This document discusses the Doppler effect and sonic booms. It provides background on the Doppler effect, explaining that Austrian physicist Christian Doppler first proposed in 1842 that the observed frequency of waves depends on the relative speed of the source and observer. When a source of waves is moving toward the observer, the observed frequency is higher than the emitted frequency, and when receding the observed frequency is lower. The document then discusses how sources moving faster than the speed of sound in air can create sonic booms, with pressure waves forming ahead and behind the source.

1. DOPPLER EFFECT
AND
SONIC BOOM
TEACHER: MS. KATHLEEN BOOTH
SUBJECT: PHYSICS
PRESENTED BY: SANGANAK KASARE

2. SHELDON COOPER AND DOPPLER EFFECT

3. HISTORY OF DOPPLER EFFECT
• In 1984 an Australian Physicist and mathematician, JC Doppler
studied the behaviour of waves as the source, receiver or both are
moving.
• He proposed as the source is moving the waves at the front have a
higher frequency compared to the source being stationary.
• Also the waves trilling behind the source have a lower frequency
compared to the source being stationary.
• The variation in frequencies is noticed by human ears as the change
in pitch as the source moves.

4. DOPPELR EFFECT
• All waves travel outwards from the source (propagate).
• Stationary sources have waves moving outwards in a circular
pattern.
• Moving source: waves ahead of the source are bunched closer.
waves trailing behind the source are spread out.
• This is heard as a: high pitched sound at the front of the source and a
distant drop in pitch as the moving source passes by.

5. MOVING SOURCE
APPROACHING A
STATIONARY
RECEIVER
The Doppler Effect for a person
throwing a ball at constant velocity
every second and traveling at 1 m.s-1
towards the wall.

6. CALCULATING THE OBSERVED FREQUENCY
• f- frequency observed
• f0- frequency emitted by the source
• c- is the velocity of waves in the
medium
• Vr- is the velocity of the receiver
relative to the medium.
• Vs- is the velocity of the source
relative to the medium

7. SOURCE MOVING AT THE SPEED OF SOUND
• The receiver in the front of the
source will not receive any
sound as all the sound waves
are bunched at the source.
f =
c + 0
c - c
*f0( )
=
c * f0
0
= undefined

8. SOURCE MOVING FASTER THEN THE SPEED OF SOUND
• The receiver in the front of the
source will not receive any
sound waves As the waves are
slower then the source and are
trailing behind the source.
f =
c + 0
c - 2c
*f0( )
=
c * f0
-c
= Negative frequency

9. SOURCE MOVING FASTER THEN THE SPEED OF SOUND
• The receiver behind the source will
hear the sound waves emitted from
the source.
• This source radiates 2 waves: a
pressure wave (Mach wave) and
sound wave.
• These waves combine to create the
shockwaves (sonic boom).
• The intensity of the boom increases
as the speed of the source
increases.

10. Mark waves
Aircraft moving faster then the speed
of sound and creating 2 pressure
waves; at the head (point of pressure
rise) and the tail (point of sudden drop
in pressure).

11. BIBLIOGRAPHY
• "What HappensWhen an Aircraft Breaks the Sound Barrier?" Scientific Americans.
Scientific American, a Division of Nature America, Inc., 11 Mar. 2002.Web. 5 Oct. 2015.
<http://www.scientificamerican.com/article/what-happens-when-an-airc/>.
• Kaouri, Katerina. "The Sonic Boom Problem." YouTube.YouTube, 10 Feb. 2015. Web. 05
Oct. 2015. <https://www.youtube.com/watch?v=JO4_VHM69oI>.
• "6.3The Doppler Effect." Physics Uconn.Web. 5 Oct. 2015.
<http://www.phys.uconn.edu/~gibson/Notes/Section6_3/Sec6_3.htm>.
• "Doppler Effect." The for Sound. Hyperphysic. Web. 05 Oct. 2015.
<http://hyperphysics.phy-astr.gsu.edu/hbase/sound/dopp.html>.
• "Breaking the Sound Barrier with an Aircraft." The Sound. Hyperphysics. Web.
<http://hyperphysics.phy-astr.gsu.edu/hbase/sound/soubar.html>.
• UNSW. "The Doppler Effect - A Multimedia Presentation from Physclips." The Doppler
Effect - A Multimedia Presentation from Physclips. School of Physics – UNSW. Web. 05
Oct. 2015. <http://www.animations.physics.unsw.edu.au/waves-sound/Doppler/>.