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________________________________________________________________________This Question Paper consists of 16 printed pages (including the cover page).

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Name : _________________________________ Index Number : ________

Class : ______

Clementi Town Secondary School

Preliminary Examination 2009Secondary 5 Normal (Academic)

Science (Physics) 5116/2Paper 2 Duration : 1 h 15 min

CLEMENTI TOWN SECONDARY SCHOOL CLEMENTI TOWN SECONDARY SCHOOL CLEMENTI TOWN SECONDARY SCHOOL CLEMENTI TOWN SECONDARY SCHOOLCLEMENTI TOWN SECONDARY SCHOOL CLEMENTI TOWN SECONDARY SCHOOL CLEMENTI TOWN SECONDARY SCHOOL CLEMENTI TOWN SECONDARY SCHOOLCLEMENTI TOWN SECONDARY SCHOOL CLEMENTI TOWN SECONDARY SCHOOL CLEMENTI TOWN SECONDARY SCHOOL CLEMENTI TOWN SECONDARY SCHOOL

CLEMENTI TOWN SECONDARY SCHOOL CLEMENTI TOWN SECONDARY SCHOOL CLEMENTI TOWN SECONDARY SCHOOL CLEMENTI TOWN SECONDARY SCHOOLCLEMENTI TOWN SECONDARY SCHOOL CLEMENTI TOWN SECONDARY SCHOOL CLEMENTI TOWN SECONDARY SCHOOL CLEMENTI TOWN SECONDARY SCHOOL

Instructions to candidates:

Do not open this booklet until you are told to do so.

Write your name, class and index number in the spaces at the top of this page and on any writingpaper used.

Section AAnswer all the questions. Write your answers in the spaces provided on the question paper.

Section BAnswer any two questions. Write your answers on the writing papers provided on pages 13 to 16.

Information for candidates:

The intended marks for questions or parts of questions are given in brackets [ ].

Take acceleration due to gravity, g, to be 10 m/s2.

For Examiners Use Marks

Section A / 45Section B / 10

/ 10

Total / 65

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Section A (45 marks)Answer all the questions in the spaces provided.

1 An advertisement in the newspaper reads:

At BMW, we see no reason why deceleration cant be made just as exciting asacceleration. In fact, its something we demand of all of our cars. Designed to bite

hard and fast at temperatures of up to 750 C, the brakes on our BMW M3 cantake you from 100 km/h to a complete standstill in just 2.8 seconds.

(a) Convert 100 km/h to m/s. [1]

(b) Calculate the deceleration of the car if it takes 2.8 s to come to rest from aninitial speed of 100 km/h. [2]

(c) Calculate the minimum distance the car needs in front of it to come to a stop if itis initially travelling at 100 km/h. [1]

(d) Assuming that the car has a mass of 1500 kg, calculate the magnitude of theforce produced by the brakes in stopping the car. [2]

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(d) The advertisement mentions that the brakes can operate up to 750 C. Suggestwhy it is important for brakes to be able to withstand high temperatures? [1]

2 A weight W is suspended by two ropes as shown in Fig. 2.1. The tensions in both theropes are 60 N. By means of a scale diagram, find the resultant of the two tensionsand hence find the weight W. [5]

Fig. 2.1

35 35

W

60 N60 N

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3 Fig. 3.1 shows a uniform rod XY of length 1.20 m and weight 10.0 N freely hinged toa wall at X. It is held horizontally by two forces P and Q, both acting at Y. The twoforces are perpendicular to each other.

(a) Calculate the moment of the weight of the rod about X. [2]

(b) If the magnitude of the force Q is 6.0 N, what is its moment about the hinge at X.[1]

(c) Determine the value of P.[2]

Fig. 3.1

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4 Fig. 4.1 shows several positions of a pendulum as it swings back and forth.

Fig. 4.1

(a) Based on Fig. 4.1, describe what is meant by the terms oscillation and periodof a pendulum. [2]

(b) Given that the time taken to move from X to Z is 0.25 s, what is the period of thependulum? [1]

(c) Calculate the frequency of oscillation of the pendulum. [1]

(d) State what is meant by the Principle of Conservation of Energy. [1]

(e) Assuming the point X is 20 cm higher than the point Y and the mass of the bobis 0.4 kg, calculate the difference in gravitational potential energy betweenpoints X and Y. [2]

X

Y

Z20 cm

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5 Fig. 5.1 shows the path of the light ray through a rectangular glass block and into theair again.

