object. (Lithotripsy, breaking glass with voice)
Damping
The reduction of the amplitude of a vibration due to the energy absorption or destructive intereference
20Hz >
Infrasonic
20Hz-20 000Hz
Audible
20 000Hz <
Ultrasonic
Explain Active Sound Cancellation
Microphone detects unwanted sound, device creates a inverted wave with the same amplitude
inverted wave destructively interferes with the original wave creating a continous node
