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9702_w11_ms_22.pdf

9702_w11_ms_22.pdf
9702_w11_ms_22.pdf

UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONS

GCE Advanced Subsidiary Level and GCE Advanced Level

MARK SCHEME for the October/November 2011 question paper

for the guidance of teachers

9702 PHYSICS

9702/22

Paper 2 (AS Structured Questions), maximum raw mark 60

This mark scheme is published as an aid to teachers and candidates, to indicate the requirements of the examination. It shows the basis on which Examiners were instructed to award marks. It does not indicate the details of the discussions that took place at an Examiners’ meeting before marking began, which would have considered the acceptability of alternative answers.

Mark schemes must be read in conjunction with the question papers and the report on the examination.

? Cambridge will not enter into discussions or correspondence in connection with these mark schemes.

Cambridge is publishing the mark schemes for the October/November 2011 question papers for most IGCSE, GCE Advanced Level and Advanced Subsidiary Level syllabuses and some Ordinary Level syllabuses.

w w w .X t r e m e P

a p e r s .

c o m

1 (a) average velocity = 540 / 30C1

18m s–1 A1

=

[2]

(b)

velocity zero at time t = 0B1

positive value and horizontal line for time t = 5s to 35s B1

line / curve through v = 0 at t = 45s to negative velocity B1

negative horizontal line from 53s with magnitude less than positive value and

horizontal line to time = 100s B1

[4] 2 (a) (i) force is rate of change of momentum B1 [1]

(ii) work done is the product of the force and the distance moved in the direction

of the force B1 [1]

(i) W = Fs or W = mas or W = m(v2 – u2) / 2 or W = force × distance s A1

(b)

[1]

(ii) as = (v2 – u2) / 2 any subject M1

W = mas hence W = m(v2 – u2) / 2 M1

RHS represents terms of energy or with u = 0 KE = ?mv2 A1

[3]

(i) work done = ? × 1500 × [(30)2 – (15)2] (=506250)C1

(c)

distance = WD / F = 506250 / 3800 = 133m A1 [2]

or F = ma a = 2.533 (m s–2) C1

v2 = u2 + 2as s = 133m A1

(ii) the change in kinetic energy is greater or the work done by the force has to

be greater, hence distance is greater (for same force)A1 [1]

allow: same acceleration, same time, so greater average speed and greater

distance

3 (a) (i) stress = force / (cross-sectional) area B1 [1]

(ii) strain = extension / original length or change in length / original length B1 [1]

(b)

point beyond which material does not return to the original length / shape / size

when the load / force is removed B1 [1]

? University of Cambridge International Examinations 2011

(c)

UTS is the maximum force / original cross-sectional area M1

wire is able to support / before it breaks A1 [2]

allow one: maximum stress the wire is able to support / before it breaks

(i) straight line from (0,0)M1

(d)

correct shape in plastic region A1 [2]

(ii) only a straight line from (0,0)B1 [1]

(i) ductile: initially force proportional to extension then a large extension for

(e)

in

force B1

change

small

brittle: force proportional to extension until it breaks B1 [2]

(ii) 1. does not return to its original length / permanent extension (as entered

plastic region) B1

2. returns to original length / no extension (as no plastic region / still in

elastic region) B1 [2]

4 (a) electric field strength = force / positive charge B1 [1]

(i) at least three equally spaced parallel vertical lines B1

(b)

direction down B1 [2]

(ii) E = 1500 / 20 × 10–3 = 75000V m–1A1 [1]

(iii) F = qE C1

(W = mg and) qE = mg C1

q = mg / E = 5 × 10–15 × 9.81 / 75000

= 6.5 × 10–19C A1 charge A1 [4]

negative

(iv) F > mg or F now greater B1

upwards

move

will

drop

[2]

B1

5 (a) (i) ?1 + ?3 = ?2A1 [1]

(ii) E1 = ?2R2 + ?1R2 + ?1R1+ ?1r1A1 [1]

22

(iii) E1 – E2B1

= –?3r2 + ?1(R1 + r1 + R2 / 2)B1 [2]

p.d. across BJ of wire changes / resistance of BJ changes B1

(b)

there is a difference in p.d across wire and p.d. across cell E2B1 [2]

6 (a) waves overlap B1

(resultant) displacement is the sum of the displacements of each of the waves B1 [2]

? University of Cambridge International Examinations 2011

(b)

waves travelling in opposite directions overlap / incident and reflected waves

overlap

(allow superpose or interfere for overlap here) B1

waves have the same speed and frequency B1 [2]

(i) time period = 4 × 0.1 (ms)C1

(c)

f = 1 / T = 1 / 4 × 10–4 = 2500Hz A1

[2]

(ii) 1. the microphone is at an antinode and goes to a node and then an

antinode / maximum amplitude at antinode and minimum amplitude at

node B1[1]

2. λ/ 2 = 6.7(cm)C1

v = fλ C1

v = 2500 × 13.4 × 10–2 = 335m s–1A1 [3]

incorrect λ then can only score second mark

7 (a) (i) the half life / count rate / rate of decay / activity is the same no matter what

external factors / environmental factors or two named factors such as

temperature and pressure changes are applied B1 [1]

(ii) the observations of the count rate / count rate / rate of decay / activity /

radioactivity during decay shows variations / fluctuations B1 [1]

(b)

property α-particle β-particle γ-radiation

charge (+)2e–e0

mass 4u9.11 × 10–31kg 0

speed 0.01 to 0.1c up to 0.99c c

one mark for each correct line B3 [3]

collision with molecules B1

(c)

causes ionisation (of the molecule) / electron is removed B1 [2]

? University of Cambridge International Examinations 2011

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