9702 m20 QP 22 Merged-1-64

Cambridge International AS & A Level
* 0 7 6 4 3 5 8 0 9 2 *
PHYSICS 9702/22
Paper 2 AS Level Structured Questions February/March 2020
1 hour 15 minutes
You must answer on the question paper.
No additional materials are needed.
INSTRUCTIONS
● Answer all questions.
● Use a black or dark blue pen. You may use an HB pencil for any diagrams or graphs.
● Write your name, centre number and candidate number in the boxes at the top of the page.
● Write your answer to each question in the space provided.
● Do not use an erasable pen or correction fluid.
● Do not write on any bar codes.
● You may use a calculator.
● You should show all your working and use appropriate units.
INFORMATION
● The total mark for this paper is 60.
● The number of marks for each question or part question is shown in brackets [ ].
This document has 16 pages. Blank pages are indicated.
DC (LK/SW) 180016/4
© UCLES 2020 [Turn over
2
Data
speed of light in free space c = 3.00 × 108 m s−1
permeability of free space μ0 = 4π × 10−7 H m−1
permittivity of free space ε0 = 8.85 × 10−12 F m−1

1
( = 8.99 × 109 m F−1)
4πε0
elementary charge e = 1.60 × 10−19 C
the Planck constant h = 6.63 × 10−34 J s
unified atomic mass unit 1 u = 1.66 × 10−27 kg
rest mass of electron me = 9.11 × 10−31 kg
rest mass of proton mp = 1.67 × 10−27 kg
molar gas constant R = 8.31 J K−1 mol−1
the Avogadro constant NA = 6.02 × 1023 mol−1
the Boltzmann constant k = 1.38 × 10−23 J K−1
gravitational constant G = 6.67 × 10−11 N m2 kg−2
acceleration of free fall g = 9.81 m s−2
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Formulae
1
uniformly accelerated motion s = ut + 2 at 2
v 2 = u 2 + 2as
work done on/by a gas W = p ΔV
Gm
gravitational potential φ =−
r
hydrostatic pressure p = ρgh
1 Nm 2
pressure of an ideal gas p = 3 〈c 〉
V
simple harmonic motion a = − ω 2x
velocity of particle in s.h.m. v = v0 cos ωt

v = ± ω (x 02 - x 2)
fsv
Doppler effect fo =
v ± vs
Q
electric potential V =
4πε0r
capacitors in series 1/C = 1/C1 + 1/C2 + . . .
capacitors in parallel C = C1 + C2 + . . .
1
energy of charged capacitor W = 2 QV
electric current I = Anvq
resistors in series R = R1 + R2 + . . .
resistors in parallel 1/R = 1/R1 + 1/R2 + . . .
BI
Hall voltage VH =
ntq
alternating current/voltage x = x0 sin ω t
radioactive decay x = x0 exp(−λt )
0.693
decay constant λ =
t 1
2
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Answer all the questions in the spaces provided.
1 (a) Length, mass and temperature are all SI base quantities.
State two other SI base quantities.
1. ...............................................................................................................................................
2. ...............................................................................................................................................
[2]
(b) The acceleration of free fall g may be determined from an oscillating pendulum using the
equation
4π2l
g=
T2
where l is the length of the pendulum and T is the period of oscillation.
In an experiment, the measured values for an oscillating pendulum are
l = 1.50 m ± 2%
and T = 2.48 s ± 3%.
(i) Calculate the acceleration of free fall g.
g = ................................................ m s–2 [1]
(ii) Determine the percentage uncertainty in g.
percentage uncertainty = ..................................................... % [2]
(iii) Use your answers in (b)(i) and (b)(ii) to determine the absolute uncertainty of the
calculated value of g.
absolute uncertainty = ................................................ m s–2 [1]
[Total: 6]
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6
2 A dolphin is swimming under water at a constant speed of 4.50 m s–1.
(a) The dolphin emits a sound as it swims directly towards a stationary submerged diver. The
frequency of the sound heard by the diver is 9560 Hz. The speed of sound in the water is
1510 m s–1.
Determine the frequency, to three significant figures, of the sound emitted by the dolphin.
frequency = .................................................... Hz [2]
(b) The dolphin strikes the bottom of a floating ball so that the ball rises vertically upwards from
the surface of the water, as illustrated in Fig. 2.1.
path of
ball height of
ball above
ball surface
surface of water
speed 5.6 m s–1
Fig. 2.1
The ball leaves the water surface with speed 5.6 m s–1.
Assume that air resistance is negligible.
(i) Calculate the maximum height reached by the ball above the surface of the water.
height = ..................................................... m [2]
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(ii) The ball leaves the water at time t = 0 and reaches its maximum height at time t = T.
On Fig. 2.2, sketch a graph to show the variation of the speed of the ball with time t from
t = 0 to t = T. Numerical values are not required.
speed
0
0 time t T
Fig. 2.2
[1]
(iii) The mass of the ball is 0.45 kg.
Use your answer in (b)(i) to calculate the change in gravitational potential energy of the
ball as it rises from the surface of the water to its maximum height.
change in gravitational potential energy = ...................................................... J [2]
(iv) State and explain the variation in the magnitude of the acceleration of the ball as it falls
back towards the surface of the water if air resistance is not negligible.
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
..................................................................................................................................... [2]
[Total: 9]

