Download Physics Practice Paper 1 - TWGHs. Kap Yan Directors` College

Tung Wah Group of Hospitals Kap Yan Directors' College
Physics Practice Paper for HKDSE
6D
Time : 1 hour
Full mark : 45
LPK
Take g = 10 m s-2 if necessary.
1. A boy riding a bicycle travels up a hill at a constant speed of 4 m s-1 and returns down the hill at a
constant speed of 6 m s-1. What is his average speed for the whole journey?
A. 2.4 m s-1
B. 4.8 m s-1 *
C. 5.0 m s-1
D. Cannot be determined because the times for upward and downward journey are not given.
2. A uniform heavy rope of weight 100 N hangs from a hook as shown. A
box of 50 N hangs from the rope. What is the tension in the rope?
A.
B.
C.
D.
Rope of
weight 100 N
50 N throughout the rope.
100 N throughout the rope.
150 N throughout the rope.
It varies from 50 N at the bottom of the rope to 150 N at the
top. *
3. Three forces X, Y and Z act on a particle P which is originally at
rest as shown in the figure. The particle P will
A.
B.
C.
D.
accelerate in the direction along X. *
move with constant velocity in the direction along X.
remain at rest.
accelerate in the direction opposite to X.
4. A person standing with two feet on a bathroom scale reads a weight on the dial. What would happen
immediately to the scale reading in the following two situations:
(1) He lifts one foot into the air, thereby only supporting himself on half the area compared to before.
(2) He throws an object downward.
(1) lifting one foot
A.
B.
C.
D.
(2) throwing an object downward
unchanged
unchanged
unchanged
decreased
unchanged
increased
decreased *
increased
5. A plane is travelling in the air at constant velocity.
Which of the following figures best represents the
component forces (represented by arrows) acting on
the plane at X travelling to the right? (The length of
arrow corresponds to the magnitude of the force)
****
6. A particle is fired at an angle of 30º to the horizontal with a speed of 50 m s–1. A physics teacher takes
a photo at t = 2 s, how high is the particle above the ground?
A.
28 m
B. 30 m *
C. 32 m
D. 34 m
7. A motor car of mass 2 500 kg accelerates from rest to a speed of 20 m s1 in 5 s on a level road. Find
the average power of the car.
A.
5 kW
B. 25 kW
C. 75 kW
D. 100 kW *
8. A ball is kicked by a player and the variation of force F exerted on
the ball with impact time t is shown. Find the change in momentum
of the ball in kg m s–1.
A.
0
B. 0.1
C. 0.2
P.1
D. 0.5 *
9. The figure shows a circular space station. Suppose the radius of the station is
1 km. What should be the rotational speed to give astronauts working in the
rims of the station an artificial gravity similar to what we feel on the earth?
The answer is expressed in terms of rev s–1.
A.
0.0 069 rev s–1
B. 0.0 159 rev s–1 *
C.
0.0 199 rev s–1
D. 0.0 259 rev s–1
10. As shown in the figure, the image of the lamp is not formed exactly on
the screen. Which of the following methods can produce a sharp image
of the lamp on the screen ?
(1) Place another convex lens between the object and the screen.
(2) Move the lamp closer to the lens.
(3) Move the screen towards the lens.
A. (1) only
B. (2) only
C. (1) and (2) only
D. (2) and (3) only *
11. The frequency of infrared radiation is less than all of the following except
A. visible light
B. radio waves * C. ultraviolet light
D. X-rays
12. The figure shows a vibrator generating stationary wave on a string.
At the instant shown, the string is at its maximum displacement.
Which of the following statements is/are correct ?
(1) P is a node.
(2) Q is moving downward while S is moving upward.
(3) PT is half a wavelength.
