Index Number

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Index Number

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BEDOK SOUTH SECONDARY SCHOOL PRELIMINARY EXAMINATION 2009 SECONDARY 4 Express

Subject: PHYSICS Paper 1

Duration: 1 hr

Date: 13 Aug 2009 (Thursday) READ THESE INSTRUCTIONS FIRST Write in soft pencil. Do not use paper clips, highlighters, glue or correction fluid. Write your name, class and index number on the answer sheet in the spaces provided.

There are forty questions in this paper. Answer all questions. For each question there are four possible answers A, B, C and D. Choose the one you consider to be correct and record your choice in soft pencil on the separate answer sheet. Read the instruction on the Answer Sheet very carefully. Each correct answer will score one mark. A mark will not be deducted for a wrong answer. Any rough working should be done in this booklet.

This document consists of 18 printed pages. [Turn Over

2 1

2

Which row does not correctly indicate the object’s order of magnitude? objects

order of magnitude

A

diameter of an atom

0.1 nm

B

length of MRT train

300 m

C

height of Mount Everest

9.0 km

D

radius of earth

6.0 Mm

The Singapore flag is displayed across the sky by a cable pulled using an Apache helicopter. Three forces are acting on the state flag. The weight (W) due to gravity, the drag due to the air resistance (R) and the tension in the cable (T).

Which of the following shows the resultant of any of the two forces? A

B

W

T

W

R

C

D R

W

T

R

3 3

A student is trying to find the density of a stone, but he has mixed up the instruction cards.

What order should the cards be in?

4

A

5→3→6→2→1→4→7

B

5→6→4→2→1→7→4

C

1→5→3→6→2→7→4

D

1→4→5→3→6→2→7

An astronaut of mass 80 kg jumped out of the rocket after it had landed on Jupiter. The astronaut took 0.40 s to drop for 2.0 m. What was the weight of the astronaut on Jupiter? A 800 N

5

B 1000 N

C 1800 N

D 2000 N

A bottle full of water has a mass of 200 g. When the same bottle is filled with liquid X, the mass becomes 180 g. (Take density of water = 1 g/cm3) Given that the mass of the empty bottle is 100g, what is the density of the liquid? A 0.2 g/cm3

B 0.8 g/cm3

C 0.9 g/cm3

D 1.2 g/cm3

[Turn Over

4 6

A shuttlecock is balanced at the corner of a wall. Force R is the normal reaction force of the wall on the shuttlecock while W is the weight of the shuttlecock. You may take point P to be the pivot.

R

3.5cm P W

8.0cm

7.0cm Given that the mass of the shuttlecock is 5 g, what is the reaction force R? A 0.001 N 7

B 0.0143 N

C 0.0200 N

D 1.43 N

Peter is a polytechnic student. He has recently decided to work on a project to design and construct a lamp. Before he carried on with the construction, he decided to do some research on previously manufactured lamps. One of the lamps that he found is as shown. This lamp looks pleasing except that it has a high tendency to fall when a strong gust of wind blows.

Which of the following reason cannot be a possible reason to explain its poor stability? A The lamp’s centre of gravity is located very high up due to the mass distribution. B When tilted to one side, the centre of gravity falls within the base area. C It will continue to fall further due to the moment produced, away from its original position when slightly displaced. D Since the base area is small, its line of action of the weight easily acts outside this area.

5 8 What is not true of two forces that give rise to a couple? A They act in opposite directions. B They both act at the same point. C They both act on the same body. D They both have the same magnitude.

9 A U-tube is filled with oil and water as shown below. The density of the oil is 800 kg/m3 and that of water is 1000 kg/m3.

What is the height h? A 10 cm

B 12 cm

C 16 cm

D

24 cm

10 The diagram shows a hydraulic pump.

Which of the following statements about the hydraulic pump is not true? A The pressure applied to an enclosed fluid is transmitted to all parts of the liquid. B The liquid must be incompressible. C A small effort F is needed on a piston P to lift load at piston Q. D When lifting the load, effort F will move through a smaller distance than load.

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6 11 An electric motor runs on 230 V a.c. supply with a current of 3 A. It lifts a load of 200 N through a distance of 6 m in 2 s.

What is efficiency of this motor? A 13 %

B 78%

C 87 %

D 100 %

12 When a gas of fixed mass is heated under constant pressure, 1 2 3

the volume of the gas increases. the average speed of the gas molecules increases. the average separation of the gas molecules increases.

