a wave

is a rhythmic disturbance that

carries/transfers energy through

matter or space

A repeating movement

Mechanical Waves

require a medium

medium: the matter through which a wave travels examples: water, air, anything made of matter

waves transfer energy from one point to

another with little or no permanent

displacement to the particles in the medium

Molecules pass energy along to neighbor,

who then passes energy to neighbor, etc.

All waves are produced by VIBRATIONS

Two Types of Mechanical

Waves:

1. Transverse Waves

2. Longitudinal/Compressional

Waves

Transverse Waves

waves that propagate (or move) perpendicular to the

direction of travel

crest

the point on the medium that exhibits the

maximum amount of positive or upward

displacement from the rest position

trough

the point on the medium that exhibits the maximum

amount of negative or downward displacement from

the rest position

amplitude

the maximum displacement of a particle on the medium

from its equilibrium position

wavelength

the length of one wave is measured

from a point on one wave to the same

point on the next wave

trough to trough

crest to crest

midpoint to midpoint

Anatomy of a Transverse Wave

Label the following parts of a transverse wave in your

notes:

equilibrium

crest

trough

amplitude

wavelength

Longitudinal Waves

waves that propagate (or move) parallel to the direction

of motion

compression

a point on a medium through which a longitudinal wave

is traveling that has the maximum density

rarefaction

a point on a medium through which a longitudinal wave

is traveling that has the minimum density

Anatomy of a Longitudinal Wave

Label the following parts of a

longitudinal wave in your notes:

compression

rarefaction

wavelength

Describing a Wave & Wave Speed

Frequency (f): the number of vibrations an object

makes in a unit of time (generally one second)

the unit of frequency is Hz = 1

𝑠

𝑓 =𝑣𝑖𝑏

𝑡

Period (T): the time needed to complete one vibration

(measured in seconds)

𝑇 =𝑡

𝑣𝑖𝑏

The Sears Tower sways back and forth at

a frequency of about .1 Hz.

What is the period of vibration?

Speed Review

an object’s speed is described by the distance traveled

in a specific amount of time (generally measured in

m/s)

Wave Speed

v = λ ● f

wave speed = wavelength ● frequency

Lambda