fundamentals of sound

Card Set Information

Author:
CYNILISHUS
ID:
35736
Filename:
fundamentals of sound
Updated:
2010-09-19 19:29:25
Tags:
oscillation vibration
Folders:

Description:
week 1 oscillations and vibrations
Show Answers:

Home > Flashcards > Print Preview

The flashcards below were created by user CYNILISHUS on FreezingBlue Flashcards. What would you like to do?


  1. OSCILLATION
    ANY BACK AND FORTH MOVEMENT BETWEEN 2 STATES
  2. VIBRATION
    AN OSCILLATION THAT IS MECHANICAL, WITH ELASTICITY ACTING AS THE RESTING FORCE.
  3. PENDULUM
    COMMONLY USED AS A MODEL OF MOTION. MUST BE DISPLACED BY AN EXTERNAL FORCE IN ORDER FOR IT TO MOVE.
  4. SIDE NOTE:
    ALL OSCILLATIONS ARE NOT VIBRATIONS BUT ALL VIBRATIONS ARE OSCILLATIONS
  5. INERTIA
    RESISTANCE TO AN OBJECT TO CHANGE IT'S STATE OF MOTION.
  6. POTENTIAL AND KINETIC ENERY
    • HAS POTENTIAL ENERGY
    • KINETIC HAS TO DO WITH MOVEMENT OR MOTION DUE TO AN OBJECTS VELOCITY
  7. GRAVITY
    GIVES A PENDULUM POTENTIAL ENERGY
  8. DISPLACEMENT OF A PENDULUM
    • IS A VECTOR QUANITY THAT IS DESCRIBED BY ITS MAGNITUDE AND ITS DIRECTION.
    • DIRECTION: RIGHT IS POSITIVE
    • LEFT IS NEGATIVE
  9. SINUSOIDAL MOTION
    BACK AND FORTH MOTION OF A PENDULUM IS CALLED A SINUSOIDAL MOTION OR A SINE WAVE
  10. VELOCITY
    RATE OF CHANGE AND DISPLACEMENT
  11. ACCELERATION
    RATE OF CHANGE IN VELOCITY
  12. POSITIVE AND NEGATIVE ACCELERATION
    • POSITIVE: OBJECT IS ACCELERATING FROM THAT POINT TO THE POSITIVE DIRECTION
    • NEGATIVE: OBJECT IS ACCELERATING FROM THAT POINT TO THE NEGATIVE DIRECTION
  13. PERIODIC AND HARMONIC MOTION
    PERIODIC: MOTION THAT REPEATS ITSELF IN REGULAR INTERVALS UNTIL IT IS STOPPED BY EXTERNAL ACTION.

    HARMONIC: MOTION IN WHICH THE ACCELERATION OF THE OBJECT IS DIRECTLY PROPORTIONATE BUT OPPOSITE IN DIRECTION TO THE DISPLACEMENT OF THE OBJECT FROM ITS EQUILIBRIUM POSITION.
  14. MOTION OF A PENDULUM
    • SIMPLE HARMONIC MOTION OR SINUSOIDAL MOTIO OCCURS WHEN THE MOTIO OF A SINGLE OBJECT:
    • ***HAS AN ACCELERATION THAT IS DIRECTLY PROPORTIONAL BUT OPPOSITE IN DIRECTION TO THE DISPLACEMENT

    AND

    CHANGES IN DISPLACEMENT, VELOCITY, AND ACCELERATION ARE SINUSOIDAL FUNCTIONS OF TIME.
  15. WAVEFORM
    A FUNCTION REPRESENTING CHANGES IN PHYSICAL QUANTITY AS A FUNCTION OF TIME.
  16. FREQUENCY (f)
    • FREQUENCY = NUMBER OF CYCLES PER SECOND
    • (f)
    • MEASURED IN HERTZ (HZ) OR CYCLES PER SECOND (CPS)
    • 1 CYCLE/SECOND = 1 HZ
  17. CYCLE
    ONE FULL REPETITION OF MOTION
  18. PERIOD (T)
    • TIME REQUIRED TO COMPLETE ONE CYCLE (T)
    • REPORTED IN A TIME UNIT SUCH AS SECONDS (S)
    • MILLISECONDS (MS) OR MICROSECONDS (μs)
    • *INVERSE RELATIONSHIP BETWEEN FREQUENCY (F) AND PERIOD (T)
  19. FORMULAS
    #CYCLES/SECONDS = FREQUENCY

