The Nature of Sound Flashcards
(27 cards)
what is sound?
a disturbance that results from any kind of movement, which creates changes in pressure in a medium.
these pressure changes are propagated through the medium to the ear
what is air?
air is a gas made of molecules of various chemicals.
what is brownian motion?
the random movement of molecules which causes them to collide.
molecules are never stationary except at absolute zero
molecular collisions produce…
pressure!
what is pressure?
the force acting perpendicularly on surface
force/area=pressure
greater area, less pressure
less area, more pressure
english system measurements of pressure
pounds/square inch
SI measurement of pressure (MKS)
force= Newtons area= meters
pressure= N/meters squared = 1 pascal
SI measurement of pressure (CGS)
force= dynes area= centimeters
pressure= dynes/centimeters squared= 1 microbar
how do you measure air pressure?
displacement of liquid in a U-tube
how do you measure atmospheric pressure?
barometer!
Patmos is approx. 14.5 PSI or 100kPa
what is aerodynamics?
the movement of air
what is the most important constant about pressure of airflow?
it ALWAYS equalizes and moves from areas of HIGH to LOW pressure
this is different than brownian motion, although brownian motion is still occurring
what is driving pressure?
the difference in pressure causing air to flow, only present when there is a pressure differential
how is airflow measured?
liters or milliliters
what is airflow?
organized movement of air through a particular area in a specific interval of time
what is laminar flow?
parallel molecular motion, smooth flow, equal speed (calm river)
what is turbulent flow?
obstructed, disturbed flow with random variations of pressure (river with rocks and trees)
what is Boyle’s Law?
the inverse relationship between air volume and pressure
as volume increases, pressure decreases (VICE VERSA)
this allows for more area for the molecules to move around=less pressure generated
how are density and pressure related?
density and pressure are directly proportional
the higher the density, the higher the pressure
(more tightly packed, more collision, more pressure?
What is another name of relatively constant pressure?
ambient pressure
Compression
areas of high pressure (when molecule A knocks into molecule B, density increases and pressure increases)
Rarefaction
areas of low pressure ( A returns to its spot an keeps moving until elasticity pulls is back)
elasticity
the property of an object to be able to spring back to its original size/form/location/shape after bring stretched/detached/displaced
inertia
keeps an object stays in motion or at rest unless acted upon by an outside force
