waves & sound part i - characteristics of waves learning goal sol ps 8 – the student will...

Waves & Sound

Part I - Characteristics of Waves

Learning Goal

SOL PS 8 – The student will investigate and understand characteristics of sound and technological applications of sound waves.

Essential Questions

What is a wave?

What are the measurable properties of waves?

How are wavelength, frequency, speed calculated?

A. What is a wave?

Wavesrhythmic disturbances that carry energy through

matter or space (Video Clip)

Mediummaterial through which a wave transfers energysolid, liquid, gas, or combinationelectromagnetic waves don’t need a medium

(e.g. visible light) Video Clip

A. What is a wave?

Two Types:

Longitudinal Transverse

A. What is a wave?

Transverse Wavesmedium moves

perpendicular to the direction of wave motion

A. What is a wave?

Longitudinal Waves (a.k.a. compressional)medium moves in the same direction as wave

motion

A. What is a wave?

Wave Anatomy

rarefaction

compression

wavelength

wavelength

Amount of compression corresponds to amount of energy AMPLITUDE.

B. What are the measurable parts of a

wave?

Your ideas?

B. What are the measurable properties of

wave? Simulation: Waves on a String Answer the following:

1) How does the amount that I wiggle the wrenchaffect the wave?

2) How does the speed that I wiggle affect the wave? 3) Switch to “Oscillate”:

» What happens when I change amplitude?» What happens when I change frequency? » What happens when I change damping? » Explain these three underlined words.

B. What are the measurable parts of a wave?

Wave Anatomycrests

troughswavelength

wavelength

amplitude

amplitude

corresponds to the amount of

energy carried by the wave

nodes

Frequency ( f )

# of waves passing a point in 1 second

Hertz (Hz)shorter wavelength

higher frequency higher energy

1 second

B. What are the measurable parts of a wave?

C. How are wave properties calculated?

Velocity ( v )speed of a wave as it moves forwarddepends on wave type and medium

v = × f v: velocity (m/s)

: wavelength (m)

f: frequency (Hz)

WORK:v = × f

v = (3.2 m)(0.60 Hz)

v = 1.92 m/s


EX: Find the velocity of a wave in a wave pool if its wavelength is 3.2 m and its frequency is 0.60 Hz.

GIVEN:

v = ?

= 3.2 m

f = 0.60 Hz

v

f

WORK: f = v ÷

f = (5000 m/s) ÷ (417 m)

f = 12 Hz


EX: An earthquake produces a wave that has a wavelength of 417 m and travels at 5000 m/s. What is its frequency?

GIVEN:

= 417 m

v = 5000 m/s

f = ?

v

f

D. How do waves behave?

Reflection occurs when a wave bounces

back after striking a barrier.


Refraction occurs when a wave bends as it passes from one medium to another.


Video Clip: Wave Interference

LET’S REVIEW! (copy into notes)

A wave is created when a source of ________ causes a vibration to move through a _________.

There are several types of mechanical waves including _____________ waves and ____________ waves.

Draw an example of each.

energymedium

transverselongitudinal


A _____________(compression) wave is a wave in which the vibration of the medium is ____________ to the direction in which the wave travels.

This type of wave consists of a repeating pattern of _____________ and _____________.

longitudinal

parallel

compressions rarefactions


All waves exhibit certain characteristics: __________, ___________, and ___________.

Draw a transverse wave and label the three things listed above.

Draw a longitudinal wave and label the three things listed above.

wavelength frequencyamplitude