lec 1 Flashcards
what is sound?
- vibration of a body in air (air = medium)
diff bw transverse wave and longitudinal wave?
- transverse: particles move perpendicular to wave direction.
- longitudinal: particles move in same direction as wave.
are sound waves transverse or longitudinal?
longitudinal
what is the velocity of sound at max displacement?
0 (swing example)
fill in the blanks: vocal cords store ___ energy.
when the vocal cords move, this energy is converted into ___ energy, producing vibrations that create sound waves.
- potential
- kinetic
define:
a) period
b) frequency
c) wavelength
a) period: time to complete a cycle of events (T).
b) frequency: number of cycles/second in Hz (1/T or c/lambda).
c) wavelength: distance in space covered by a complete cycle (c/f).
what is ācā in all these formulas?
- c = constant, speed of sound
- 343 metres/second OR 34,300 centimetres/second (unless otherwise stated)
the frequency of a sound is 1000Hz. how would you calculate the wavelength (lambda) with this info?
- lambda = c/f
- = 343 / 1000
- = 0.34m
the frequency of a sound is 1000Hz. how would you calculate the period (T) with this info?
- T = 1/f
- = 1/1000
- = 0.001sec (or 1msec)
where air molecules collide is called an area of ____.
where air molecules move apart is called an area of ____.
where molecules move through their preferred state is called an area of ___.
- compression
- rarefaction
- equilibrium
what is the pressure (relative to atmospheric pressure) during:
a) compression
b) rarefaction
c) equilibrium
a) pressure > atmospheric pressure
b) pressure < atmospheric pressure
c) pressure = atmospheric pressure
what is the term for the bending of a sound wave around obstacles?
diffraction
T or F: sound travels faster in solids and liquids than it does in air.
true!
what frequencies does a typical human ear detect?
20-20,000Hz