Which of the following statement(s) is/are true? A 1 only

B 2 only

C 2 and 3 only

D 1, 2 and 3

13 In a Brownian motion experiment involving smoke particles in the air, heavy particles settle quickly but very small particles remain suspended for long periods of time. This is because A

air pressure has a greater effect on smaller particles.

B

random molecular bombardment by air molecules keeps the particles suspended.

C

the Earth’s gravitational field does not act on very small particles.

D

the small smoke particles have the same density as air.

7 14 The following figures show an old method of keeping food warm. The hot pot is surrounded with dry hay. The hay for container Q is more loosely packed compared to the hay for container P.

Which of the following statement is true? A Metal pot in P will retain heat longer than Q as there is more hay in P. B Metal pot in P will retain heat longer than Q as the more compact hay will prevent heat loss by convection. C Metal pot in Q will lose heat at a slower rate than that in P as there is more trapped air in Q. D Both metal pots in P and Q will lose heat at the same rate as they are housed within the same type of wooden container. 15 The diagram shows two blocks of aluminium, R and S. The mass of R is half the mass of S. The temperature rise of S is half the temperature rise of R when the same amount of heat, W, is supplied to each block.

R

S

W

W

Which of the statement correctly explains the observation? A The heat capacity of R is half the heat capacity of S. B The heat capacity of R is twice the heat capacity of S. C The specific heat capacity of R is half the specific heat capacity of S. D The specific heat capacity of R is twice the specific heat capacity of S. [Turn Over

8 16 The graphs below represent the variations in the displacement of a sinusoidal wave with distance and time.

Which of the following correctly describes the wavelength, amplitude, frequency and speed of the wave? wavelength 1m 2m 2m 2m

A B C D

amplitude - 0.5 m 0.5 m 0.5 m 1.0 m

frequency 4 Hz 2 Hz 0.25 Hz 0.25 Hz

speed 4 m/s 4 m/s 0.5 m/s 0.5 m/s

17 The diagram shows the waves in a ripple tank in which the water in parts P and Q is of different depths.

P

Q

Which of the following correctly describes how the depth of the water as well as the frequency and speed of the waves change when the waves pass from P to Q? depth of water frequency speed A

deeper

decreases

increases

B

shallower

increases

decreases

C

deeper

no change

increases

D

shallower

no change

decreases

9 18 Three students stand 1 m apart in front of a plane mirror that is 1 m long. 1m Mirror

1m Student X

1m Student Y

Student Z

Student X stands in line with one edge. How many students can see the images of the other two? A

0

B

1

C

2

D

3

19 A swimming pool is lit by a lamp at the bottom of the pool. The incident ray and the angles it makes are as shown. r 60°°

48.3°°

q p water

Which of the following set of angles could not possibly occur as the incident angle varies? p q r A 30.1 30.1° 22° B 36.9° 36.9° 53° C 48.8° 90° 90° D 65.5° 65.5° 20 Which of the following is not true about the effect of absorbing electromagnetic radiation? A

Absorbing infrared radiation makes us feel warm.

B

Exposing developing foetus to ultraviolet radiation can lead to deformed baby.

C

Ionising radiation due to gamma rays can cause damage to chromosomes which bears DNA.

D

Excessive exposure of ionisation radiation may lead to premature aging and blood cancer.

[Turn Over

10 21 Figure A shows the original positions of the air particles in equilibrium. A sound wave is transmitted and the particles are disturbed as shown in Fig. B.

Fig. A

Fig. B Which of the following graphs is a correct displacement–distance graph for the air partilces as shown in Figure B? Take the direction to the right as positive. A

B

C

D

11 22 M, N, O and P are pith balls which behave as follows:M repels N; M attracts O and O repels P. If P is positively charged, A

N must be positively charged.

B

N must be negatively charged.

C

N must be positively charged or neutral.

D

N must be negatively charged or neutral.

23 How much charge flows through an electric bulb when a current of 0.5 A flows for half an hour? A

0.25 C

B

0.5 C

C

180 C

D

900 C

24 Electromotive force is defined as A the work done by an appliance in driving electrons round a complete circuit. B the work done by a source in driving a unit charge round a complete circuit. C the work done in driving a unit charge through an electrical component D product of current and resistance.

