UgandaAdv

ancedCert
if
icat
eofEducat
ion
PRE-
MOCKEXAMI NATIONS-2012
PHYSI
CS
Paper1
2hours30minutes

I
NSTRUCTIONSTOCANDI DATES:
 Attemptanyfivequest
ions,
incl
udingatleastonefrom eachoft
hesect
ionsA,
B
andC butNOTmor ethantwoquestionsfrom eachSection.
 Sil
entnon-
programmablescient
if
icelect
roniccal
culat
orsmaybeused
 Wherenecessaryassume;
El
ect
roni
cchar
ge,
(e) 6x10-19C
=1.
Accel
erat
ionduet
ogr
avi
ty,
(g) =9. s2
81m/
El
ect
roni
cmass,
(me) 11x10-31kg
=9.
Massoft
heear
th,
(ME) 97x1024kg
=5.
Pl
ank’
sconst
ant
,(h) 6x10-34Js
=6.
St
efan’
sconst
ant
,() 7x10-8Wm-2K1
=5.
Radi
usofear
th(
Re) 4x106m
=6.
Radi
usoft
hesun,
(Rs) 0x108m
=7.
Speedofl
i
ghti
nav
acuum (
C) 0x108m/
=3. s
Speci
fi
cheatcapaci
tyofwat
er(
c) =4200Jkg-1k-1
Uni
ver
salGr
avi
tat
ionconst
ant
,(G) 67x10-11Nm2kg-2
=6.
Av
ogadr
o’snumber
,(NA) 02x1023mol
=6. -
8

Densi
tyofwat
er =103kgm-1
Char
get
omassr
ati
on,
(e/
m) 8x1011Ckg-1
=1.
1U =931MeV
Radi
usofear
th’
sor
bitaboutt
hesun 5x1011m
=1.
-
1 -
Gasconst
ant
,R =8.
31JmolK1

1
 SECTI
ONA

1.a)i
)InWhatci r
cumstancescananobj ectmovewit
hconstantspeedandyet be
accel
erat
ing? (1mark)
ii
)Definetheterm angul
arveloci
tyw. (
1mar
k)
i
ii
)Anobj ectdescri
bedacircul
arpathofradi
us,r
.Deri
veanexpr essi
oni
n ter
ms
ofrandwf orthespeedwithwhichitdescri
bedt
hecircl
e.(
3mar ks)

b)Adartplayerst ands3.0m f
rom thewallonwhichaboardhangsandt
hrows adart
whichl
eav eshishandwi t
hahor i
zontalvel
oci
tyatapoi
nt1.80m abov ethegr
ound.
Thedartstri
kest heboardatapoi nt1.5m f
rom t
he gr ound.Cal
cul
atet
he;
i
)t i
meoff li
ght, (
3marks)
i
i)init
ialspeedoft hedart
, (
2marks)
i
ii)speedoft hedartwhenithit
stheboard. (
2marks)

c)Expl
ainwhyar aci
ngcartr
avel
sfast
eronabankedt
rackt
hanonal
evelt
rackoft
he
sameradiusofcurvat
ure. (2mar
ks)

d)Apendl um bobofmass0.2kgisattachedt
ooneendofaninel
ast
icst
ri
ngof l engt
h
0
1.2m.Thebobmov esinahori
zontal
circl
ewit
hthest
ri
ngincl
i
nedat 30 tothe
vert
ical
.Calculat
ethe;
i
)tensioninthest
ri
ng, (3marsk)
i
i)peri
odofmot i
on. (
3marks)

2.a)i)Whati smeantbyt het ermsst r

ess, strainandy oung’smodul us?(3mar ks)
i
i)Der i
veanexpr essionf ortheener gystor edi naunitvolumeofast retched el asti
c
mat eri
al, expressingy ourresultsi
nt ermsoft hey oung’smodul us andt hest r
ai nofthe
mat eri
al. (4marks)
ii
i)Acopperwi reandast eelwir
eeachofl engt h1m andar eaofcross- sect ion
2
1.0mm ar elaidsidebysi deandj oinedt ogetheratt heends.The composi tewi r
eis
thenplacedv er
tical
lywi t
ht heupperendcl ampedand thelowerendsuppor ti
nga
massof800g.Cal culatethet ensi
oni nthewi res andtheel ast
icpotenti
al energy
ofthesy stem. (5mar ks)
[
young’ smodul usofcopperandst eel i
s1. 2x1011Nm-2and2. 0x1011Nm-2
respectively]