8
3 (a) State what is meant by work done.
...................................................................................................................................................
...................................................................................................................................................
............................................................................................................................................. [1]
(b) A skier is pulled along horizontal ground by a wire attached to a kite, as shown in Fig. 3.1.
wire
kite
speed 4.4 m s–1
140 N
skier 30° ground
horizontal
Fig. 3.1 (not to scale)
The skier moves in a straight line along the ground with a constant speed of 4.4 m s–1. The
wire is at an angle of 30° to the horizontal. The tension in the wire is 140 N.
(i) Calculate the work done by the tension to move the skier for a time of 30 s.
work done = ...................................................... J [3]
(ii) The weight of the skier is 860 N. The vertical component of the tension in the wire and
the weight of the skier combine so that the skier exerts a downward pressure on the
ground of 2400 Pa.
Determine the total area of the skis in contact with the ground.
area = .................................................... m2 [3]
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(iii) The wire attached to the kite is uniform. The stress in the wire is 9.6 × 106 Pa.
Calculate the diameter of the wire.
diameter = ..................................................... m [2]
(c) The variation with extension x of the tension F in the wire in (b) is shown in Fig. 3.2.
300
F/N
250
200
150
100
50
0
0 0.20 0.40 0.60 0.80
x / mm
Fig. 3.2
A gust of wind increases the tension in the wire from 140 N to 210 N.
Calculate the change in the strain energy stored in the wire.
change in strain energy = ...................................................... J [3]
[Total: 12]

10
4 (a) For a progressive wave, state what is meant by:
(i) the wavelength
...........................................................................................................................................
..................................................................................................................................... [1]
(ii) the amplitude.
...........................................................................................................................................
..................................................................................................................................... [1]
(b) A beam of red laser light is incident normally on a diffraction grating.
(i) Diffraction of the light waves occurs at each slit of the grating. The light waves emerging
from the slits are coherent.
Explain what is meant by:
1. diffraction
....................................................................................................................................
.............................................................................................................................. [1]
2. coherent.
....................................................................................................................................
.............................................................................................................................. [1]
(ii) The wavelength of the laser light is 650 nm. The angle between the third order diffraction
maxima is 68°, as illustrated in Fig. 4.1.
third order
diffraction maximum
laser light
68°
wavelength 650 nm
third order
diffraction diffraction maximum
grating
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Calculate the separation d between the centres of adjacent slits of the grating.
d = ..................................................... m [3]
(iii) The red laser light is replaced with blue laser light.
State and explain the change, if any, to the angle between the third order diffraction
maxima.
...........................................................................................................................................
...........................................................................................................................................
..................................................................................................................................... [2]
[Total: 9]

12
5 (a) Define the ohm.
...................................................................................................................................................
...................................................................................................................................................
............................................................................................................................................. [1]
(b) A wire has a resistance of 1.8 Ω. The wire has a uniform cross-sectional area of 0.38 mm2 and
is made of metal of resistivity 9.6 × 10–7 Ω m.
Calculate the length of the wire.
length = ..................................................... m [3]
(c) A resistor X of resistance 1.8 Ω is connected to a resistor Y of resistance 0.60 Ω and a

battery P, as shown in Fig. 5.1.
1.2 V
1.8 Ω 0.60 Ω
X Y
Fig. 5.1
The battery P has an electromotive force (e.m.f.) of 1.2 V and negligible internal resistance.
(i) Explain, in terms of energy, why the potential difference (p.d.) across resistor X is less
than the e.m.f. of the battery.
...........................................................................................................................................
...........................................................................................................................................
..................................................................................................................................... [1]
(ii) Calculate the potential difference across resistor X.
potential difference = ...................................................... V [2]

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(d) Another battery Q of e.m.f. 1.2 V and negligible internal resistance is now connected into the
circuit of Fig. 5.1 to produce the new circuit shown in Fig. 5.2.
1.2 V
Q
1.2 V
1.8 Ω 0.60 Ω
X Y
Fig. 5.2
State whether the addition of battery Q causes the current to decrease, increase or remain
the same in:
(i) resistor X ..................................................................................................................... [1]
(ii) battery P. ..................................................................................................................... [1]
(e) The circuit shown in Fig. 5.2 is modified to produce the new circuit shown in Fig. 5.3.
1.2 V
3.6 Ω
1.8 Ω 0.60 Ω
X Y
Fig. 5.3
Calculate:
(i) the total resistance of the two resistors connected in parallel
resistance = ..................................................... Ω [1]
(ii) the current in resistor Y.
current = ...................................................... A [2]
[Total: 12]