Fig. 5.1

(a) Using the information given in the diagram, determine the refractive index of the

glass block. [2]

(b) State the angles x and y. [1]

x = ________________; y = ________________.

(c) Given that the speed of light in air is 3.0 x 108 m/s, what is the speed of light inglass? [2]

6 Messages travelling from the NASA Pathfinder Probe on Mars to the Earth takeapproximately 1 minute to travel from Mars to the Earth. These messages aretransmitted using radiowaves, and are picked up by NASAs network of antennae onthe Earth.

(a) Suggest why sound waves are not used to transmit messages to outer space. [1]

36

25

x

y

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(b) Calculate the approximate distance of Mars from the Earth. [2]

(c) The mass of the probe was measured at 120 kg on the Earth. If the weight ofthe probe was calculated at 400 N on Mars, what is the acceleration due togravity on Mars? [2]

7 Fig. 7.1 shows some water being heated by a 50 W immersion heater.

The temperature of the water was taken at regular intervals. Fig. 7.2 shows the graph

that was drawn from the results.

(a) Describe how the speed and separation of the water molecules changes

(i) between A and B, and [1]

(ii) between B and C. [1]

Fig. 7.1

water

50 W immersion heater

to power supply

thermometer

Fig. 7.2

temperature/C

time/minutes

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(b) (i) Between B and C, the mass of water in the beaker decreases by 10 g.Calculate how much energy is needed to boil 10 g of water at 100 C [2]

(ii) The actual amount of heat energy needed to change 10 g of water at100 C to steam is 22 600 J. Suggest a reason wh y the value calculated in(b)(i) is different. [1]

(c) In both boiling and in evaporation, a liquid changes into a gas. State twodifferences between boiling and evaporation. [2]

8 A block of mass 1.62 kg is to be placed on a table. The dimensions of the block isshown in Fig. 8.1.

Fig. 8.1

(a) Which surface A, B or C, when placed on the table, will give the maximumpressure? Explain your choice. [2]

(b) Calculate this maximum pressure that the block could exert on the table. [2]

A

B

C

3 cm

12 cm15 cm

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Section B (20 marks)

Answer any two questions from this sectionWrite your answers on pages 13 to 16 and, if necessary,

continue on separate answer paper.

9 (a) Fig. 9.1 shows a battery of e.m.f. 12 V connected to three resistors.

Fig. 9.1

(i) Calculate the effective resistance of the two resistors connected inparallel. [2]

(ii) Calculate the current flowing in the ammeter. [2]

(iii) Find the potential difference between the points A and B. [1]

(b) An electric kettle, operating from a 240 V mains supply, uses electrical energy ata rate of 1.92 kW.

(i) Calculate the current that flows through the heating element of thekettle. [2]

(ii) What is the resistance of the heating element in the kettle? [1]

(iii) If 1 kWh of electrical energy costs 30 cents, calculate the cost of runningthe kettle for 45 min each day. [2]

20

60

60

A B

12 V

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10 (a) In Fig. 10.1 below, an object, O is placed in front of a convex lens. The objectdistance and focal length are shown full scale on the figure.

Fig. 10.1

(i) Draw construction rays on Fig. 10.1 to locate the position of image. [2]

(ii) State the image distance you obtained from your diagram. [1]

(iii) State two characteristics of the image obtained. [2]

(iv) Suggest one application for the setup shown in Fig. 10.1. [1]

(b) Fig. 10.2 shows a girl standing 150 m in front of a building. She fires a shotwith a starting pistol. A boy, standing 350 m behind her, hears two bangs, which

are 1 s apart.

Fig. 10.2

(i) Calculate the speed of sound in air using the information provided. [2]

(ii) What type of wave is sound wave? [1]

(iii) Give your reason why sound is categorized as this type of wave. [1]

convex lens

F FO

150 m 350 m

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11 (a) Fig.11.1 shows a light aluminium rod resting between the poles of a magnet. Acurrent is passed through the rod from two brass strips connected to a powersupply.

Fig. 11.1

(i) On Fig. 11.1, draw the direction of the current in the rod when the switch isclosed. [1]

(ii) State which way the rod moves when the switch is closed. [1]

(iii) State the effect on the movement of the rod when

1. the current is increased, and [1]

2. the current is reversed. [1]

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(b) Four magnetic specimens were tested using the apparatus shown in Fig. 11.2.The results, which show how many nails were attracted to the specimen whenthe switch was on, and how many were still attracted when the switch was off;are shown in the table below.

