Final Exam Flashcards
Force (Inertial)
Force (inertial) = mass * acceleration
- newton’s second law of motion
- measured in Newtons
F=ma
Pressure
Pressure = Force/Area
- measured in Pascals or Newton/m^2
- 1 pascal = 1 Newton/m^2
P=F/a
Force (Stiffness)
Force (stiffness) = -k*displacement - stiffness is measured in kg/sec
- force of stiffness happening is measured in Newton
Work
Wok = force*displacement
- measured in Joules
Total (forcing force/driving force)
Total (or forcing force) = (Mass * acceleration) + (damping or resistance * velocity) + (k*displacement)
For sinusoids ONLY rms is?
rms of sinusoid = .707
How does natural frequency relate to mass and stiffness?
- natural frequency is directly proportional to square root of stiffness
- inversely proportional to square root of mass (directly proportional to 1/square root of mass)
What is the definition of angular velocity?
angular velocity = 2f
What is the wavelength in reference to speed and frequency of sound
(lambda) = s/f - speed of sound over frequency
- wavelength gets longer as frequency goes down, shorter as it goes up
Mass Reactance
Xm= 2(pi)fm
- frequency
- mass
Compliant/Stiffness Reactance
Xc=1/ [2(pi)fc]
- frequency
- compliance
Magnitude of Impedance
Z = Sq root [R2 + (Xm-Xc)2]
Law of exponents
Xa * Xb = Xa+b
Xa/Xb = Xa-b
Law of Logarithms
log (a*b) = log a + log b
log (a/b) = log a - log b
log ab = b log a
log 1/a = -log a
Log10 1
Log10 2
Log10 3
Log10 1 = 0.0
Log10 2 = 0.3
Log10 3 = 0.48
Decibels for ratio of intensities
dB = 10 log10 (Ix/Ir)
Decibels for ratio of presures
dB = 20log10 (Px/Pr)
Reference for intensity level (IL)
10-12 watt/m2
Reference for pressure level (SPL)
20*10-6 Pa = 20mu pascals
=.00002 Pa
Lps / Lpc
- amount of pressure or energy in 1 Hz band
Lps = SPLwb-10 log10 (change in)fwb
SPLnb
SPLnb = SPLwb-10log10 [(change in) fwb / (change in) f]
% of harmonic distortion
% harmonic distortion = 100 * [(V22 + V32 +… +Vn2)/V12]
Write a sentence using thefollowing words and phrases: “input signal” “output signal” loudspeaker” “electrical-to-mechanical transducer system” “voltage waveform” and “acoustic waveform”
What types of systems perform mechsnical to electrical transformations?
The cochlea.