14
6 A uniform electric field is produced between two parallel metal plates. The electric field strength is
1.4 × 104 N C–1. The potential difference between the plates is 350 V.
(a) Calculate the separation of the plates.
separation = ..................................................... m [2]
(b) A nucleus of mass 8.3 × 10–27 kg is now placed in the electric field. The electric force acting
on the nucleus is 6.7 × 10–15 N.
(i) Calculate the charge on the nucleus in terms of e, where e is the elementary charge.
charge = ...................................................... e [3]
(ii) Calculate the mass, in u, of the nucleus.
mass = ...................................................... u [1]
(iii) Use your answers in (b)(i) and (b)(ii) to determine the number of neutrons in the nucleus.
number = ......................................................... [1]
[Total: 7]
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7 (a) State and explain whether a neutron is a fundamental particle.
...................................................................................................................................................
............................................................................................................................................. [1]
(b) A proton in a stationary nucleus decays.
(i) State the two leptons that are produced by the decay.
...........................................................................................................................................
..................................................................................................................................... [2]
(ii) Part of the energy released by the decay is given to the two leptons.
State two possible forms of the remainder of the released energy.
...........................................................................................................................................
..................................................................................................................................... [2]
[Total: 5]
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Cambridge Assessment International Education is part of the Cambridge Assessment Group. Cambridge Assessment is the brand name of the University of
Cambridge Local Examinations Syndicate (UCLES), which itself is a department of the University of Cambridge.
© UCLES 2020 9702/22/F/M/20

* 8 3 9 1 3 2 2 5 3 8 *
PHYSICS 9702/21
Paper 2 AS Level Structured Questions May/June 2020
1 hour 15 minutes
INSTRUCTIONS
INFORMATION
DC (PQ) 181668/3
2
Data

1
( = 8.99 × 109 m F−1)
4πε0
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3
Formulae
1
v 2 = u 2 + 2as
Gm
r
1 Nm 2
V

v = ± ω (x 02 - x 2)
fsv
Doppler effect fo =
v ± vs
Q
4πε0r
1
BI
Hall voltage VH =
ntq
0.693
decay constant λ =
t 1
2
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BLANK PAGE
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1 (a) Use an expression for work done, in terms of force, to show that the SI base units of energy
are kg m2 s–2.
[2]
(b) (i) The energy E stored in an electrical component is given by

Q2
E=
2C
where Q is charge and C is a constant.
Use this equation and the information in (a) to determine the SI base units of C.
SI base units ......................................................... [2]
(ii) Measurements of a constant current in a wire are taken using an analogue ammeter.
For these measurements, describe one possible cause of:
1. a random error
...........................................................................................................................................
...........................................................................................................................................
2. a systematic error.
...........................................................................................................................................
...........................................................................................................................................
[2]
[Total: 6]

6
2 (a) State Newton’s second law of motion.
...................................................................................................................................................
............................................................................................................................................. [1]
(b) A delivery company suggests using a remote-controlled aircraft to drop a parcel into the
garden of a customer. When the aircraft is vertically above point P on the ground, it releases
the parcel with a velocity that is horizontal and of magnitude 5.4 m s–1. The path of the parcel
is shown in Fig. 2.1.
5.4 m s–1
parcel X
path of parcel
h
P Q horizontal
ground
d
The parcel takes a time of 0.81 s after its release to reach point Q on the horizontal ground.
Assume air resistance is negligible.
(i) On Fig. 2.1, draw an arrow from point X to show the direction of the acceleration of the
parcel when it is at that point. [1]
(ii) Determine the height h of the parcel above the ground when it is released.
h = ..................................................... m [2]
(iii) Calculate the horizontal distance d between points P and Q.
d = ..................................................... m [1]
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(c) Another parcel is accidentally released from rest by a different aircraft when it is hovering at a
great height above the ground. Air resistance is now significant.
(i) On Fig. 2.2, draw arrows to show the directions of the forces acting on the parcel as it
falls vertically downwards. Label each arrow with the name of the force.
velocity parcel
Fig. 2.2
[2]
(ii) By considering the forces acting on the parcel, state and explain the variation, if any,
of the acceleration of the parcel as it moves downwards before it reaches constant
(terminal) speed.
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
..................................................................................................................................... [3]
(iii) Describe the energy conversion that occurs when the parcel is falling through the air at
constant (terminal) speed.
...........................................................................................................................................
..................................................................................................................................... [1]
[Total: 11]

8
3 (a) State two conditions for an object to be in equilibrium.
1. ...............................................................................................................................................
...................................................................................................................................................
2. ...............................................................................................................................................
...................................................................................................................................................
[2]
(b) A sphere of weight 2.4 N is suspended by a wire from a fixed point P. A horizontal string is
used to hold the sphere in equilibrium with the wire at an angle of 53° to the horizontal, as
shown in Fig. 3.1.
P
wire
string T
53°
horizontal
F
sphere
weight
2.4 N
(i) Calculate:
1. the tension T in the wire
T = ............................................................ N
2. the force F exerted by the string on the sphere.
F = ............................................................ N
[2]
(ii) The wire has a circular cross-section of diameter 0.50 mm. Determine the stress σ in the
wire.
σ = .................................................... Pa [3]
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9
(c) The string is disconnected from the sphere in (b). The sphere then swings from its initial rest
position A, as illustrated in Fig. 3.2.
75 cm
53°
A
h
The sphere reaches maximum speed when it is at the bottom of the swing at position B. The
distance between P and the centre of the sphere is 75 cm.
Air resistance is negligible and energy losses at P are negligible.
(i) Show that the vertical distance h between A and B is 15 cm.
[1]
(ii) Calculate the change in gravitational potential energy of the sphere as it moves from A
to B.
change in gravitational potential energy = ...................................................... J [2]
(iii) Use your answer in (c)(ii) to determine the speed of the sphere at B.
Show your working.
speed = ................................................ m s–1 [3]
[Total: 13]
10
4 (a) (i) By reference to the direction of propagation of energy, state what is meant by a
longitudinal wave.
...........................................................................................................................................
..................................................................................................................................... [1]
(ii) State the principle of superposition.
...........................................................................................................................................
...........................................................................................................................................
..................................................................................................................................... [2]
(b) The wavelength of light from a laser is determined using the apparatus shown in Fig. 4.1.
double
slit screen
light
3.7 × 10 –4 m
2.3 m
The light from the laser is incident normally on the plane of the double slit.
The separation of the two slits is 3.7 × 10–4 m. The screen is parallel to the plane of the double
slit. The distance between the screen and the double slit is 2.3 m.
A pattern of bright fringes and dark fringes is seen on the screen. The separation of adjacent
bright fringes on the screen is 4.3 × 10–3 m.
(i) Calculate the wavelength, in nm, of the light.
wavelength = ................................................... nm [3]