25 A 8 m long wire with a diameter of 3 mm has a resistance of 16 Ω. What is the resistance of the same type of wire which is 2 m long and has a diameter of 2 mm? A

2.7 Ω

B

3.6 Ω

C

6.0 Ω

D

9.0 Ω

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12 26 Four diodes are used to rectify an alternating voltage V. X V

Which of the following graphs is a correct rectification formed for the fixed resistor if diode X stops functioning? V

V

A

B

t

t

C

V

D

V

t

t

27 An unknown resistor is connected in a circuit as shown. 9V

6Ω R 1A

3Ω

What is the resistance of R? A

1Ω

B

2Ω

C

4Ω

D

9Ω

13

28 Which of the following graphs best describe how the electric potential varies along 1- 6 in the circuit below?

2Ω 1

5Ω 2 3

A

V

1

2

3

4 5

6 B

V

4

5

1

6

C

2

3

4

5

6

3

4

5 6

D V

V

1

2

3

4

5

6

1

2

29 The circuit shown is used to detect the level of sunlight. The resistance of the LDR is 1 MΩ in the dark and 100 Ω in bright sunlight.

What is the ratio of potential difference between the fixed resistor and LDR in the dark? A

1:100

B

1: 10 000

C 100: 1

D 10 000 : 1

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14 30 The figure below shows the graphs for the I-V characteristics of three different components P, Q and R. I

I P

I Q

V

R

V

V

Which of the following correctly describes the components P, Q and R?

A

P semiconductor diode

Q filament lamp

R metallic conductor

B

filament lamp

metallic conductor

semiconductor diode

C

filament lamp

semiconductor diode

metallic conductor

D

metallic conductor

semiconductor diode

filament lamp

31 A 3-pin mains plug is fitted to the lead for a 1000 W electric kettle to be used on a 240 V a.c. supply. Electricity costs 15 ¢ per unit. Which of the following statements is not correct? A

A 5 A fuse is the most appropriate value to use.

B

The yellow and green wire should be connected to the live pin.

C

A total cost of $9 will be charged for usage of 2 hours per day for 30 days.

D

The blue wire is connected to the zero potential.

32 Two bulbs X and Y have the power ratings shown. X

230 V, 100 W

Y

230 V, 60 W

When operating normally, which has the larger current and which has the larger resistance?

A B C D

larger current X X Y Y

larger resistance X Y X Y

15 33 An insulated wire is wound round an iron rod. Near the rod is a small magnet. S

N

magnet When the switch is closed, which of the following does NOT occur? A Current flows through the iron rod. B A magnet field is formed. C The small magnet is attracted to the solenoid. D Heat is generated in the coil.

34 Which of the following is an example of induced magnetism? A A steel bar in a solenoid that carries a current is magnetised. B The soft iron core of an electromagnet is magnetised when current is switched on. C The needle of a plotting compass is pointing to the S-pole of a magnet. D An iron nail attached to a bar magnet is able to attract another iron nail.

35 To demagnetise a steel bar magnet, the electrical method is employed. Below are steps. 1 2 3 4 5

Insert the magnetised steel bar into a solenoid. Connect direct current to a solenoid. Connect alternating current to a solenoid. Pull the steel bar slowly out of the solenoid. Switch off the current supply

What is the correct sequence? A

1→2→ 4→5

B

3→1→4→5

C

2→1→4→5

D

1→3→5→4

[Turn Over

16 36 The diagram shows three parallel wires X, Y and Z spaced d distance apart. Each carries current of equal magnitude in the directions shown. X Y Z

I

I d

I d

The resultant force experienced by Y due to the currents in X and Z is

37

A

perpendicular to the plane of the paper.

B

to the left.

C

to the right.

D

zero.

An electron beam is about to enter a strong magnetic field in the rectangular region A as shown in the diagram below. A

X

X

X

X

X

X

X

X

X

X

X

X

The electron beam will A continue to move without changing its direction. B deflect out of the paper. C deflect upwards. D deflect downwards.

_

17 38

The diagram below shows a simple d.c. motor.

How can the direction of rotation of the coil be reversed?

A 39

Direction of Magnetic Field

Direction of current

1

maintain

reverse

2

reverse

maintain

3

reverse

reverse

1 only

B

2 only

C

3 only

D

1 and 2 only

Why are high voltages and low currents used to transmit electrical energy over long distances? A to increase the electromagnetic radiation. B to increase the speed at which electrons move. C to reduce heat loss from the power line. D to reduce the resistance of the power line.

18 40

The display represents an alternating voltage from a CRO.

.

From the display on the CRO with the setting shown, the peak current is A 40 A

B 4 mA

C 8 mA

D 16 mA

19 Marking scheme Paper 1 1 2 3 4 5 6 7 8 9 10

B C C D B B B B A D

11 12 13 14 15 16 17 18 19 20

C D B C A C C B A B

21 22 23 24 25 26 27 28 29 30

A B D B D B D B A D

31 32 33 34 35 36 37 38 39 40

B A A D B B C D C C