A. (1) only
B. (2) only
C. (1) and (3) only *
D. (2) and (3) only
13. Water waves of wavelength 4 cm are produced by two vibrators X and Y, placed
4 cm apart. Each vibrator, when operated by itself, produces waves which have
an amplitude A at P which is 3 cm from X as shown in the figure. When the
vibrators are operating exactly out of phase, the amplitude of oscillation at P is
A. 0
B. 0.5 A
C. A
D. 2A *
14. Figure (a) shows a CRO trace of a note produced by a tuning
fork. The Y-gain setting of the CRO is 0.5 V div-1. In Figure
(b), the amplitude is double that in Figure (a). Which of the
following can change the trace to Figure (b)?
Figure (a)
(1) Use a tuning fork of higher frequency.
(2) Produce a louder note.
(3) Change the Y-gain setting to 0.25 V div-1.
A. (1) only
C. (1) and (3) only
Figure (b)
B. (2) only
D. (2) and (3) only *
15. Which of the following statements about interference is/are correct?
(1) Constructive interference always occurs at a point where the path difference is zero.
(2) For water waves, destructive interference always occurs at a point where crest meets trough.
(3) For water waves, the point where constructive interference takes place is always bright.
A. (1) only
C. (1) and (3) only
B. (2) only *
D. (2) and (3) only
16. The figure shows a wave pattern due to an optical phenomenon. The black line
is a dark fringe and the white line is a bright fringe. Which of the following
is/are correct?
(1) The formation of the wave pattern is due to diffraction.
(2) At a bright fringe, constructive interference takes place.
(3) The separation between the fringes increases when the slit-to-screen distance increases.
A. (1) only
B. (2) only
C. (1) and (3) only
P.2
D. (2) and (3) only *
17. Which of the following is/are application(s) of ultrasonic?
(1) Measurement of the depth of the sea
(2) Detection of flaws in a railway track
(3) Cleaning of jewels
A. (1) and (3) only
B. (1) and (2) only
C. (2) and (3) only
D. (1), (2) and (3)*
18. Light of wavelength 650 nm is incident normally on a plane diffraction grating having a ruling of
5500 lines per cm. Determine the diffraction angle for the second order of fringe.
A.
43.6º
B. 44.6º
C. 45.6º *
D. 46.6º
19. Identical containers A and B contain oxygen (O2) and hydrogen (H2)
respectively. Both gases are at room temperature and atmospheric
pressure. Which of the following statements is/are true?
In both containers,
(1) the number of gas molecules is the same;
(2) the root mean square speed of H2 molecules is higher than that of
O2 molecules;
(3) the frequency of collision of gas molecules with the walls of container is the same.
A. (1) only
B. (3) only
C. (1) and (2) only *
D. (2) and (3) only
20. A hydrogen gas jar of pressure 140 x 105 Pa and volume 10-2 m3 is used to
fill hydrogen balloons of volume 4 x 10-3 m3 each at 1.1 x 105 Pa. Assume
that after filling up balloons, the pressure of the gas jar drops to zero. The
number of balloons that can be filled is
A. 300
B. 318 *
C. 336
D. 354
21. An ice-making machine extracts energy at a rate of 500 W. The specific latent heat of fusion of ice is
300 kJ kg-1. How long does it take to freeze 2 kg of water at 0oC?
A. 1.2 s
B. 3.3 s
C. 300 s
D. 1200 s *
22. A kettle of water is heated on top of a gas stove. Which of the following statements about the transfer
of heat occurring are correct?
(1) Heat is transferred from the flame to the water by conduction.
(2) Heat is transferred within the water by convection.
(3) Heat is transferred from the flame to the surroundings by conduction and radiation.
A. (1) and (2) only *
B. (1) and (3) only
C. (2) and (3) only
D. (1), (2) and (3)
23. Two objects are heated by two heaters of the same power for the same time interval. Which of the
following are true?
(1) The same amount of heat is transferred to the two objects.
(2) The two objects have the same increase in internal energy.
(3) The two objects have the same rise in temperature.
A. (1) and (2) only *
B. (1) and (3) only
C. (2) and (3) only
D. (1), (2) and (3)
24. The diagram shows a uniform electric field in which
the lines of equal potential are spaced 2.0 cm apart.