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(ii) The intensity of the light passing through each slit was initially the same. The intensity of
the light through one of the slits is now reduced.
Compare the appearance of the fringes before and after the change of intensity.
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
..................................................................................................................................... [2]
[Total: 8]

12
5 (a) Metal wire is used to connect a power supply to a lamp. The wire has a total resistance of
3.4 Ω and the metal has a resistivity of 2.6 × 10–8 Ω m. The total length of the wire is 59 m.
(i) Show that the wire has a cross-sectional area of 4.5 × 10–7 m2.
[2]
(ii) The potential difference across the total length of wire is 1.8 V.
Calculate the current in the wire.
current = ...................................................... A [1]
(iii) The number density of the free electrons in the wire is 6.1 × 1028 m–3.
Calculate the average drift speed of the free electrons in the wire.
average drift speed = ................................................ m s–1 [2]
(b) A different wire carries a current. This wire has a part that is thinner than the rest of the wire, as
shown in Fig. 5.1.
wire thinner part
Fig. 5.1
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13
(i) State and explain qualitatively how the average drift speed of the free electrons in the
thinner part compares with that in the rest of the wire.
...........................................................................................................................................
...........................................................................................................................................
..................................................................................................................................... [2]
(ii) State and explain whether the power dissipated in the thinner part is the same, less or
more than the power dissipated in an equal length of the rest of the wire.
...........................................................................................................................................
...........................................................................................................................................
..................................................................................................................................... [2]
(c) Three resistors have resistances of 180 Ω, 90 Ω and 30 Ω.
(i) Sketch a diagram showing how two of these three resistors may be connected together
to give a combined resistance of 60 Ω between the terminals shown.
Ensure you label the values of the resistances in your diagram.
[1]
(ii) A potential divider circuit is produced by connecting the three resistors to a battery of
electromotive force (e.m.f.) 12 V and negligible internal resistance. The potential divider
circuit provides an output potential difference VOUT of 8.0 V.
Fig. 5.2 shows the circuit diagram.
12 V
Fig. 5.2
On Fig. 5.2, label the resistances of all three resistors and the potential
difference VOUT. [2]
[Total: 12]
14
6 (a) Two horizontal metal plates are separated by a distance of 2.0 cm in a vacuum, as shown in
Fig. 6.1.
horizontal
plate
+180 V
2.0 cm
–120 V
horizontal
plate
Fig. 6.1
The top plate has an electric potential of +180 V and the bottom plate has an electric potential
of –120 V.
(i) Determine the magnitude of the electric field strength between the plates.
electric field strength = ............................................... N C–1 [2]
(ii) State the direction of the electric field.
..................................................................................................................................... [1]
238
(b) An uncharged atom of uranium-238 ( 92U) has a change made to its number of orbital
electrons. This causes the atom to change into a new particle (ion) X that has an overall
charge of +2e, where e is the elementary charge.
(i) Determine the number of protons, neutrons and electrons in the particle (ion) X.
number of protons = ...............................................................
number of neutrons = ................................................................
number of electrons = ................................................................

[3]
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(ii) The particle (ion) X is in the electric field in (a) at a point midway between the plates.
Determine the magnitude of the electric force acting on X.
force = ..................................................... N [2]

238
(iii) The nucleus of uranium-238 ( 92U) decays in stages, by emitting α-particles and
230
β– particles, to form a nucleus of thorium-230 ( 90Th).
Calculate the total number of α-particles and the total number of β– particles that are
emitted during the decay of uranium-238 to thorium-230.
number of α-particles = ...............................................................
number of β– particles = ...............................................................