    TIME/# OF CYCLES=PERIOD
  20. EXAMPLES
    1.FREQUENCY = 4000 HZ THEN PERIOD = ?
    2. PERIOD = 2MS THEN FREQUENCY = ?
    3. FREQUENCY = 40 HZ THEN PERIOD = ?
    4. PERIOD = 1000 MS THEN FREQUENCY =?
    • 1. (T) = .00025
    • 2. (F) = 1/.002 = 500
    • 3. (T) =1/40 = .025
    • 4. (F) 1/1= 1HZ

    EXTRA NOTE: 1MS=.001
  21. PHASE (PHASE ANGLE)
    • phase angle between twowaves is a measure of their difference in phase.
    • Two wavesof the same frequency that are perfectly in phase have phaseangle zero;
    • if one wave is ahead of the other by a quartercycle, its phase angle 90 degrees (π/2 radians);
    • waves thatare perfectly out of phase have phase angle 180 degrees (πradians), and so on.
  22. IN PHASE
    OUT OF PHASE
    • IN PHASE- HAVE SAME STARTING POINT ON WAVEFORM
    • OUT OF PHASE HAVE DIFFERENT STARTING POINT ON WAVEFORM
  23. PHASE DIFFERENCE OR PHASE OFFSET
    • MAXIMUM POSSIBLE VALUE IS 180
    • CAN BE DETERMINED BASED ON ANY TIME POINT
    • REPORTED AS A POSITIVE NUMBER
    • PHASE DIFF ALWAYS POSITIVE
  24. PHASE SHIFT
    • CAN BE POSITIVE OR NEGATIVE
    • DIRECTION DEPENDS ON WHICH WAVEFORM IS DESIGNATED AS THE PRIMARY
    • AND WHICH AS THE SECONDARY
    • ENTIRE HISTORY OF WAVEFORM MUST BE CONSIDERED
  25. IF 2 SINE WAVES HAVE DIFFERENT FREQUENCIES YOU CAN DESCRIBE THE PHASE RELATIONSHIP IF
    • HIGHER FREQUENCY IS AN INTEGER MULTIPLE OF THE LOWER FREQUENCY...EX: 200HZ AND 400HZ
    • DETERMINE THE PHASE RELATIONSHIP BY LOOKING AT THE PHASES OF WAVEFORMS AT THE BEGINNING OF ANY CYCLE OF THE LOWER FREQUENCY WAVEFORM.
  26. IF 2 SINE WAVES HAVE DIFFERENT FREQUENCIES YOU CANNOT DESCRIBE THE PHASE RELATIONSHIP IF
    • HIGHER FREQUENCY IS NOT AN INTEGER MULTIPLE OF THE LOWER FREQUENCY
    • EX: 135HZ AND 600 HZ
  27. MAGNITUDE AND INSTANTANEOUS MAGNITUDE
    • MUST INCLUDE A UNIT OF MEASUREMENT EX: 20M OR 400
    • CAN BE CONSTANT OR VARY IN TIME

    • INSTANTANEOUS MAGNITUDE
    • MAGNITUDE OBSERVED AT ANY GIVEN MOMENT IN TIME
  28. AMPLITUDE
    AMPLITUDE IS MAGNITUDE OF A PERIODIC WAVEFORM MAXIMUM OR PEAK
  29. PEAK TO PEAK MAGNITUDE OR PEAK TO PEAK VALUE
    P2P
    IN SIMPLE HARMONIC MOTION, PEAK TO PEAK MAGNITUDE IS TWICE AS LARGE AS THE WAVEFORM AMPLITUDE.

    IF THE WAVEFORM IS NOT SYMMETRICAL, IT MAY HAVE DIFFERENT POSITIVE (+) AND NEGATIVE (-) VALUES, AND THE P2P VALUE IS DIFFERENT BETWEEN BOTH AMPLITUDES.
  30. AVERAGE MAGNITUDE (Aavr)
    AVERAGE ANY SIMPLE HARMONIC WAVEFORM WILL ALWAYS BE 0.
  31. UNIPOLAR OR RECTIFIED AVERAGE MAGNITUDE (Aua)
    TAKE NEGATIVE PART OF CYCLE AND FLIP IT UP.