What is the value of the electric force which is
exerted on a charge of +5.0μC when placed in the
field?
A. 6.0 ×10-6 N
B. 1.5 ×10-2 N *
C. 3.0 ×103 N
D. 6.0 ×108 N
25. Two metal balls A and B have equal radii and same quantity of charges. Let the attractive force
between them be F. The other metal ball which has an equal radius but carries no charges touches A
and then B, and moves away. Find the force between A and B.
A.
1
F*
8
B.
1
F
4
C.
3
F
8
P.3
D. 0
26. A negative charge moves in an electric field with uniformly accelerating linear motion from rest. The
charge moves from point A to point B under the electric force. The electric field strengths at A and B
are EA and EB, and the electric potential of the charge at A and B are VA and VB respectively. Which of
the following descriptions is correct?
(1) EA = EB
(2) The speed of the charge at A is smaller than that at B.
(3) VA > VB
A. (1) only
B. (3) only
C. (1) and (2) only *
D. (2) and (3) only
27. The figure shows a circuit. Find the electrical power delivered by the cell.
A.
3W
B.
6W
C.
7.5 W *
D.
It cannot be determined since R is unknown.
28. The circuit is used to measure the resistance of a wire.
Which of the following statements is/are correct?
(1) The circuit is more suitable to measure small resistance.
(2) If the slider of the rheostat is moved to the end P, the
current passing through the wire will be smaller.
(3) The ammeter measures the total current flowing through
the wire and the voltmeter.
A. (1) only
C. (1) and (3) only *
B. (2) only
D. (2) and (3) only
29. A long wire carries a current in the direction shown. Which of
the following figures correctly show(s) the direction of the
compass needle ?
A. (1) only
B. (2) only *
C. (1) and (3) only
D. (2) and (3) only
30. As shown in the figure, the square abcd is in a uniform magnetic field. A
hydrogen nucleus is injected into the magnetic field at certain speed from the
middle point m on the edge ad. The direction of the hydrogen nucleus is
perpendicular to the edge ad and the magnetic field. The hydrogen nucleus is
emitted from the magnetic field from the middle point n on the edge ab. With
other conditions unchanged, if the magnetic field strength becomes twice of
the original, what is the position at which the hydrogen nucleus emits from
the magnetic field?
A.
C.
point b
point a
B. a point between n and a
D. a point between a and m
31. A wire AB is moving across a magnetic field as shown. Which of
the following statements is/are correct?
(1) Current flows from A to B inside the wire.
(2) End A is at a higher potential than end B.
(3) The potential difference between A and B will be larger if the
wire is moving faster.
A. (2) only
B. (3) only
C. (1) and (3) only
P.4
D. (2) and (3) only *
32.
The figure shows a model transmission system. An a.c. supply and two ideal transformers are used to
operate a lamp of rating '6V, 24 W'. The total resistance of the cables AB and CD is 10 . If the lamp
operates at its rated value, find the power loss in the cables.
A. 0.4 W *
33.
B. 3.6 W
C. 160 W
D. 1440 W
238
92 U
decays through a series of transformations to a final stable nuclide. The particles emitted in the
successive transformations are αββαα. Which nuclide is not produced during this series of
transformations?
A. 228
B. 230
C. 234
D. 234
88 Ra *
90 Th
91 Pa
92 U
34. The half-life of a certain radioactive isotope is 32 hours. What fraction of a sample would remain
after 16 hours?
A. 0.29
B. 0.50
C 0.71*
D. 0.75
35. The half-lives of three nuclides are:
cobalt-60
strontium-90
carbon-14
5.3 years
28 years
5600 years
Which of the following statements about samples of these nuclides is/are correct?
(1) If pure samples having the same activity at that moment are taken, there will be more atoms of
carbon-14 than of either strontium-90 or cobalt-60 in the respective samples.