[2]
[Total: 10]
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* 4 6 4 2 4 2 7 0 6 7 *
PHYSICS 9702/22
1 hour 15 minutes
INSTRUCTIONS
INFORMATION
DC (PQ/FC) 181784/2
2
Data

1
( = 8.99 × 109 m F−1)
4πε0
© UCLES 2020 9702/22/M/J/20

3
Formulae

v 2 = u 2 + 2as
work done on/by a gas W = pΔV

Gm
gravitational potential φ=−
r
1 Nm 2
pressure of an ideal gas p= 〈c 〉
3 V

v = ± ω (x 02 - x 2)
fsv
Doppler effect fo =
v ± vs
Q
electric potential V=
4πε0r
1
energy of charged capacitor W= 2
QV

BI
Hall voltage VH =
ntq
alternating current/voltage x = x0 sin ωt
radioactive decay x = x0 exp(−λt)

0.693
decay constant λ= t 1
2

4
BLANK PAGE
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5
1 (a) Define velocity.
...................................................................................................................................................
............................................................................................................................................. [1]
(b) The drag force FD acting on a car moving with speed v along a straight horizontal road is
given by
FD = v 2Ak
where k is a constant and A is the cross-sectional area of the car.
Determine the SI base units of k.
SI base units ......................................................... [2]
(c) The value of k, in SI base units, for the car in (b) is 0.24. The cross-sectional area A of the
car is 5.1 m2.
The car is travelling with a constant speed along a straight road and the output power of the
engine is 4.8 × 104 W. Assume that the output power of the engine is equal to the rate at which
the drag force FD is doing work against the car.
Determine the speed of the car.
speed = ................................................ m s–1 [3]
[Total: 6]

6
2 (a) Fig. 2.1 shows the velocity–time graph for an object moving in a straight line.
v
velocity
0
0 t time
Fig. 2.1
(i) Determine an expression, in terms of u, v and t, for the area under the graph.
area = .......................................................... [1]
(ii) State the name of the quantity represented by the area under the graph.
..................................................................................................................................... [1]
(b) A ball is kicked with a velocity of 15 m s–1 at an angle of 60° to horizontal ground. The ball
then strikes a vertical wall at the instant when the path of the ball becomes horizontal, as
shown in Fig. 2.2.
path of
ball
vertical
velocity wall
15 m s–1
ball
60°
horizontal
ground
Assume that air resistance is negligible.
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7
(i) By considering the vertical motion of the ball, calculate the time it takes to reach the wall.
time = ...................................................... s [3]
(ii) Explain why the horizontal component of the velocity of the ball remains constant as it
moves to the wall.
...........................................................................................................................................
..................................................................................................................................... [1]
(iii) Show that the ball strikes the wall with a horizontal velocity of 7.5 m s–1.
[1]
(c) The mass of the ball in (b) is 0.40 kg. It is in contact with the wall for a time of 0.12 s and
rebounds horizontally with a speed of 4.3 m s–1.
(i) Use the information from (b)(iii) to calculate the change in momentum of the ball due to
the collision.
change in momentum = ........................................... kg m s–1 [2]
(ii) Calculate the magnitude of the average force exerted on the ball by the wall.
average force = ..................................................... N [1]
[Total: 10]

8
3 (a) Explain what is meant by work done.
...................................................................................................................................................
............................................................................................................................................. [1]
(b) A ball of mass 0.42 kg is dropped from the top of a building. The ball falls from rest through
a vertical distance of 78 m to the ground. Air resistance is significant so that the ball reaches
constant (terminal) velocity before hitting the ground. The ball hits the ground with a speed
of 23 m s–1.
(i) Calculate, for the ball falling from the top of the building to the ground:
1. the decrease in gravitational potential energy
decrease in gravitational potential energy = ...................................................... J [2]
2. the increase in kinetic energy.
increase in kinetic energy = ...................................................... J [2]
(ii) Use your answers in (b)(i) to determine the average resistive force acting on the ball as
it falls from the top of the building to the ground.
average resistive force = ..................................................... N [2]
© UCLES 2020 9702/22/M/J/20

9
(c) The ball in (b) is dropped at time t = 0 and hits the ground at time t = T. The acceleration of
free fall is g.
On Fig. 3.1, sketch a line to show the variation of the acceleration a of the ball with time t from
time t = 0 to t = T.
0
0 T
t
Fig. 3.1
[2]
[Total: 9]

10
4 (a) State the difference between progressive waves and stationary waves in terms of the transfer
of energy along the wave.
...................................................................................................................................................
............................................................................................................................................. [1]
(b) A progressive wave travels from left to right along a stretched string. Fig. 4.1 shows part of
the string at one instant.
R direction of
wave travel
Q
P
string
0.48 m
Fig. 4.1
P, Q and R are three different points on the string. The distance between P and R is 0.48 m.
The wave has a period of 0.020 s.
(i) Use Fig. 4.1 to determine the wavelength of the wave.
wavelength = ..................................................... m [1]
(ii) Calculate the speed of the wave.
speed = ................................................ m s–1 [2]
(iii) Determine the phase difference between points Q and R.
phase difference = ........................................................ ° [1]
© UCLES 2020 9702/22/M/J/20