b)i)Def i
nethet m sur
er f
acetensionint
ermsofsurf
aceenergy. (
1mark)
i
i)Calculat
etheworkdoneagainstsur
facet
ensi
onfor
cesinblowi
ngasoap bubbl
e
ofdiameter15mm ifthesur
facetensi
onofthesoapsol
uti
onis
0x10-2Nm-1.
3. (
3mar
ks)

c)i)Whati smeantbytheterm momentofaf orce? (

1mark)
i
i)Awheel ofradius0.
60m ispivotedatit
scentre.Atangenti
alfor
ceof4.
0N acts
ont hewheelsothatthewheel r
otateswithauniformveloci
ty.Fi
ndthe wor kdoneby
thef or
cetotur
nt hewheelthr
ough10r ev
oluti
ons. ( 3mar ks)
3.a)St eNewt
at on’slawsofmot ion. (
3mar
ks)

b)i)Defnel
i i
nearmomentum andstatethelawofconservati
onofli
near
moment um. (2marks)
i
i
)Amot orcart
rav
eli
ngataveloci
tyof72kmh-1sl
owsdownt oone-
fi
ft
hofits
or
igi
nalvel
oci
tyontheappl
i
cati
onofbr akes,
inati
mei nt
erv
al of15 seconds.
2
Giv
ent hatt
hemassofthemot orcaris750kg,
calculat
ethe av
erager
etardingforceon
i
tdur i
ngthi
stime. (4marks)
i
ii
)Apar t
icl
e,P,ofmassm1mov i
ngwithaveloci
tyU1col
li
deswithastaionary
part
icl
eQofmassm2.I fthecol
li
sionisel
asti
candt hevel
oci
tyofpandQ af teri
mpact
ar
ev1andv
2respect
ivel
y,showt
hati
f ,
then

. (
4mar
ks)

c)Whati
smeantbyt
het
erm si
mpl
ehar
moni
cmot
ion? (
1mar
k)

d)Thediagr
am bel
owshowsamassof0. 3kgconnectedbyt
woident
icalstr
etched
spri
ngsoffor
ceconst
ant2.5Nm-1.Themassisdispl
acedby20mm to thelef
tofit
s
equi
li
bri
um posi
ti
onandthenrel
eased.

0.
3kg

Smoot
hgr
ound
Fi
g.1

I
fthemassosci l
l
ateswithsimpl
eharmoni
cmoti
on,
cal
cul
atet
he;
i
)peri
odicti
me, (3mar
ks)
i
i
)accelerat
ionatthecentr
eandext
remeends. (
3mar
ks)

chKepl
4.a)Sket er’
slawsofpl
anet
arymot
ion. (
3mar
ks)

b)i
)Assumi ngthatpl
anetsar emovi
ngi nci
rcul
arorbi
tapplyKepler
’sl
awst o
showt hattheaccelerat
ionofaplaneti
sinver
selyproport
ional
tothe
squar eofitsdist
ancef r
om thesun. (3marks)
i
i)Explainthesigni
ficanceofthi
sandshowhowi tleadstoNewton’
s
universallawofgrav i
tat
ion. (2marks)

c)i)Obt aintheval
ueofgfrom t
hemot i
onofthemoon, assumingthatit
speriod of
rot
ationar oundtheeart
his27days8hoursandtheradi
usofi t
sorbitis 60. 1ti
mes
theradiusoft heeart
h. (
4mar sk)
i
i)Ex plainbri
efl
yhowworldwideradi
oortel
evisi
oncommuni cati
onscanbe
achievedwi t
hthehel
pofsatel
li
tes. (2marks)

d)Dist
ingui weenf
shbet undament
alandder
ivedphy
sicalquant
it
ies.Gi
veone
exampleofeach. (2marks)

e)At
ruckofmass1000kgi
spul
l
ingat
rai
l
erofmass3000kgonahor
izont
al
gr
oundonwhi
cht
hecoef
fi
cientoff
ri
cti
onbet
weent
het
ruckandt
he gr
oundi
s

