Cambridge International Examinations Cambridge ...

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Cambridge International Examinations Cambridge International Advanced Subsidiary and Advanced Level

PHYSICS Paper 2 AS Structured Questions

Candidates answer on the Question Paper. No Additional Materials are required.

9702/21 May/June 2015

1 hour

READ THESE INSTRUCTIONS FIRST

Write your Centre number, candidate number and name on all the work you hand in. Write in dark blue or black pen. You may use an HB pencil for any diagrams or graphs. Do not use staples, paper clips, glue or correction fluid. DO NOT WRITE IN ANY BARCODES.

Answer all questions.

Electronic calculators may be used. You may lose marks if you do not show your working or if you do not use appropriate units.

At the end of the examination, fasten all your work securely together. The number of marks is given in brackets [ ] at the end of each question or part question.

DC (LK) 92821/2 ? UCLES 2015

This document consists of 16 printed pages.

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Data speed of light in free space, permeability of free space, permittivity of free space,

elementary charge, the Planck constant, unified atomic mass constant, rest mass of electron, rest mass of proton, molar gas constant, the Avogadro constant, the Boltzmann constant, gravitational constant, acceleration of free fall,

2

c = 3.00 ? 108 m s?1

0 = 4 ? 10?7 H m?1

0 = 8.85 ? 10?12 F m?1

(

1

40

= 8.99 ? 109 m F?1)

e = 1.60 ? 10?19 C

h = 6.63 ? 10?34 J s

u = 1.66 ? 10?27 kg

me = 9.11 ? 10?31 kg mp = 1.67 ? 10?27 kg

R = 8.31 J K?1 mol?1

NA = 6.02 ? 1023 mol?1 k = 1.38 ? 10?23 J K?1

G = 6.67 ? 10?11 N m2 kg?2

g = 9.81 m s?2

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Formulae uniformly accelerated motion,

work done on/by a gas, gravitational potential, hydrostatic pressure, pressure of an ideal gas, simple harmonic motion, velocity of particle in s.h.m.,

electric potential, capacitors in series, capacitors in parallel, energy of charged capacitor, resistors in series, resistors in parallel, alternating current/voltage, radioactive decay, decay constant,

3

s = ut + at 2 v 2 = u 2 + 2as

W = pV

=

?

Gm r

p = gh

p = Nm V

a = ? 2x

v = v0 cos t

v = ? ( x 02 ? x 2 )

V

=

Q

40r

1/C = 1/C1 + 1/C2 + . . .

C = C1 + C2 + . . .

W = QV

R = R1 + R2 + . . .

1/R = 1/R1 + 1/R2 + . . .

x = x0 sin t

x = x0 exp(?t)

=

0.693 t

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4 Answer all the questions in the spaces provided. 1 (a) Use the definition of power to show that the SI base units of power are kg m2 s?3.

[2] (b) Use an expression for electrical power to determine the SI base units of potential difference.

units ...........................................................[2]

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5 2 (a) Define speed and velocity and use these definitions to explain why one of these quantities is

a scalar and the other is a vector.

speed: ......................................................................................................................................

velocity: .....................................................................................................................................

...................................................................................................................................................

................................................................................................................................................... [2]

(b) A ball is released from rest and falls vertically. The ball hits the ground and rebounds vertically, as shown in Fig. 2.1.

initial position ball

rebound Fig. 2.1

ground

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6 The variation with time t of the velocity v of the ball is shown in Fig. 2.2.

12.0

10.0

8.0 v / m s?1

6.0

4.0

2.0

0 0

? 2.0

1.0

2.0

3.0

t / s

? 4.0

? 6.0 ? 8.0

? 10.0

Fig. 2.2

Air resistance is negligible.

(i) Without calculation, use Fig. 2.2 to describe the variation with time t of the velocity of the ball from t = 0 to t = 2.1 s.

...........................................................................................................................................

...........................................................................................................................................

...........................................................................................................................................

...........................................................................................................................................

...........................................................................................................................................

.......................................................................................................................................[3]

(ii) Calculate the acceleration of the ball after it rebounds from the ground. Show your working.

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acceleration = ................................................. m s?2 [3]

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7 (iii) Calculate, for the ball, from t = 0 to t = 2.1 s,

1. the distance moved,

distance = ...................................................... m [3] 2. the displacement from the initial position.

displacement = ...................................................... m [2] (iv) On Fig. 2.3, sketch the variation with t of the speed of the ball.

12.0

10.0

8.0 speed / m s?1

6.0

4.0

2.0

0 0

? 2.0

1.0

2.0

3.0

t / s

? 4.0

? 6.0 ? 8.0

? 10.0

Fig. 2.3 [2]

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8 3 Two balls X and Y are supported by long strings, as shown in Fig. 3.1.

X

Y

4.5 m s?1 2.8 m s?1

Fig. 3.1

The balls are each pulled back and pushed towards each other. When the balls collide at the position shown in Fig. 3.1, the strings are vertical. The balls rebound in opposite directions.

Fig. 3.2 shows data for X and Y during this collision.

ball

mass

velocity just before

velocity just after

collision / m s?1

collision / m s?1

X

50 g

+4.5

?1.8

Y

M

?2.8

+1.4

Fig. 3.2 The positive direction is horizontal and to the right. (a) Use the conservation of linear momentum to determine the mass M of Y.

M = ....................................................... g [3]

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