Physics Of Music Exam 1

Front 1

Amplitude, A

Back 1

the largest "distance" from equilibrium position for an object in periodic motion.

Front 2

Elasticity

Back 2

or Springyness. Serves to restore the particles back to their equilibrium positions.

**This restoring force is always directed toward the equilbrium position and is therefore characterized as a negative force (i.e. it is always points in the opposite direction to the particle's displacement).

Front 3

Equilibrium Position

Back 3

The position of an object when it is at rest. When set into oscillation, the
object will oscillate about this equilibrium position.

Front 4

Frequency, f

Back 4

Hz.

The number of cycles a periodic system executes in one second.

Front 5

Inertia

Back 5

That quality of a medium that \resists" being moved.

Front 6

Intensity, I

Back 6

W/m^2

The sound intensity is a measure of how much power a wave carries per unit area

Front 7

Longitudinal Wave

Back 7

A wave for which the particles of the medium move along a line parallel to the wave's direction of propagation through the medium. An example would be a sound wave, for which
the particles of the air move back and forth in the same direction as the wave's propagation.

Front 8

Loudness, L

Back 8

sones.

corresponds to the ears ability to discern different levels of loudness for a particular frequency.

Front 9

Loudness Level, LL

Back 9

phons.

1 phon = 1 db @ 1000Hz

a subjective measure of loudness as heard by the human ear. Tones of different frequency need to be set at different intensities in order for the ear to perceive them as having the same loudness level, owing to the non-linear frequency response of the ear.

Front 10

Medium

Back 10

Material through which a wave passes, such as air. A medium is necessary for the support of
wave propagation from one place to another. Two essential characteristics of any medium that supports wave propagation are Elasticity and Intertia.

Front 11

Natural Frequency

Back 11

Physical objects have an elastic character, so that when they undergo a sudden deformation, perhaps from being struck or bumped, they oscillate with definite frequencies characteristic
of the object itself.

Front 12

Period, T

Back 12

s (seconds)

The time it takes for a periodic system to complete one cycle of motion, measured in units of seconds.

Front 13

Periodic Motion

Back 13

A motion that repeats itself with the same pattern of motion, however complex it may be.

Front 14

Physics

Back 14

The study of matter and its interaction with energy.

Front 15

Principle of Inertia

Back 15

states that a body at rest tends to stay at rest, and a body in motion tends to stay in motion, unless acted on by an external force.

Front 16

Resonance

Back 16

A phenomenon that occurs when the frequency of a periodic force applied to an object
equals the natural frequency of the object. The result is large response from the object, such that a small force produces large amplitude response.

Front 17

Simple Harmonic Motion, SHM

Back 17

Motion that is described by a sinusoidal function, characterized by three attributes: 1) the motion takes place symmetrically about an equilibrium position, 2) the motion repeats itself in a definite time interval called the period, and 3) the speed of the oscillator varies through out the cycle in a regular fashion.

Front 18

Sound Level, SL

Back 18

db. (decibels)

a logarithmic representation of sound intensity, defined as 10log(I2/I1)

The absolute sound level is the value relative to the threshold of hearing, which has an intensity of 10^-12 Watts/cm^2

Front 19

Sound Waves

Back 19

Disturbances that move through a medium as zones of compression and rarefaction. Sound waves propagate through the air as logintudinal waves, for which the particles of the medium are forced into motion along the same direction as the wave's propagation.

Front 20

Superposition

Back 20

the process of adding two or more waves together to form one.

The superposition is found by adding the amplitudes of the
various waves together at any particular point along the x-axis.

Front 21

Transverse Wave

Back 21

A wave for which the particles of the medium move along a line perpendicular to the wave's direction of propagation through the medium. An example would be a wave on a guitar string, for which the particles of the string move up and down while the wave moves back and forth along the string.

Front 22

Wave

Back 22

A disturbance that propagates through a medium. Wave carries energy, and displace particles of the medium as they pass through.

Front 23

Diffraction

Back 23

Diffraction can be thought of
“bending” – a wave can diffract
around a corner and fill the
room.

Diffraction can occur when the
wavelength is comparable to the
size to the dimension of the
system, in this case, the width of
the “doorway”

Front 24

Reflection

Back 24

The law of reflection states
that the angle of reflection
equals the angle of incidence.

Reflection can occur when the
wavelength is small compared
with the dimensions of the
reflecting surface.

Front 25

Inverse-Square Law

Back 25

The Intensity of a sound wave decreases in proportion to 1/r^2, where r is the distance from the source.

*If r is doubled, the intensity decreases by 1/4.

Front 26

Range of hearing

Back 26

0-120 db