11
(iv) Fig. 4.1 shows the position of the string at time t = 0. Describe how the displacement of
point Q on the string varies with time from t = 0 to t = 0.010 s.
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
..................................................................................................................................... [2]
(c) A stationary wave is formed on a different string that is stretched between two fixed points
X and Y. Fig. 4.2 shows the position of the string when each point is at its maximum
displacement.
X Y
Z
Fig. 4.2
(i) Explain what is meant by a node of a stationary wave.
..................................................................................................................................... [1]
(ii) State the number of antinodes of the wave shown in Fig. 4.2.
number = ......................................................... [1]
(iii) State the phase difference between points W and Z on the string.
phase difference = ........................................................° [1]
(iv) A new stationary wave is now formed on the string. The new wave has a frequency
that is half of the frequency of the wave shown in Fig. 4.2. The speed of the wave is
unchanged.
On Fig. 4.3, draw a position of the string, for this new wave, when each point is at its
maximum displacement.
X Y
Fig. 4.3
[1]
[Total: 11]
12
5 One end of a wire is attached to a fixed point. A force F is applied to the wire to cause extension x.
The variation with F of x is shown in Fig. 5.1.
0.6
0.5
x / mm
0.4
0.3
0.2
0.1
0
0 5 10 15 20 25 30 35 40 45
F/N
Fig. 5.1
The wire has a cross-sectional area of 4.1 × 10–7 m2 and is made of metal of Young modulus
1.7 × 1011 Pa. Assume that the cross-sectional area of the wire remains constant as the wire
extends.
(a) State the name of the law that describes the relationship between F and x shown in Fig. 5.1.
............................................................................................................................................. [1]
(b) The wire has an extension of 0.48 mm.
Determine:
(i) the stress
stress = .................................................... Pa [2]
(ii) the strain.
strain = ......................................................... [2]
© UCLES 2020 9702/22/M/J/20

13
(c) The resistivity of the metal of the wire is 3.7 × 10–7 Ω m.
Determine the change in resistance of the wire when the extension x of the wire changes
from x = 0.48 mm to x = 0.60 mm.
change in resistance = ..................................................... Ω [3]
(d) A force of greater than 45 N is now applied to the wire.
Describe how it may be checked that the elastic limit of the wire has not been exceeded.
...................................................................................................................................................
............................................................................................................................................. [1]
[Total: 9]

14
6 (a) A battery of electromotive force (e.m.f.) 7.8 V and internal resistance r is connected to a
filament lamp, as shown in Fig. 6.1.
7.8 V
r
Fig. 6.1
A total charge of 750 C moves through the battery in a time interval of 1500 s. During this time
the filament lamp dissipates 5.7 kJ of energy. The e.m.f. of the battery remains constant.
(i) Explain, in terms of energy and without a calculation, why the potential difference across
the lamp must be less than the e.m.f. of the battery.
...........................................................................................................................................
..................................................................................................................................... [1]
(ii) Calculate:
1. the current in the circuit
current = ...................................................... A [2]
2. the potential difference across the lamp
3. the internal resistance of the battery.
internal resistance = ...................................................... Ω [2]

© UCLES 2020 9702/22/M/J/20
15
(b) A student is provided with three resistors of resistances 90 Ω, 45 Ω and 20 Ω.
(i) Sketch a circuit diagram showing how two of these three resistors may be connected
together to give a combined resistance of 30 Ω between the terminals shown. Label the
values of the resistances on your diagram.
[1]
(ii) A potential divider circuit is produced by connecting the three resistors to a battery of
e.m.f. 9.0 V and negligible internal resistance. The potential divider circuit provides an
output potential difference VOUT of 3.6 V. The circuit diagram is shown in Fig. 6.2.
9.0 V
Fig. 6.2
On Fig. 6.2, label the resistances of all three resistors and the potential difference VOUT.
[2]
[Total: 10]

16
7 (a) A nucleus of an element X decays by emitting a β+ particle to produce a nucleus of

39
potassium-39 (19K) and a neutrino. The decay is represented by
Q 39
SX 19K + RP β+ + 00ν.
(i) State the number represented by each of the following letters.
P ..............................
Q ..............................
R ..............................
S ..............................
[2]
(ii) State the name of the interaction (force) that gives rise to β+ decay.
..................................................................................................................................... [1]
(b) A hadron is composed of three identical quarks and has a charge of +2e, where e is the
elementary charge.
Determine a possible type (flavour) of the quarks.

Explain your working.
...................................................................................................................................................
............................................................................................................................................. [2]
[Total: 5]
© UCLES 2020 9702/22/M/J/20

* 1 1 0 0 0 9 6 8 3 7 *
PHYSICS 9702/23
1 hour 15 minutes
INSTRUCTIONS
INFORMATION
DC (SC/FC) 181785/2
2
Data

1
( = 8.99 × 109 m F−1)
4πε0
© UCLES 2020 9702/23/M/J/20

3
Formulae
1
v 2 = u 2 + 2as
Gm
r
1 Nm 2
V

v = ± ω (x 02 - x 2)
fsv
Doppler effect fo =
v ± vs
Q
4πε0r
1
BI
Hall voltage VH =
ntq
0.693
decay constant λ =
t 1
2

4
BLANK PAGE
© UCLES 2020 9702/23/M/J/20

5
1 (a) State one similarity and one difference between distance and displacement.
similarity: ...................................................................................................................................
...................................................................................................................................................
difference: .................................................................................................................................
...................................................................................................................................................
[2]
(b) A student takes several measurements of the same quantity. This set of measurements has
high precision, but low accuracy.
Describe what is meant by:
(i) high precision
...........................................................................................................................................
..................................................................................................................................... [1]
(ii) low accuracy.
...........................................................................................................................................
..................................................................................................................................... [1]
[Total: 4]

