1
HESIbA2bVERSIONb1
READINGbCOMPEHENSION
DopplerbEffect
Havebyoubeverbwonderedbwhybthebwhistlebofbabtraveling,bdistantblocomotivebpredictsbitsbapproachbs
everalbyardsbbeforebanyonebactuallybseesbit?bOrbwhybanboncomingbambulance’sbscreamingbsirenbisb
heardbmomentarilybseveralbfeetbbeforebthebambulancebcomesbintobfullbview,bbeforebitbpassesbyou,ba
ndbwhybitsbsirenbisbstillbheardbfaintlybwellbafterbthebambulancebisboutbofbsight?
WhatbyoubarebwitnessingbisbabscientificbphenomenonbknownbasbthebDopplerbEffect.bWhatbtakesbpla
cebisbtrulybremarkable.bInbbothbofbthesebinstances,bwhenbthebtrainborbambulancebmovesbtowardbthebs
oundbwavesbinbfrontbofbit,bthebsoundbwavesbarebpulledbcloserbtogetherbandbhavebabhigherbfrequency.
bInbeitherbinstance,btheblistenerbpositionedbinbfront bofbthebmovingbobject bhearsbabhigherbpitch.bTheba
mbulancebandblocomotivebarebprogressivelybmovingbawaybfrombthebsoundbwavesbbehindbthem,bca
usingbthebwavesbtobbebfartherbapartbandbtobhavebablowerbfrequency.bThesebfast-
bapproachingbmodesbofbtransportationbdistancebthemselvesbpast btheblistener,bwhobhearsbablowerbpit
ch.
1. Whichbstatementbisbnotblistedbasbabdetailbinbthebpassage?
A. Theboncomingbsoundbwavesbhavebabhigherbpitchbbecausebofbhighbfrequencybandbclosenessbo
fbwaves.
B. Theboncomingbsoundbwavesbhavebabhigherbpitchbbecausebofblowbfrequencybandbclosenessbo
fbwaves.
C. Thebwhistlingbsoundbofbtheblocomotivebasbitbapproachesbandbpassesbcanbbebexplainedbbybt
hebDopplerbeffect.
D. Thebhigh-
pitchedbsoundbofbthebambulancebasbitbapproachesbandbpassesbcanbbebexplainedbbybthebDopplerbeff
ect.
2. Whatbisbthebmainbideabofbthebpassage?
A. Trainsbandbambulancesbmakebdistinctlybloudbnoises.
B. Low-frequencybwavesbmakebhigh-pitchedbsounds.
C. High-frequencybwavesbmakeblow-pitchedbsounds.
D. ThebDopplerbEffectbexplainsbthebrationalebforbwhybsoundbisbheardbinitiallybmorebstronglyba
ndbthenbfaintlybafterbabmovingbobjectbhasbpassed.
, 2
3. Whatbisbthebmeaningbofbthebwordbphenomenonbinbthebsecondbparagraph?
A. Somethingbthatbisblifelessbtobthebsenses
, 3
B. Somethingbthatbisbnonchalant
C. Somethingbthatbisbsignificantbbutbunusual
D. Somethingbthatbisbchemicalbinborigin
4. Whatbisbthebauthor’sbprimarybpurposebinbwritingbthisbessay?
A. Tobentertainbthebreaderbwithbinformationbaboutbtrainsbandbambulances
B. Tobinformbthebreaderbaboutbavoidingbaccidents,bwhichbinvolvebtrainsbandbambulances
C. Tobinformbthebreaderbaboutbhowbmovementbaffectsbsound
D. Tobanalyzebthebdifferencebbetweenbtrainbandbambulancebsounds
5. Whichbsoundbwavesbhavebabhigherbpitch?
A. Thosebwavesbthatbarebcloserbtogether
B. Thosebwavesbthatbarebfartherbapart
C. Thosebwavesbthatbtravelbablongbdistance
D. Thosebwavesbthatbtravelbabshortbdistance
6. Whichbsoundbwavesbhavebablowerbpitch?
A. Thosebwavesbthatbarebcloserbtogether
B. Thosebwavesbthatbarebfartherbapart
C. Thosebwavesbthatbtravelbablongbdistance
D. Thosebwavesbthatbtravelbabshortbdistance
Electrocardiogram
Beep!…Beep!…Beep!bisbthebaudiblebrhythmicbsoundbmadebasbthebstrengthbofbthebheartbmusclebisb
measured.
Thebsignalbcadencebhasbabcharacteristicbrecordbthatbvariesbinbeverybindividual.bThisbre
cordbisbcalledbanbelectrocardiogram,borbECG.
Inbthebbody,banbarraybofbsystemicbneuralbresponsesbconstantlyboccur,bemittingbelectricbcurrents.bT
hebelectricbcurrentsbcanbbebdetectedbonbthebsurfacebofbthebbody,bandbifbabpersonbisbhookedbtobanbam
plifier,bthesebimpulsesbarebrecordedbbybanbelectrocardiograph.
Mostbofbthebinformationbobtainedbisbaboutbthebheartbbecausebthebheartbsendsboutbelectricbcurrents
, 4
in
waves.bThisb―wavebofbexcitation‖bspreadsbthroughbthebheartbwallbandbisbaccompaniedbbybe
lectricbchanges.bThebwavebtakesbplacebinbthreebdistinctbsteps.