(2) If samples containing equal numbers of atoms of each of these nuclides are taken, the sample of
carbon-14 will be the most active.
(3) The chance that an atom of carbon-14 will decay in the next hour is greater than the chance that
an atom of cobalt-60 will decay in the same time.
A. (1) only *
36.
B. (3) only
C. (1) and (2) only
D. (2) and (3) only
14
C is used for the dating of a wooden archaeological specimen. Three measurements taken are listed
below:
Specimen
1 g sample of living wood
1 g sample of archaeological specimen
no sample
Count-rate
80 counts per minute
40 counts per minute
20 counts per minute
Given that the half-life of 14C is 5700 years, what is the approximate age of the specimen?
A. 4200 years
B. 5700 years
C. 8550 years
D. 9000 years *
P.5
--End of Paper--
Physics Practice Paper 1 (MC) Suggested Answers with explanation
1. Upward journey: 4 = d/t
Downward journey: 6 = d/t’
Whole journey: average speed <v> = 2d/(t+t’) = 2d / (d/4 + d/6) = 4.8 m/s
2. The rope at a higher position has a higher tension (i.e. stretched more) because it has to support more
weight (the weight as well as the weight of the rope below).
5. Since the plane is moving at constant speed, all forces are balanced.
6. s = 50 sin30º  2 –
1
(10)  (2)2 = 30 m
2
7. Faster method: using the following energy method,
Average power = KE gained / time = (1/2) x 2500 x 202 / 5 = 100000 W
8. Area under graph = change in momentum
9.
g = r2
10 = 1 000 2
 = 0.1 rad s–1
0.1
= 0.0159 rev s–1
2
13. Path difference = 5 – 3 = 2 cm = (1/2) 
Required answer =
If the sources are in phase, then destructive interference occurs. However, the sources are operating
exactly out of phase, so the result is constructive interference. So the resulting amplitude is A+A = 2A
19. For (1), PV = nRT, so if P, V and T are the same for both gases, they must have the same no. of moles.
For (2), rms speed of H should be higher than O because they have the same average ke (Same
temperature implies same molecular KE (average KE = 3RT/2NA).
For (3), hydrogen molecules have an average higher speed, so they would make more collisions with
the wall than oxygen molecules.
20. The number of moles before and after is the same.
Before:
n = PV/RT = 140 x 105 x 4 x 10-3 / (RT)
After:
n = N x PV/RT = N x 1.1 x 105 x 4 x 10-3 / RT
where N is the number of balloons.
Equating, we have N = 318.
24. F = qE = qV/d = 5 x 10-6 x (60 / 0.02) = 0.015 N
25. The force between A and B is originally attractive, thus A and B carries unlike charges. Let ball A
carries charge q while B carries charge –q. Charges are distributed evenly after the contact of identical
metal balls. After A and C contact each other, they both carry
other, B carries －
q
charge. After C and B contact each
2
q
charge. Therefore, the force between A and B becomes
4
q q

1 q2 1
F'  k 2 2 4  k 2  F
8 r
8
r
26. Current through R is 1A and current through 2R is 0.5A.
So power P = VI = 3 x (1+1+0.5) = 7.5 W
30. qvB = mv2/r
=>
If B is doubled, r is halved for constant v.
31. For (1), there is no induced current because this is not a closed circuit.
For (2), use Fleming’s right hand rule to find out the direction of current. Regard the rod as the
interior of a cell or battery.
32. Current through the bulb = I = P/V = 24/6 = 4A
Current in cables = 4/20
(because voltage is stepped down, hence current is stepped up)
2
Power loss in cables = P = I r = (4/20)2 (10) = 0.4 W
35. For (1), carbon has the longest half-life, so the decay constant k is smallest. Use the equation A = kN
to solve this problem.
36. 1 g of living wood contributes 60 cpm
1 g of specimen contributes 20 cpm
20 = 60 e – (ln2 / 5700) t
=> t = 9000 years.