6
2 (a) State Newton’s first law of motion.
...................................................................................................................................................
............................................................................................................................................. [1]
(b) A skier is pulled in a straight line along horizontal ground by a wire attached to a kite, as
shown in Fig. 2.1.
kite
wire
skier
mass 89 kg
28°
horizontal
ground
The mass of the skier is 89 kg. The wire is at an angle of 28° to the horizontal. The variation
with time t of the velocity v of the skier is shown in Fig. 2.2.
5.0
4.0
v / m s–1
3.0
2.0
1.0
0
0 1.0 2.0 3.0 4.0 5.0
t/s
Fig. 2.2
(i) Use Fig. 2.2 to determine the distance moved by the skier from time t = 0 to t = 5.0 s.
distance = ..................................................... m [2]
© UCLES 2020 9702/23/M/J/20

7
(ii) Use Fig. 2.2 to show that the acceleration a of the skier is 0.80 m s–2 at time t = 2.0 s.
[2]
(iii) The tension in the wire at time t = 2.0 s is 240 N.
Calculate:
1. the horizontal component of the tension force acting on the skier
horizontal component of force = ..................................................... N [1]
2. the total resistive force R acting on the skier in the horizontal direction.
R = ..................................................... N [2]
(iv) The skier is now lifted upwards by a gust of wind. For a few seconds the skier moves
horizontally through the air with the wire at an angle of 45° to the horizontal, as shown
in Fig. 2.3.
45°
horizontal
By considering the vertical components of the forces acting on the skier, determine the
new tension in the wire when the skier is moving horizontally through the air.
tension = ..................................................... N [2]

[Total: 10]
8
3 (a) State the principle of moments.
...................................................................................................................................................
...................................................................................................................................................
............................................................................................................................................. [2]
(b) In a bicycle shop, two wheels hang from a horizontal uniform rod AC, as shown in Fig. 3.1.
ceiling
cord
0.45 m 1.40 m 0.75 m
22 N
wall
A B C
wheel wheel
W 19 N W
The rod has weight 19 N and is freely hinged to a wall at end A. The other end C of the rod is
attached by a vertical elastic cord to the ceiling. The centre of gravity of the rod is at point B.
The weight of each wheel is W and the tension in the cord is 22 N.
(i) By taking moments about end A, show that the weight W of each wheel is 14 N.
[2]
(ii) Determine the magnitude and the direction of the force acting on the rod at end A.
magnitude = ........................................................... N
direction ...............................................................
[2]
© UCLES 2020 9702/23/M/J/20

9
(c) The unstretched length of the cord in (b) is 0.25 m. The variation with length L of the tension F
in the cord is shown in Fig. 3.2.
60
50
F/N
40
30
20
10
0
0 0.25 0.50 0.75 1.00
L/m
Fig. 3.2
(i) State and explain whether Fig. 3.2 suggests that the cord obeys Hooke’s law.
...........................................................................................................................................
...........................................................................................................................................
..................................................................................................................................... [2]
(ii) Calculate the spring constant k of the cord.
k = ............................................... N m–1 [2]
(iii) On Fig. 3.2, shade the area that represents the work done to extend the cord when the
tension is increased from F = 0 to F = 40 N. [1]
[Total: 11]

10
4 Two progressive sound waves Y and Z meet at a fixed point P. The variation with time t of the
displacement x of each wave at point P is shown in Fig. 4.1.
4 wave Y
x / μm
2
0
0 1.0 2.0 3.0 t / ms 4.0
–2
wave Z
–4
–6
Fig. 4.1
(a) Use Fig. 4.1 to state one quantity of waves Y and Z that is:
(i) the same
..................................................................................................................................... [1]
(ii) different.
..................................................................................................................................... [1]
(b) State and explain whether waves Y and Z are coherent.
...................................................................................................................................................
............................................................................................................................................. [1]
(c) Determine the phase difference between the waves.
phase difference = ....................................................... ° [1]
(d) The two waves superpose at P. Use Fig. 4.1 to determine the resultant displacement at time
t = 0.75 ms.
resultant displacement = ................................................... μm [1]
© UCLES 2020 9702/23/M/J/20

11
(e) The intensity of wave Y at point P is I.
Determine, in terms of I, the intensity of wave Z.
intensity = ......................................................... [2]
(f) The speed of wave Z is 330 m s–1.
Determine the wavelength of wave Z.
wavelength = ..................................................... m [3]
[Total: 10]

12
5 (a) Define the volt.
...................................................................................................................................................
............................................................................................................................................. [1]
(b) Fig. 5.1 shows a network of three resistors.
300 Ω
55 Ω
X Y
100 Ω
Fig. 5.1
Calculate:
(i) the combined resistance of the two resistors connected in parallel
combined resistance = ..................................................... Ω [1]
(ii) the total resistance between terminals X and Y.
total resistance = ..................................................... Ω [1]
(c) The network in (b) is connected to a power supply so that there is a potential difference
between terminals X and Y. The power dissipated in the resistor of resistance 55 Ω is 0.20 W.
(i) Calculate the current in the resistor of resistance:
1. 55 Ω
current = ............................................................ A
2. 300 Ω.
current = ............................................................ A
[3]
© UCLES 2020 9702/23/M/J/20

13
(ii) Calculate the potential difference between X and Y.
[Total: 7]

14
6 The current I in a metal wire is given by the expression
I = Anve
where v is the average drift speed of the free electrons in the wire and e is the elementary charge.
(a) State what is meant by the symbols A and n.
A: ..............................................................................................................................................
n: ...............................................................................................................................................
[2]
(b) Use the above expression to determine the SI base units of e.