3
whi
l
ethatbet
weent
het
rai
l
erandt
hegr
oundi
s .
Gi
venthattheengi
neofthetr
uckexer
tsaforceof8000N,calcul
atethe
accel
erat
ionofthetr
uckandtrai
l
er,
andthetensi
oninthetwo-bar connecti
ngt
he
tr
uckandt r
ail
er. (4marks)

SECTI
ONB

5.a)i
)St
atef
ourassumpt
ionsmadei
nder
ivat
ionoft
heexpr
essi
on f
or
anidealgas. (
2marks)
i
i
)Whi choft heassumpt i
onsin(i
)aboveneedtobemodi f
iedt
oaccount
forr
eal gases?Di scusshowthesemodifi
cati
onaffecttheequat
ionof
stat
eofani deal gas. (
4marks)
i
i
i)Calculatetherootmeansquar espeedofthemoleculesofanidealgas
at1270Cgi venthatthedensit
yofthegasatapressureof1.0x105Nm-2
andat emper at
ureof00Ci 43kgm-3.
s1. (4marks)

b)i)Whatismeantbycr it
icaltemperat
ureofagas? (
1mark)
i
i)Drawal abel
edP-Vdiagr am t
oshowt hebehaviourofarealgasunder
compressionfortemperaturesaboveandcrit
icalt
emper at
ure. (
3marks)
ii
i)Explai
nwhyar ealgasbehav esl
ikeanidealgasattemperatureabove
cri
ti
caltemperatur
e. (
1mark)

c)i)StateDalton’sl
awofpar ti
alpressures. (
1mar
k)
i
i)Airsaturatedwit
hwat ervapourisconsignedi
nacont ainerata
temper at
ureof270Candapr essureof1.0x105Pa.Atat emperatureof770C
5
thepressur eis1.
6x10Paandt heairremainssat
urated.Fi
ndt hesatur
ati
on
vapourpr essureofwaterat770C.Takesat ur
atedvapourpressureofwater
at270Cas3. 6x103Nm-2. (4marks)

4
6.a)i)Statethedesi
rableproper
ti
esamater
ialmusthavet
obeusedasa
ther
momet ri
csubstance. (
2mar
ks)
i
i)Explai
nwhyaconst ant–vol
umegasthermometeri
susedt
ocali
brate
otherther
momet ers. (2mar
ks)

b)Descr
ibewi
tht
heai
dofal
abel
eddi am howanopt
agr icalpy
rometercan
beusedt
omeasurehi
ght
emper
atur
es. (
6marks)

c)Whatismeantbyt hef
oll
owi
ngt
erms?
i)heatcapacit
y, (
1mar
k)
i)l
i atentheat
. (
1mar
k)

d)Twot apsar erunningint

oabat h.Thehotwat sat0andi
eri tisrunni
nginatar ateof
6.0x10-2m3mi n-1whil
ethecoldwat erisat100Candrunni
ngatarate of9x10-
2 3
m min-1.Givent hatt
hecapacityofthewat erbathi
s3.0m3andi
ts normal oper
ating
0
temperat ureis40C.Cal culat
e;
i
)thet i
met akentof i
l
l t
hewaterbat h. (2marks)
i
i)t
het emper atur
eoft hehotwat er (
3marks)
i
ii
)st ateanyassumpt i
onsmade. (1mark)

e)Expl
ainwhyt
het
emper
atur
eremai
nsconst
antdur
ingchangeofst
ate.
(
2mar
ks)

7.a)Statethecondit
ionsnecessaryandexpl
aint
heener
gychangewhi
cht
ake
placein
)ar
i eversi
blei
sothermalchange (3mar
ks)
i
i)areversi
bleadiabati
cchange (3mar
ks)

b)Explainwhyanadi
abat
ici
ssteepert
hananisothemal att
hesame
condit
ionsofstat
e. (3marks)
c)i)Showt hatt
hewor
kdoneduri
ngar ev
ersi
bleadiabat
icprocessisgi
venby

