rESrcoDE042472
FORN,ITP 21227
MAY/JUNE 2OO1
CARIBBEANEXAMINATIONS COUNCIL ADVANCED PROFICIENCY EXAMINATION PHYSICS UNIT 01 - Paper 02 2 hours and 15 minutes
READ THE FOLLOWING INSTRUCTIONS CAREFULLY
l.
This paper consistsof NINE questions.
2.
SectionA consistsof THREE questions. Candidatesmust attemptALL questionsin this section. Answers for this sectionmust be written in this answerbooklet.
3.
Section B consistsof SIX questions. Candidatesmust attempt THREE questionsin this section,ONE question from EACH Module. Answers for this section must be written in the answer booklet provided.
4.
All working MUST be clearly shown.
Copyright@ 2001 CaribbeanExaminationsCouncil AII rightsreserved.
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-2LIST OF PHYSICAL CONSTANTS Universal gravitational constant
G
6.67x 10-lt N mt kg-t
Acceleration due to gravity
g
9.80m s-2
Radius of the Earth
RE
6380km
Mass of the Earth
ME
5.98x l02akg
Mass of the Moon
MM
7.35x 1022kg
I Atmosphere
Afin
1 . 0 0 xl O sN m - z
Boltzmann's constant
k
1.38x lo-23JK-r
Density of water
1.00x 103kg m-r
Thermal conductivity of copper
400 W m-r K-r
Specific heat capacity of aluminium
910J kg-t 6-t
Specific heat capaciryof copper
387J kg-t 6-t
Specific heat capacity of water
42W J kg-t 6-r
Specific latent heat of fusion of ice
3.34xldJkg-t
Specific latent heat of vaporisation of water
2.26x106Jkg-t
Avogadro's number
NA
6.02x 1023per mole
Molar gas constant
R
8.31J K-r mol-r
Stefan-Boltzmann constant
o
5.67x l0-8 w m-2K-4
Speedof light in vacuum
c
3.0x108ms-l
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SECTION A Attempt ALL questions. You MUST write in this answer booklet. You must NOT spend mone than 30 minutes on this section. l.
(a)
A ball is attachedto a lengthof string and is whirled in a horizontalcircle.Describe BRIEFLY how you would (i)
vary the radius of the circle it describes
[1 mark J (ii)
find the period of rotation
[2 marksJ (iii)
apply a constantforce.
[1 mark J
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(b)
Table I belorv shows a typical set of results.
Radius/m
Centripetal
Time for 50 revVs
0.2
0.47
25
0.2
0.33
30
0.2
0.22
37
0.5
0.46
40
0.5
0.33
47
0.5
0.2r
58
Thble I (i)
Use the data given in Table I to calculate the mass of the ball.
[5 marks] (ii)
what conclusioncan you draw from the datagiven in Table I ?
[1 mark J Totsl 10 marhs
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2.
In an experimentto measurethe speedof wavesin the water,a studentuseda ripple tank. The frequencyof the waveswils variedwhile the wavelengthwasmeasured.The reiults obtained are given in Table2 below.
Frequency/Hz
10 l5 20 25 30 35 N
Wavelength/cm
I
'-' -- /cm-r
wavelength
0.50 0.30 0.25 0.20 o.t7 0.15 0.13 Table 2
The student measured the wavelength using a ruler graduated in mm. (a)
Outline ONE method by which the wavelength of the waves generatedin the ripple tank could be measured accurately.
[4 marksJ
(b)
Using the values from the table, plot a graph of frequency vs l/wavelength on page 7. [4 marks]
(c)
use the graph to calculate the speedof the waves in water.
[2 marks] Total 10 marks -.-:l;.;.r,
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3.
In an experimentto measurethe Young'smodulusof a lengthof wire, seeFigure l, a student obtainedthe graph on page9 for the resultsof the load versusthe extensionof the wire. The wire had an original lengthof 3.50 m and a cross-sectional areaof 1.5 x l0-7 m2. The first measurement recordedfor the load was 30 N.
Length of wire
Sample
Scale Vernier
Load, m
Figure I (a)
(i)
List TWO necessaryprecautionsthat shouldbe takenduring this experiment.
(ii)
[2 marks] , Give ONE sourceof error that will be encounteredduring the experiment. [1 mark ]
(b)
(i)
Explain why the student'sfirst measurement was donewith a load of 30 N.
[1 mark J (ii)
Determinethe Young'smodulusfor the wire.
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[3 marks]
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Extension /mm
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-10(c)
(i)
Sketch the shapeof the graph if the elastic limit had been reachedat an extension of 6.0 mm.
[1 mark ] (ii)
What is thework donein stretchingthe wire from anextensionof 3.1 mm to an extensionof 6.2 mm?
[2 marks] Totat 10 marks
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SECTION B You must attempt THREE questionsfrom this section. ChooseONE question EACH from Module 1' 2 and 3. You MUST write your answersin the answerbooklet provided. MODULE 1 Answer EITHER Question4 OR Question5.
4.
(a)
(b)
(c)
Explain what is meantby energyand distinguishbetweenpotentialenergyand kinetic energy. [ 3 marks] (i)
What do you understandby the conservationof energy? Illustrateyour answerby making referenceto the energychangeswhen a body falls to the ground.
(ii)
Hencederivean expressionfor the velocity of the body as it hits the ground. [ 5 marks]
A car of mass1.5 x t03 kg increasesits speedfrom l0 m s-l to 30 m s-l while it is moving 400 m up a hill which is inclined at an angle o to the horizontal,where I
sin cr = 3.
A constant frictional force of 200 N resists the car's motion.
From an energy consideration, calculate the (i) (ii) (iii)
work done by the engine driving force of the engine power deivelopedby the engine at 30 m s-I .