Show your working.
base units ......................................................... [2]
(c) Two lamps P and Q are connected in series to a battery, as shown in Fig. 6.1.
P Q
Fig. 6.1
The radius of the filament wire of lamp P is twice the radius of the filament wire of lamp Q.
The filament wires are made of metals with the same value of n.
Calculate the ratio
average drift speed of free electrons in filament wire of P .

average drift speed of free electrons in filament wire of Q
ratio = ......................................................... [2]
[Total: 6]
© UCLES 2020 9702/23/M/J/20

15
7 A potential difference is applied between two horizontal metal plates that are a distance of 6.0 mm
apart in a vacuum, as shown in Fig. 7.1.
horizontal
– 450 V
plate
6.0 mm path of β– particle
horizontal radioactive 0V
plate source
Fig. 7.1
The top plate has a potential of –450 V and the bottom plate is earthed. Assume that there is a
uniform electric field produced between the plates.
A radioactive source emits a β– particle that travels through a hole in the bottom plate and along a
vertical path until it reaches the top plate.
(a) (i) Determine the magnitude and the direction of the electric force acting on the β– particle
as it moves between the plates.
magnitude of force = ........................................................... N
direction of force ...............................................................

[4]
(ii) Calculate the work done by the electric field on the β– particle for its movement from the
bottom plate to the top plate.
work done = ...................................................... J [2]

16
(b) The β– particle is emitted from the source with a kinetic energy of 3.4 × 10–16 J.
Calculate the speed at which the β– particle is emitted.
speed = ................................................ m s–1 [2]
(c) The β– particle is produced by the decay of a neutron.
(i) Complete the equation below to represent the decay of the neutron.
1
0 n 0
–1 β– + ........ .........
........
+ ........ .........
........ [2]
(ii) State the name of the group (class) of particles that includes:
1. neutrons
....................................................................................................................................
2. β– particles.
....................................................................................................................................
[2]
[Total: 12]
© UCLES 2020 9702/23/M/J/20

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Cambridge International AS & A Level

You must answer on the question paper.

No additional materials are needed.

This document has 16 pages. Blank pages are indicated.

speed of light in free space c = 3.00 × 108 m s−1

permeability of free space μ0 = 4π × 10−7 H m−1

permittivity of free space ε0 = 8.85 × 10−12 F m−1

the Planck constant h = 6.63 × 10−34 J s

unified atomic mass unit 1 u = 1.66 × 10−27 kg

rest mass of electron me = 9.11 × 10−31 kg

rest mass of proton mp = 1.67 × 10−27 kg

molar gas constant R = 8.31 J K−1 mol−1

the Avogadro constant NA = 6.02 × 1023 mol−1

the Boltzmann constant k = 1.38 × 10−23 J K−1

gravitational constant G = 6.67 × 10−11 N m2 kg−2

acceleration of free fall g = 9.81 m s−2

© UCLES 2020 9702/22/F/M/20

work done on/by a gas W = p ΔV

hydrostatic pressure p = ρgh

velocity of particle in s.h.m. v = v0 cos ωt

capacitors in series 1/C = 1/C1 + 1/C2 + . . .

electric current I = Anvq

resistors in parallel 1/R = 1/R1 + 1/R2 + . . .

alternating current/voltage x = x0 sin ω t

radioactive decay x = x0 exp(−λt )

© UCLES 2020 9702/22/F/M/20 [Turn over

Answer all the questions in the spaces provided.

1 (a) Length, mass and temperature are all SI base quantities.

State two other SI base quantities.

In an experiment, the measured values for an oscillating pendulum are

(i) Calculate the acceleration of free fall g.

g = ................................................ m s–2 [1]

(ii) Determine the percentage uncertainty in g.

percentage uncertainty = ..................................................... % [2]

absolute uncertainty = ................................................ m s–2 [1]

© UCLES 2020 9702/22/F/M/20

© UCLES 2020 9702/22/F/M/20 [Turn over

2 A dolphin is swimming under water at a constant speed of 4.50 m s–1.

frequency = .................................................... Hz [2]

Assume that air resistance is negligible.

height = ..................................................... m [2]

© UCLES 2020 9702/22/F/M/20

(iii) The mass of the ball is 0.45 kg.

change in gravitational potential energy = ...................................................... J [2]

© UCLES 2020 9702/22/F/M/20 [Turn over

3 (a) State what is meant by work done.

Fig. 3.1 (not to scale)

work done = ...................................................... J [3]

area = .................................................... m2 [3]

© UCLES 2020 9702/22/F/M/20

Calculate the diameter of the wire.

diameter = ..................................................... m [2]

Calculate the change in the strain energy stored in the wire.

change in strain energy = ...................................................... J [3]

© UCLES 2020 9702/22/F/M/20 [Turn over

4 (a) For a progressive wave, state what is meant by:

(i) the wavelength