2012 dse physics paper 1a

2014-DSE
MOCK
2012-DSE

SET 3

PHY
PAPER1A

HONG KONG EXAMINATIONS AND ASSESSMENT AUTHORITY
HONG KONG 01 PLOMA OF SECONDARY EDUCATION EXAMINATION 2012

PHYSICS PAPER 1
8.30 am - 11.00 am (2% hours)
This paper must be answered in English
GENERAL INSTRUCTIONS
(1)

•

There are TWO sections, A and B, in this Paper. You are advised to finish Section A in about
60 minutes.

(2)

Section A consists of multiple-choice questions in this question paper, while Section B contains conventional questions printed separately in Question-Answer Book B.

(3)

Answers to Section A should be marked on the Multiple-choice Answer Sheet while answers to
Section B should be written in the spaces provided in Question-Answer Book B. The Answer
Sheet for Section A and the Question-Answer Book for Section B will be collected separately at the end of the examination.

(4)

The diagrams in this paper are NOT necessarily drawn to scale.

(5)

The last two pages of this question paper contain a list of data, formulae and relationships which you may find useful.

INSTRUCTIONS FOR SECTION A (MULTIPLE-CHOICE QUESTIONS)
(1)

Read carefully the instructions on the Answer Sheet. After the announcement of the start of the examination, you should first stick a barcode label and insert the information required in the spaces provided. No extra time will be given for sticking on the barcode label after the 'Time is up' announcement. (2)

When told to open this book, you should check that all the questions are there. Look for the words
'END OF SECTION A' after the last question.

(3)

All questions carry equal marks.

(4)

ANSWER ALL QUESTIONS. You are advised to use an HB pencil to mark all the answers on the
Answer Sheet, so that wrong marks can be completely erased with a rubber. You must mark the answers clearly; otherwise you will lose marks if the answers cannot be captured.

(5)

You should mark only ONE answer for each question. If you mark more than one answer, you will receive NO MARKS for that question.

(6)

No marks will be deducted for wrong answers.

1*W!Jt!lHI
Hong Kong Examinations and Assessment Authority
All Rights Reserved 2012
2014-M
2012-DSE-PHY lA-l

1

Not to be taken away before the end of the examination session

Section A
There are 36 questions. Questions marked with
I.

* involve knowledge of the extension component.

Two metal blocks X and Y of the same mass and of initial temperatures 40°C and 30°C respectively are in good thermal contact as shown. The specific heat capacity of X is greater than that of Y. Which statement is correct when a steady state is reached? Assume no heat loss to the surroundings.

BlockX

The temperature of block X is higher than that of block Y.
Their temperature becomes the same and is lower than 35°C.
Their temperature becomes the same and is higher than 35°C.
Their temperature becomes the same and is equal to 35°C.

A.
B.
C.
D.
2.

When a patient's arm is wiped by a piece of cotton soaked with alcohol, the wiped area will feel cool as that patch of alcohol on the skin evaporates. Which statement explains this phenomenon?
A.
B.
C.
D.

*3.

Block Y

The evaporation of alcohol absorbs heat from the patient's arm.
The alcohol on the skin releases latent heat to the surrounding air.
The motion of all the molecules in the patch of alcohol slows down.
Air molecules remove heat from the patch of alcohol by conduction.

An ideal gas is contained in a closed vessel of fixed volume. The graph below shows the variation of pressure p of the gas against its Celsius temperature

e.

p

O'------e
If the number of gas molecules in the vessel is halved, which graph of the dotted line best shows the relationship between p and e?
A.

B.

p

P

,;

o
C.

,;

'"

,.

,;

,;

D.

p

O'------e

"
""
"

P

o
2

,.

e

0

e

""

2012-DSE-PHY lA-2

,;

,;

,;

"

"
""

e

4.

Which ofthe following descriptions is correct?
A.
B.
C.
D.

When water at 25°C is heated to 50°C, both the kinetic energy and potential energy ofthe water molecules increase.
When water at 25°C is heated to 50°C, only the potential energy of the water molecules increases.
When water boils at 100°C and turns into steam, the kinetic energy of the water molecules increases.
When water boils at 100°C and turns into steam, the potential energy of the water molecules increases.