Wher
ei
sther
ati
ooft
hepr
inci
pal
heatcapaci
ti
es. (
5mar
ks)

d)Ani deal gasinacy l

inderiscompressedadiabat
icall
ysothatit
sf i
nal
volume isone-
fi
fthofi t
si nit
ialvolume.Thegashas=1. 4anditsinit
ial
temperature andpr essur
e
0 3
are17Cand1. 0x10Pa, respecti
vel
y.
i)Whati sthefinalpressureandtemperat
ureoft hegas? (
4marks)
ii
)Cal culatethewor kdonebyt hegasduringthecompr essi
on. (2marks)

5
 SECTI
ONC

8.a)Def
inebi
ndi
ngener
gyofanucl
i
de. (
1mar
k)

b)i
)Sketchagraphshowi
nghowbi ndi
ngener
gypernucl
eonv
ari
eswi
th
massnumber. (2mar
ks)
i
i
)Explai
nthemainfeat
uresoft
hegraphin(
b)(i
)above. (2mar
ks)

c)Descr
ibet
hest
ruct
ureandact
ionofacl
oudchamber
. (
5mar
ks)

d)Aradioact
ivesour
cecontai
ns1.0x10-9kgofpl
utoni
um (massnumber239)
.
Thesourceisest
imatedtoemitatot
alof2300alphapart
icl
espersecondi
n al
l
di
rect
ions.Cal
culat
ethehal
fli
feofpl
utoni
um. (4mar
ks)

e)Consi
dert
henucl
earr
eact
ionbel
ow.

i
)Fi
ndt
hev
aluesof and . (
2mar
ks)
i
i
)Calculat
etheener
gyr
eleasedbyonemol
eof i
ntheabov
e
r
eact
ion. (
4mar
ks)

Assume =235.
1175

=1.
0090

=143.
9577

=88.
9264

9.a)i
)Whatismeantbytheterm speci
fi
cchargeofanelect
ron? (1mark)
i
i)Descr
ibeanexper
imenttodeter
minetheval
ueforthespeci
fi
ccharge
ofanelect
ron. (6mar
ks)

b)Achar gedoildropf al
lsataconst antspeedi nthemil
li
kanoil
experi
ment when
thereisnop. dbet weent heplat
es.
i)Explainthemot i
onoftheoi ldrop. (
2mar ks)
ii
)Anoi l
dropofmass4. 0x10-18kgi sheldstati
onarybet
weenthehorizont al
-
19
plateswhent hedropcarries6el ectri
cchargeseachofval
ue1.6x10 C,
calcul
atet hev al
ueoft heelectr
icfieldstrength. (4marks)

6
c)Ionshavingchar ge,Qandmass,m ar
eacceler
atedfrom restt
hrougha
potenti
aldi
fference,V.Theyt
henmov ei
ntoaregi
onofuni f
orm magnet i
cfiel
doff
lux
density
,Bact i
ngatr i
ghtangl
estot
hedir
ecti
onoftravelofthe ions.
i)Showthatt hespeed,wit
hwhicht
heionsenterthemagnet i
cfiel
disgiv
en

by
; . (
4mar
ks)

i
i
)Obtai
nanexpr
essi
onf
ort
her
adi
us,
roft
hepat
hoft
hei
onsi
nthe
magnet
icf
iel
d. (
3mar
ks)

10.a)i)Whatarex-
rays? (1mar
k)
i
i)Wi
ththeaidofalabeleddi
agr
am,descri
behowanx-r
aytubeworks.
(5mar
ks)
i
ii
)Descri
betheenergychangest
hatoccuri
nanx-r
ayt
ubeinoperat
ion.
(2mar
ks)

b)Inanx- r
ayt ubeoperat
edat1.3x103V, t
hetar geti
smadeofamat eri
alof
2 -
1 -1
specifi
cheatcapaci t
y2.3x10Jkg k andhasamassof0. 23kg.One per centof
theelectr
icpowersuppl i
edi
sconv ertedi ntox-raysandtherest i sdissipat
edas
-
1
heatinthet ar
get.Ift
hetemperatur
eoft het ar
getr i
sesby 8kg , f
ind;
i
)numberofel ectr
onswhi
chst ri
kest het argeteverysecond. ( 5mar sk)
i
i)shortestwav el
engt
hofx-rayspr oduced. (2mar ks)

c)Explai
nthephysicalprocesst
hataccountf
or
i
)cutoffwavelength (
2mar
ks)
i
i)char
acter
ist
iclines,i
nanx-r
aytube. (
3mar
sk)

*
**END*
**