apply
the
Doppler Effect
to
both sound and light waves.
explain
why a super sonic object
creates a
shock wave
and when a
sonic boom
is heard.
illustrate
the waves created by
an object that is traveling:
subsonic
,
sonic
,
supersonic
and
hypersonic
.
I can . . .
describe
the effect of relative motion
http://www.kettering.edu/~drussell/Demos/doppler/doppler.html
Stationary Source and Stationary Observers
Each person receives the same
number of waves per second.
http://www.kettering.edu/~drussell/Demos/doppler/doppler.html
Stationary Source but Moving Observer
The man receives MORE waves per second.
(He hears a higher frequency)
Stationary
Source
?
Object Moving
http://www.kettering.edu/~drussell/Demos/doppler/doppler.html
Race
Car
Moving Source but Stationary Observer
The man receives MORE waves per second.
(He hears a higher frequency)
Doppler Effect
Stretched and Wide
Compressed and Crunched
f´ = f v + v
o
v - v
s
f´ = new frequency (Hz)
f = original frequency (Hz)
v = velocity of the wave (m/s)
v
0
= velocity of the observer (m/s)
f´ = new frequency (Hz)
f = original frequency (Hz)
v = velocity of the wave (m/s)
v
0
= velocity of the observer (m/s)
?
256 Hz
343m/s
50 m/s
= 256
343
+
50
343
=
293
Hz
= 256
343
-
50
343
=
219
Hz
Toward Object
Away From Object
f´ = f
v + v
o
How many of you have been the “victim” of this equation?
http://www.easyreadernews.com/wp-content/uploads/2010/03/Best-Speed-Trap-480x368.jpg
f´ = f
v + v
o
f´ = f
v + v
o
General Formula for Doppler Effect
Definition of terms:
f
0
= observed frequency
f
s
= frequency of source
V = velocity of sound
v
0
= velocity of observer
v
s
= velocity of source
Example 4: A boy on a bicycle moves north at
10 m/s
.
Following the boy is a truck traveling north at
30 m/s
.
The truck’s horn blows at a frequency of
500 Hz
.
What is the apparent frequency heard by the boy?
Assume sound travels at
340 m/s
.
30 m/s
10 m/s
V = 340 m/s
f
s
= 500 Hz
The truck is approaching; the boy is fleeing. Thus:
v
s
= +30 m/s
v
s
= +
30 m/s
v
0
= -10 m/s
v
0
=
-10 m/s
f
0
= 532 Hz
f
0
=
532 Hz
0
0
s
s
V v
f
f
V v
0
0
340 m/s ( 10 m/s)
500 Hz
340 m/s - (30 m/s)
Example 4: A boy on a bicycle moves south at
10 m/s
.
Following the boy is a truck traveling north at
30 m/s
.
The truck’s horn blows at a frequency of
500 Hz
.
What is the apparent frequency heard by the boy?
Assume sound travels at
340 m/s
.
30 m/s
10 m/s
V = 340 m/s
f
s
= 500 Hz
The truck is approaching; the boy is fleeing. Thus:
v
s
= +30 m/s
v
s
= +
30 m/s
v
0
= +10 m/s
v
0
=
+10 m/s
f
0
= 565 Hz
f
0
=
565 Hz
+
0
0
s
s
V v
f
f
V v
0
0
340 m/s ( 10 m/s)
500 Hz
340 m/s - (30 m/s)
http://kfty.com/weather/interactive/
http://www.math.tau.ac.il/~turkel/B2.jpg
Complete
Visible Spectrum
Doppler Effect with Light
Absorption Spectrum
http://annwn.tempwebpage.com/cookpot/bits/neon.jpg
Sodium
Bromine
Deuterium
Helium
Hydrogen
Krypton
Mercury
Neon
Water Vapor
Xenon
Emission Spectrum
Doppler Effect with Light
Red Shift (Moving Away)
f´ = f
v ± v
o
Emission Spectrum
Doppler Effect with Light
Blue Shift (Moving Toward)
f´ = f
v ± v
o
Earth
Low
Frequency
High
Frequency
Hubble’s Law
(November 20, 1889 – September 28, 1953)
?
Stationary
Source
Object Moving
Sub
sonic
Object Moving
October 14 1947
Chuck Yeager – October 14, 1947
http://resources.schoolscience.co.uk/ICI/11-14/materials/match1pg2.html
?
Stationary
Source
Object Moving
Sub
sonic
Object Moving
Sonic
Object Moving
http://www.kettering.edu/~drussell/Demos/doppler/doppler.html
Source Moving FASTER than the waves it is making.
Ernst Mach
(1838–1916)
Cherenkov Radiation
Cherenkov Radiation occurs when
high energy particles are moving
http://wblrd.sk.ca/~mathc30/unit5/lesson0.htm
http://www.af.mil/photos/factsheet_photos.asp?fsID=126
Which object is traveling faster?
Sonic
Boom
Mach 1
http://www.mediacen.navy.mil/pubs/allhands/jan01/f14tomcat.jpg http://www.ctrl-c.liu.se/ftp/images/AVIATION/MILITARY/USA/f14/f14-3.jpg