[12 marksJ Total 20 marks
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-125.
(a)
What is meant by the following rerrns:
(i) (ii) (iii)
(b)
Speed Velocity Accelerarion
A body travels from rest for a time, /, and has an acceleration,a. obtain expressionsin terms of a and r for (i) (ii)
the final velociry, v distancetravelled, s.
Henceshowthat s= (c)
[ 3 marks]
[ 5 marks]
+(:\ z \a)
During the initial phaseof take off, a BWIA jet has an acceleration of 4.0 m s-2lasting 5 seconds' The burner engines are then turned up to full power for an accelerationof l0 m s-2. The speedneededfor takeoff is 300 m s-t. Calculatethe (i)
length of the runway
(ii)
roral time of take off.
Hence sketch a velocity-time graph for the motion of the jet.
[lZ marks]
Total 20 marks
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-13MODULE 2 AnswerEITHER Question6 or QuestionZ. 6.
(a)
Explain what is meant by the loudnessof a sound.
(b)
Describe with the aid of diagrams the responseof the ear to sound waves in terms of frequency, intensity and loudness level.
[ 2 marks]
l0m
l-1 *--_2m
-->
Loudspeaker l-l box
Figure 2 [ 6 marks] (c)
In an auditorium two loudspeaker boxes are placed as shown in Figure 2 above and made to emit identical soundsof frequency I .4YJlz.The intensity of the soundis adjusted so that it reachesa maximum of 40 dB abovethe threshold of hearing when it is measured along the line PQR.
therinePQRwhere desrmcrive interrerence causes
:t,
3:,|#*:,:[Ji;iiiffit::g
(ii)
sound atrhepoint Q. ffjiJjff:?::lffs,tyjnmj,orthe [12 marks] Total 20 marks
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(a)
Explain what is meant by mechanical resonance.
o)
Describe Two practical cases in which the resonance that occurs is desirable and Two casesin which it is not. Explain how damping may be achievedin the undesirable cases. [ 6 marks]
(c)
The human leg may be consideredto be a compound pendulum which pivoted about the hip joint and walking is most effortless when itr" t.gr swing at their natural frequency.
[ 2 marks]
For a leg of length, /, and mass m, its natural period of oscillation is given by
fI
r = znf,
whereI = its rotationalinertiaandr is the distanceof the centre +is *, of massof the leg from the pivot point. (i)
Determine, T, for a leg which is 0.9 m long, if the centre of mass is mid-way along the leg.
(ii)
Determine the speed of walking (in km h-l) which is most effortless, if the person takes stepsthat are 0.g m long.
(iii)
calculate the maximum accelerationof the leg during the walk. [12 marksJ Iotal 20 marks
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MODULE 3 Answer EITHER Question8 or euestion 9. 8.
(a)
(i) (ii)
(b)
List TWO factorswhich would affectthe rateof evaporation of a liquid. Explainin termsof the kinetic theorywhy eachof thesefactorsaffectsthe rate of evaporation. [4 marks]
According to the kinetic theory of gases,the pressure,P, of an ideal gas is related to the mean-square-speed<c2> of its molecules by the expression
P - lU 3
V
<cz>
where V is the volume occupied by the gas, N is the number of molecules and m is the mass of a molecule of the gas. (i)
StateTHREE assumptionsof the kinetic theory of gaseswhich are used in the derivation of the expression above.
(ii)
Write down the equation of statefor an ideal gas in terms of its thermodynamic temperatureT, stating what each symbol represents.
(iii)
Hence, show that the average kinetic energy, E*, of a molecule of an ideal gas can be written as ?
Ek = jnRT wherethe symbolshavetheir usualmeaning. (c)
[9 marksJ
A containerholds 40 x l0-3 m3 of helium gas at a pressureof 2.4 x lOs Pa when the temperatureis 320 K. Calculatethe (i) tiil (iii)
number of moles of helium in the container number of helium atoms in the container averagekinetic energy, &, of an atom of helium in the container. [5 marks]
(d)
The gas is now heatedto 600 K while the volume is allowed to remain constant. Calculate the final pressure of the gas. [2 marhs]
Total 20 marks
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- 16 9.
(a)
Define (i) (ii) (iii)
(b)
heatcapacity specificheatcapaciry specificlarentheatof fusion.
[3 marks]
With what physical change is EACH quantity defined in part (a) associated. [2 marks]
(c)
A student has been asked to determine the specific heat capacity of the block shown in Figure 3 by an electrical method. She has available a variable 15 V supply, an immersion heater, a voluneter, an ammeter, a top-pan balance, a thermometer and a stopwatch. The heater is used to heat the block for a fixed time. The student's results are shown in the table below Mass of bloclc/kg P.d across heaterA/ Current supplied to heater/A Initial temperature of blocUoC Final temperature of blocUoC Heating time/s
0.995 13.2 3.3s 31.0 65.0 300
Hole for thermometer
Insulated mat
Figure 3 (i)
Draw a diagram of an electrical circuit that is connectedto the heaterduring the experiment.
(ii)
Using the data in the table above, calculate the specific heat capacity of the block. [6 marks]
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_t t _ (d)
Another student was asked to examine how the temperature varies with time when a block of ice of mass4.0 kg is_heatedwith an immersion heaterof.power 4O0W placed in oC it. The ice is initially at -10 and it is assumedthat all the heat is transferred from the heaterto the ice.
Calculatethe time takento (i) (ii)
(e)
hearrheice from -10 oC to 100oC vaporizeall the water at 100oC.
[6 marks]
Draw a graph, with labelled axes, to show how the temperature varies with time throughout the entire heating process. [3 martrsJ
(Specificheatcapacityof ice, C, = 2100J kg-t k-t.) Total 20 marks
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