Initially,btheb―wavebofbexcitation‖baccompaniedbbybanbelectricbchangeblastsbforbapproximatelyb1btob
2bsecondsbafterbthebcontractionbofbthebcardiacbmuscle.bThebelectricbimpulsesbarebdischarged
HESIbA2bVERSIONb1
READINGbCOMPEHENSION
DopplerbEffect
Havebyoubeverbwonderedbwhybthebwhistlebofbabtraveling,bdistantblocomotivebpredictsbitsbapproachbs
everalbyardsbbeforebanyonebactuallybseesbit?bOrbwhybanboncomingbambulance’sbscreamingbsirenbisb
heardbmomentarilybseveralbfeetbbeforebthebambulancebcomesbintobfullbview,bbeforebitbpassesbyou,ba
ndbwhybitsbsirenbisbstillbheardbfaintlybwellbafterbthebambulancebisboutbofbsight?
WhatbyoubarebwitnessingbisbabscientificbphenomenonbknownbasbthebDopplerbEffect.bWhatbtakesbpla
cebisbtrulybremarkable.bInbbothbofbthesebinstances,bwhenbthebtrainborbambulancebmovesbtowardbthebs
oundbwavesbinbfrontbofbit,bthebsoundbwavesbarebpulledbcloserbtogetherbandbhavebabhigherbfrequency.
bInbeitherbinstance,btheblistenerbpositionedbinbfront bofbthebmovingbobject bhearsbabhigherbpitch.bTheba
mbulancebandblocomotivebarebprogressivelybmovingbawaybfrombthebsoundbwavesbbehindbthem,bca
usingbthebwavesbtobbebfartherbapartbandbtobhavebablowerbfrequency.bThesebfast-
bapproachingbmodesbofbtransportationbdistancebthemselvesbpast btheblistener,bwhobhearsbablowerbpit
ch.
1. Whichbstatementbisbnotblistedbasbabdetailbinbthebpassage?
A. Theboncomingbsoundbwavesbhavebabhigherbpitchbbecausebofbhighbfrequencybandbclosenessbo
fbwaves.
B. Theboncomingbsoundbwavesbhavebabhigherbpitchbbecausebofblowbfrequencybandbclosenessbo
fbwaves.
C. Thebwhistlingbsoundbofbtheblocomotivebasbitbapproachesbandbpassesbcanbbebexplainedbbybt
hebDopplerbeffect.
D. Thebhigh-
pitchedbsoundbofbthebambulancebasbitbapproachesbandbpassesbcanbbebexplainedbbybthebDopplerbeff
ect.
2. Whatbisbthebmainbideabofbthebpassage?
A. Trainsbandbambulancesbmakebdistinctlybloudbnoises.
B. Low-frequencybwavesbmakebhigh-pitchedbsounds.
C. High-frequencybwavesbmakeblow-pitchedbsounds.
D. ThebDopplerbEffectbexplainsbthebrationalebforbwhybsoundbisbheardbinitiallybmorebstronglyba
ndbthenbfaintlybafterbabmovingbobjectbhasbpassed.
, 2
3. Whatbisbthebmeaningbofbthebwordbphenomenonbinbthebsecondbparagraph?
A. Somethingbthatbisblifelessbtobthebsenses
, 3
B. Somethingbthatbisbnonchalant
C. Somethingbthatbisbsignificantbbutbunusual
D. Somethingbthatbisbchemicalbinborigin
4. Whatbisbthebauthor’sbprimarybpurposebinbwritingbthisbessay?
A. Tobentertainbthebreaderbwithbinformationbaboutbtrainsbandbambulances
B. Tobinformbthebreaderbaboutbavoidingbaccidents,bwhichbinvolvebtrainsbandbambulances
C. Tobinformbthebreaderbaboutbhowbmovementbaffectsbsound
D. Tobanalyzebthebdifferencebbetweenbtrainbandbambulancebsounds
5. Whichbsoundbwavesbhavebabhigherbpitch?
A. Thosebwavesbthatbarebcloserbtogether
B. Thosebwavesbthatbarebfartherbapart
C. Thosebwavesbthatbtravelbablongbdistance
D. Thosebwavesbthatbtravelbabshortbdistance
6. Whichbsoundbwavesbhavebablowerbpitch?
A. Thosebwavesbthatbarebcloserbtogether
B. Thosebwavesbthatbarebfartherbapart
C. Thosebwavesbthatbtravelbablongbdistance
D. Thosebwavesbthatbtravelbabshortbdistance
Electrocardiogram
Beep!…Beep!…Beep!bisbthebaudiblebrhythmicbsoundbmadebasbthebstrengthbofbthebheartbmusclebisb
measured.
Thebsignalbcadencebhasbabcharacteristicbrecordbthatbvariesbinbeverybindividual.bThisbre
cordbisbcalledbanbelectrocardiogram,borbECG.
Inbthebbody,banbarraybofbsystemicbneuralbresponsesbconstantlyboccur,bemittingbelectricbcurrents.bT
hebelectricbcurrentsbcanbbebdetectedbonbthebsurfacebofbthebbody,bandbifbabpersonbisbhookedbtobanbam
plifier,bthesebimpulsesbarebrecordedbbybanbelectrocardiograph.
Mostbofbthebinformationbobtainedbisbaboutbthebheartbbecausebthebheartbsendsboutbelectricbcurrents
, 4
in
waves.bThisb―wavebofbexcitation‖bspreadsbthroughbthebheartbwallbandbisbaccompaniedbbybe
lectricbchanges.bThebwavebtakesbplacebinbthreebdistinctbsteps.
Initially,btheb―wavebofbexcitation‖baccompaniedbbybanbelectricbchangeblastsbforbapproximatelyb1btob
2bsecondsbafterbthebcontractionbofbthebcardiacbmuscle.bThebelectricbimpulsesbarebdischarged