    Aua=2A/PIE

    SEE EXAMPLE PAGE 15 ON HAND OUT 8/31/10
  32. ROOT MEAN SQUARE OR RMS
    • ROOT MEAN SQUARE (RMS) AMPLITUDE (Ams)
    • THE CONSTANT MAGNITUDE (ONE VALUE) THAT WOULD PRODUCE THE SAME POWER AS THE ORIGINAL QUANTITY OF THE WAVEFORM (MAGNITUDE THAT VARIES)

    Arms=A/√2=Ax0.707
  33. MASS AND SPRING SYSTEM
    • A MODEL USED TO STUDY PHENOMENA ASSOCIATED WITH SIMPLE HARMONIC MOTION INCLUDING:
    • MASS
    • STIFFNESS
    • AND FRICTION EFFECTS
  34. MASS
    • AMOUNT OF MATTER
    • A MASS WILL VIBRATE BACK AND FORTH IN A SIMPLE HARMONIC MOTION BECAUSE OF INTERACTION
    • BETWEEN FORCE OF ELASTICITY AND
    • FORCE OF INERTIA
  35. STIFFNESS
    MECHANIC PROPERTIES OF ELASTIC BODY THAT DESCRIBES ITS OPPOSITION TO CHANGE IN DIMENSION ALSO INVERSE OF COMPLIANCE
  36. FRICTION
    FORCE OPPOSES RELATIVE MOTION OF A BODY THAT IS IN CONTACT WITH OTHER BODIES
  37. PENDULUM AND MASS AND SPRING
    • PENDULUM
    • *INITIAL DISPLACEMENT IS DETERMINED BY HOW FAR THE PENDULUM IS PULLED AWAY BY AN EXTERNAL FORCE. EX THE AMOUNT OF FORCE APPLIED TO THE SYSTEM

    • MASS AND SPRING
    • *INITIAL AMPLITUDE IS DETERMINED BY THE FORCE THAT IS APPLIED TO THE MASS
  38. HOOKE'S LAW OF ELASTICITY
    STATES THE FORCE PRODUCED BY AN ELASTIC OBJECT IS LINEARLY PROPORTIONAL TO IT'S EXTENSION.

    IF A SPRING IS EXTENDED, THE FORCE OF ELASTICITY WORKS AGAINST THE EXTENSION.

    IF THE SPRING IS COMPRESSED, THE FORCE OF ELASTICITY WORKS AGAINST THE COMPRESSION.

    THE FARTHER AWAY THE SPRING IS STRETCHED OR COMPRESSED, THE GREATER THE FORCE OF ELASTICITY.
  39. HOOKE'S LAW OF ELASTICITY CONT...
    AS THE OBJECT MOVES CLOSER TO ITS EQUILIBRIUM POSITION, THE EFFECT OF THE FORCE ELASTICITY DECREASE, BUT THE OBJECT MAXIMUM VELOCITY BECAUSE OF THE FORCE OF INTERTIA. OR INCREASES VELOCITY.

    WHEN THE SPRING REACHES EQUILIBRIUM THE FORCE OF ELASTICITY IS EQUAL TO ZERO, BUT THE MASS MOVES FURTHER DUE TO THE FORCE OF INERTIA (Fm)

    INTERACTION BETWEEN THE FORCES OF ELASTICITY AND INTERTIA DETERMINES THE FREQUENCY OF THE BACK AND FORTH MOVEMENT OF THE VIBRATING SYSTEM (THE RESONANCE FREQUENCY).
  40. RESONANCE AND FREE VIBRATION
    • FREE VIBRATION
    • DEFINED AS THE BACK AND FORTH VIBRATION OF A SYSTEM ONCE ITS INITIALLY SET INTO MOTION.

    • RESONANCE FREQUENCY (Fr)
    • DEFINED AS THE FREQUENCY OF FREE VIBRATION.
    • SIMPLE VIBRATING SYSTEMS HAVE ONE RESONANCE FREQUENCY.
    • COMPLEX VIBRATING SYSTEMS MAY HAVE SEVERAL RESONANCE FREQUENCIES.
  41. RESONANCE FREQUENCY....
    • IS DETERMINED BY THE MASS, STIFFNESS AND FRICTION OF THE SYSTEM
    • *IS THE FREQUENCY AT WHICH A SYSTEM SET INTO FORCED VIBRATION WILL VIBRATE WITH ITS GREATEST MAGNITUDE

    • FORCED VIBRATION
    • *VIBRATION IN WHICH A SYSTEM IS FORCED TO VIBRATE BY A CONTINUOUSLY OR PERIODICALLY APPLIED EXTERNAL FORCE.
  42. RESONANCE AND FREE VIBRATION
    THE RESONANCE FREQUENCY FOR A MASS AND SPRING SYSTEM DEPENDS ON THE STIFFNESS OF THE SPRING AND THE AMOUNT OF MASS.

