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2010-06-24 17:17:02
Physics waves sound temperature

Midterm 2
Show Answers:

  1. In simple harmonic motion, what is the restoring force equal to?
  2. What is the period of oscillation for a mass m on the end of a massless spring?
    T=2pi sqrt(m/k)
  3. What is the general solution to Simple Harmonic motion?
    x = A cos(ωt)
  4. What is the angular frequency of a wave equal to?
    ω = 2πf = sqrt(k/m)
  5. What is the maximum speed of a simple harmonic oscillator?
    v = A sqrt(k/m)
  6. What is the velocity of a particle on a wave?
    The derivative of the displacement function
  7. What is the wavelength?
    lambda, the distance between two successive crests.
  8. What is the wave velocity?
    wavelength * frequency or wavelength / Period
  9. What is a transverse wave?
    Up down wave
  10. What is a longitudinal wave?
    Back and forth (Pressure) wave
  11. What I the wave velocity of a transverse wave on a cord under tension?
    v = sqrt(Force Tension/linear mass density)
  12. Define intensity (of a wave)
    The average power across unit area perpendicular to the direction of energy flow.
  13. What is the wave number k equal to?
  14. What is the principle of superposition?
    When two or more waves pass through the same region of space, the actual displacement is the vector sum of the separate displacements.
  15. What is Fourier’s Theorem?
    Any complete wave can be considered as being composed of many simple sinusoidal waves of different amplitudes, wavelength and frequencies.
  16. What is the velocity of sound in air at any Temperature?
    331 + .06T
  17. What is a Hertz?
    cycle per second
  18. What is the unit of intensity?
  19. A 30 dB sound has what level of intensity?
    10-9 (whisper)
  20. A noisy resturant is around how many dB?
    70db, intensity 1 x 10-5
  21. How many dB is a sound of 1 x 10-2 W/m2 intensity?
    100dB, siren at 30m
  22. What is the component unit of Watt?
    Joules / Second
  23. What does 'u' stand for?
    unified atomic mass units
  24. What is one u equal to?
    1.6605 x 10-27 kg
  25. What is beat frequency?
    The difference between two frequencies
  26. How do you find the distance traveled by a wave?
    distance equals velocity times time
  27. How to you express a percentage change?
    Delta over original
  28. What is Boltzmann's Constant used for?
    It represents R, the universal gas constant, divided by Avogadro's number.
  29. What is the value of Boltzmann's constant?
    1.38 x 10-23 J/K
  30. What is Avogadro's Hypothesis?
    Equal volumes of gas at the same pressure and temperature contain equal numbers of molecules.
  31. What is Avogadro's number Na?
    6.02 x 1023 mol-1
  32. What does R, the universal gas constant, represent?
    The constant of proportionality
  33. What is the value of R in SI units?
    8.314 J/mol * K
  34. What is the value of R in calories?
    1.99 calories / mol * K
  35. In PV = nRT what does the 'n' stand for?
    number of moles
  36. How do you convert from grams to moles?
    Mass of substance (grams) divided by molecular mass (grams / mole). Molecular mass is also know as atomic mass aka atomic weight
  37. In the ideal gas law PV = NkT, what does N stand for?
    number per mole times Avogadro's number
  38. How do you convert atm to pascals?
    multiply by 101325
  39. What are the four assumptions of an ideal gas?
    • 1. There are a large number of molecules of same mass moving in random directions at a variety of speeds
    • 2. The molecules are on average far apart from each other
    • 3. The molecules obey laws of classical mechanics
    • 4. Collisions are assumed to be perfectly elastic and brief
  40. How is Kinetic energy related to temperature?
    The average translational kinetic energy of molecules in random motion in an idea gas is directly proportional to the absolute temperature of the gas.
  41. What is root-mean-square velocity?
  42. What does the Maxwell distribution of speeds tell us about?
    The number of molecules at a certain velocity