Physical Science P1 Additional Exemplar Memo ... - SmartLearner

Physical Sciences/Fisiese Wetenskappe/P1/V1 9
DoE/Exemplar/Model 2008
NSC/NSS – Memorandum
QUESTION 8/VRAAG 8
8.1 Doppler effect/Doppler-effek
8.2
A change in observed frequency (pitch) due to relative motion between
observer and sound source./'n Verandering in waargenome frekwensie
(toonhoogte) wanneer daar relatiewe beweging tussen 'n klankbron en
'n waarnemer is.
OR/OF
A change in observed frequency (pitch) because the sound source and
observer have different velocities with respect to the medium./ 'n
Verandering in waargenome frekwensie (toonhoogte) omdat die bron
en die waarnemer verskillende snelhede ten opsigte van die medium
het. [12.2.1] (3)
f
v ± v
L
L = s
v ± v s
f
When car approaches/Wanneer motor nader beweeg:
340 + v L
f (approach/ nader ) = ( )700
L
340 ± 0
When car moves away/Wanneer motor weg beweeg:
340 − v L
f (away/ weg) = ( )700
L
340 ± 0
340 + v 340 − v
L
L
( ) 700 - ( )700 = 80
340 ± 0 340 ± 0
700
∴ (340 + vL – 340 + vL) = 80
340
∴ vL = 19,43 m·s -1
OR/OF
f
v ± v
L
L = fs
v ± v s
f
f
L
L
(approach/
(away/
v + v
L
nader ) = ( )f s
v − v
v ± 0
L
weg ) = ( )f s
v ± 0
f (approach/ nader ) - (away/ )
L
v + v
v − v
= 80
v ± 0
2( 700)
v L
=
340
L L f weg = ( )f - ( )f
L s
s
v ± 0
f v s
∴ 80 =
v
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2 L
∴vL = 19,43 m·s -1
[12.1.3]
(5)
[8]