5.

Two forces F J and F z of constant magnitudes act at the same point as shown. When the angle () between FJ and F2 increases from 0° to 180°, the magnitude of the resultant force
A.
B.
C.
D.

6.

decreases throughout. increases throughout. decreases and then increases. increases and then decreases.

A uniform gangplank PQ of a ferry smoothly hinged at end P initially rests horizontally on the pier.
The gangplank has mass M and length 2 m. It is raised by a man on the ferry using a light rope passing a smooth fixed light pulley and connecting to R on the gangplank as shown. R is 1.5 m from end P.
Which of the following correctly describes the force required to raise the gangplank steadily?

initial force required to raise the gangplank when it is horizontal

subsequent force required to raise the gangplank

A.

0.67 Mg

greater than 0.67 Mg

B.

0.67 Mg

smaller than 0.67 Mg

C.

0.94Mg

greater than 0.94 Mg

D.

0.94Mg

smaller than 0.94 Mg

2012-DSE-PHY IA-3

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7.

Which of the following graphs (velocity-time and displacement-time) best represent the motion of a ball falling from rest under gravity at a height H and bouncing back from the ground two times ?
Assume that the collision with the ground is perfectly elastic and neglect air resistance. (Downward measurement is taken to be negative.)

(1)

(2)

velocity

velocity

-l,..--.

o

........

time

(3)

displacement

displacement

(4)

H

time

time

A.
B.
C.
D.

(1) and (3) only
(1) and (4) only
(2) and (3) only
(2) and (4) only

8.

Blocks P and Q of mass m and 2m respectively are connected by a light spring balance and placed on a smooth horizontal surface as shown. If horizontal forces F\ and F2 (with F\ > F 2 ) act on P and Q respectively and the whole system moves to the left with constant acceleration, what is the reading of the spring balance?

A.
B.

c.
D.
9.

3

2(FJ -F2 )
3

2FJ +F2
3

FJ +2F2
3

An object of mass 0.5 kg is raised vertically from the ground by a motor. The object is raised 2.5 m in
1.5 s with uniform speed. Estimate the output power of the motor. Neglect air resistance.
(g= 9.81 m S-2)
A.
B.
C.

5.5W

D.

16.4 W

2012-DSE-PHY lA--4

8.2 W

1l.0W

4

•
•

10.

A block of mass m resting on a 30° incline is given a slight push and slides down the incline with a uniform speed. Which of the following statements about the block's motion on the incline is/are correct? m

(1)
(2)
(3)

There is no net force acting on the block.
The frictional force acting on the block is 0.5 mg.
If the block is given a greater initial speed, it will slide down the incline with acceleration.
A.
B.
C.
D.

(1) only
(3) only
(1) and (2) only
(2) and (3) only

11.

A block of mass m initially resting on a rough horizontal surface is pulled along the surface by a horizontal force F increasing from zero. If the frictional force is constant, which graph shows the relation between the acceleration of the block a and force F?
A.

B.

a

a

O'---L----_F

c.

O'----"""-----F

D. a a

IO...-_ _ _ _ _ _

*12.

F

F

A bomber aircraft is 1 km above the ground and is flying horizontally at a speed of 200 m s-1. The aircraft is going to release a bomb to destroy a target on the ground. How long before flying over the target should the bomb be released? Assume that the bomber aircraft and the target are in the same vertical plane and neglect air resistance. (g = 9.81 m S-2)
A.
B.
C.
D.

2012-DSE-PHY lA-5

5.6 s
10.1 s
14.3 s
It cannot be calculated as the horizontal distance between the aircraft and the target is not known.

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13.

On a smooth horizontal surface, a circular disk P moving at velocity u along the x direction collides obliquely with an identical disk Q initially at rest as shown below. The mass of each disk is m. Which statements about the collision is/are correct?

, ... I

I

&

u

/

I

"

I

I

L

\

,.. i/"-I

P

...,
I

,P

Y

I

'.

-----

x

"-'V"

')