    LARGE OR LOOSE MASS WILL HAVE LOWER RESONANCE FREQUENCY

    SMALLER MASS OR STIFFER WILL HAVE HIGHER RESONANCE FREQUENCY.
  43. FRICTION AND DAMPED VIBRATION
    *BOTH THE PENDULUM AND THE MASS AND SPRING SYSTEM STOP MOVING BECAUSE OF FRICTION.

    *FRICTION RESULTS IN THE TRANSFER OF ENERGY FROM KINETIC ENERFY TO THERMAL ENERGY (HEAT)

    • *MASS AND SPRING SYSTEM
    • FRICTION IS CAUSED BY THE RUBBING OF PARTS OF THE VIBRATING SYSTEM AGAINST SURROUNDING SURFACES AND AIR PARTICLES.
  44. FRICTION AND DAMPED VIBRATION CONT
    THE EFFECT OF FRICTION ON A VIBRATING SYSTEM IS CALLED DAMPING, AND THE RESULTING VIBRATION IS CALLED DAMPED VIBRATION.

    IF THERE IS NO FRICTION, THE WAVEFORM MAINTAINS THE SAME AMPLITUDE OVERTIME.

    • A SYSTEM IS MINIMALLY DAMPED (OR UNDERDAMPED) IF THERE IS VERY LITTLE FRICTION IN THE SYSTEM.
    • DAMPING WILL STILL MAINTAIN SAME FREQUENCY.

    TEMPORAL ENVELOPE IS A GRADUAL DECREASE.
  45. FRICTION AND DAMPED VIBRATION CONT
    A SYSTEM IS SAID TO BE HEAVILY DAMPED (OR OVERDAMPED) IF THERE IS A LOT OF FRICTION IN THE SYSTEM.

    *HEAVILY DAMPED HAS MORE FRICTION...NO OSCILLATIONS DUE TO TOO MUCH FRICTION.
  46. CRITICALLY DAMPED
    • A SYSTEM IS SAID TO BE CRITICALLY DAMPED IF THE OBJECT WILL MAKE ONLY ONE VIBRATION AND THEN RETURN TO IT'S NATURAL POSITION AS FAST AS POSSIBLE.
    • CRITICALLY DAMPED CUTS OFF THE VIBRATION EVEN FASTER AND THEN DOESNT DO ANYTHING ELSE.
  47. VIBRATION PERIODS
    • RISE TIME (GROWTH TIME OR ATTACK TIME)
    • TIME NEEDED FOR A WAVEFORM TO CHANGE FROM 10% TO 90% OF ITS PEAK VALUE (FULL AMPLITUDE)

    STEADY-STATE TIME (SUSTAIN TIME)

    FALL TIME (DECAY TIME, ROLL-OFF TIME)

    TIME NEEDED FOR A WAVEFORM TO CHANGE FROM 90% TO 10% OF ITS PEAK VALUE (FULL AMPLITUDE)
  48. FORCED VIBRATION
    OCCURS IF A SYSTEM IS NOT ALLOWED TO VIBRATE FREELY BUT INSTEAD IS FORCED TO VIBRATE BY A CONTINUOUS AND PERIODIC DRIVING FORCE.

    DRIVING FREQUENCY-FREQUENCY OF THE EXTERNAL DRIVING FORCE

    IN A FORCED MODE OF VIBRATION, THE SYSTEM WILL VIBRATE BACK AND FORTH AT THE FREQUENCY OF THE DRIVING FORCE.

    START SOMETHING IN VIBRATION AND KEEP FORCING IT TO VIBRATE IN ANOTHER FREQUENCY "DRIVING FORCE"
  49. FORCED VIBRATION
    • THE MAGNITUDE OF VIBRATION DEPENDS ON THE:
    • *MAGNITUDE OF THE APPLIED FORCE
    • *FREQUENCY OF THE DRIVING FORCE
    • *RESONANCE FREQUENCY OF THE SYSTEM BEING FORCED TO VIBRATE
    • *FRICTION IN THE VIBRATING SYSTEM

    ***IF A SYSTEM IS FORCED TO VIBRATE CLOSE TO OR AT ITS RESONANCE FREQUENCY, THE SYSTEM WILL VIBRATE WITH A GREATER MAGNITUDE THAN IF THE SAME SYSTEM IS FORCED TO VIBRATE AT A FREQUENCY THAT IS MUCH LOWER OR MUCH HIGHER THAN THE RESONANCE FREQUENCY.

What would you like to do?

Home > Flashcards > Print Preview