Chapter 7- Waves And Sound Flashcards
What type of wave is sound?
Longitudinal wave
Transverse wave
Like people doing the wave in a stadium. Each person being a particle moving up and down (perpendicular)
Ex: electromagnetic waves
Transverse wave and energy
Particles oscillating perpendicular to the direction of energy transfer
Longitudinal waves and energy
Particles oscillate parallel to direction of energy transfer
Ex: sound waves
Speed of wave
v = f(wavelength)
Period of wave
T = 1/f
Angular frequency
Used in simple harmonic motion in springs and pendula
w= 2(pi)f = 2(pi)/T
Timbre
Quality of sound. Determined by natural frequency of the object
Audible frequency
Between 20 and 20,000 Hz
2 types of waves
- Transverse
2. Longitudinal
Speed of sound
Square root(B/density)
Doppler equation
Detector / source
Intensity
Pressure / Area
Sound level
B = 10 log(I/I*)
I*- 1 x 10^-12
Effects of dampening / attenuation
Same frequency (pitch), gradual loss of sound (smaller amplitude)
Wavelength of standing wave
2L/n
n- number of half-wavelengths supported by the string
Possible frequencies
f = nv/2L
Fundamental frequency
First harmonic. Lowest frequency (longest wavelength) of a standing wave that can be supported in a given string.
For strings attached at both ends how do you know which harmonic it is?
Number of antinodes
For open pipes how can you tell which harmonic it is?
Number of nodes present
Closed pipe equation for wavelength
4L/n
n- odd numbers only, quarter wavelengths
Frequency of standing wave in a closed pipe
nv/4L
Ultrasound machines calculate distance based on…
Travel time of the reflected sound
Pitch
Related to frequency