Fig. 11.2

specimen number attractedwhen switch was on

number still attractedwhen switch was off

A 20 8B 20 18C 35 3D 35 32

(i) Which would make the best electromagnet? Explain your answer. [2]

(ii) Suggest a suitable material for the specimen which makes the bestelectromagnet. [1]

(c) Fig. 11.3 shows a part of a device called a gold leaf electroscope. The plate, rodand leaf are all made of metal. Fig. 11.4 shows what happens to the gold leaf

when a positively charged strip is held close to the plate.

Fig. 11.3 Fig. 11.4

Explain why the leaf moves away from the rod when the positively charged stripis held near the plate. [3]

END OF PAPER

specimenunder

test

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Answers to Prelim Examination 2009 Sec 5N Science (Physics) Paper 2

1 (a) Initial speed = 100 km/h= 100/3.6= 27.8 m/s [1]

(b) a = (v u)/t

= (0 27.8)/2.8= - 9.93 m/s2 [1]ECF

deceleration = 9.9 m/2 [1]

(c) Distance = 0.5 2.8 27.8 [1]= 38.9 m [1]

(d) F = m a= 1500 9.9 [1]ECF= 14850 N [1]

(e) A large amount of heat is produced in the brakes as a result of friction when thecar decelerates. [1]

2 Scale 1 cm : 10 N [1]

Hence W = 68.8 N downwards. [1] ECF

3. (a) Moment of weight about X = 10.0 x 0.60 [1]= 6.0 Nm [1]

(b) 0 Nm [1]

(c) Taking moments about X,

P x 1.20 = 6.0 [1]P = 5.0 N [1]

70

60 N

60 N

Ans: 68.8 N [1] upwards

(accept 66 72 N)

correct diagram [1]correct resultant in upwarddirection [1]

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4. (a) One oscillation is a complete to-and-fro motion of the pendulum i.e. if thependulum is released from point X, one oscillation is the motion of the pendulumfrom point X to point Z and back to point X [1]. The period is the time taken forthe pendulum to travel from point X to point Z and back to point X [1].

(b) T = 0.25 2= 0.50 s [1]

(c) f = 1/T= 1/0.50= 2 Hz [1] ECF

(d) The Principle of Conservation of Energy states that the total amount of energy isa given system is constant (same). Energy cannot be created or destroyed, butonly change from one form to another. [1]

(e) PE = mgh= 0.4 10 0.20 [1]

= 0.8 J [1]

5. (a) n = sin i / sin r= sin 36 / sin 25 [1]= 1.39 or 1.4 [1]

(b) x = 25 y = 36 [1]

(c) n = (speed of light in vacuum) / (speed of light in the glass)1.4 = 3.0 108 / speed of light in the glass [1]speed of light in the glass = 2.1 108 m/s [1]

6. (a) Sound waves cannot propagate (or travel) in space (or vacuum) [1]

(b) Distance = speed time= 3.0 108 1 60= 1.8 1010 m

(c) W = m g400 = 120 g [1]g = 3.3 m/s2 [1]

7. (a) (i) the speed increases [1/2] and the molecules move further apart [1/2](ii) the speed is constant[1/2] separation increases greatly [1/2]

(b) (i) Energy = power x time= 50 x 10 x 60 [1]= 30000 J [1]

(ii) Heat is lost to the surroundings/atmosphere. [1]

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(c) - Boiling occurs at a fixed temperature but evaporation occurs at anytemperature.

- Boiling occurs in the body of the liquid but evaporation occurs at thesurface.

- The rate of evaporation depends on temperature/wind/surfacearea/humidity but boiling is not affected by these.

[Any two for 2 marks]

8 (a) C. [1] C has the smallest area and pressure is greatest with thesmallest area. [1]

(b) Calculate this maximum pressure that the block could exert on the table. [2]

P =F

A

=162. x 10

12 x 3[1]

= 0.45 N/cm2 [1] or 4500 N/m2

9 (a) (i) R = (1/20 + 1/60)-1 [1]= 15 [1]

(ii) I = V/R= 12/(15+60) [1]= 0.16 A[1]

(iii) V = IR= 0.16 x 15= 2.4 V[1]

(b) (i) P = VI

I =240

1920=

V

P[1]

= 8 A [1]

(ii) P =R

V2

R = ==1920

240

P

V 2230 [1]

Or R = V/I= 240/8= 30 [1]

(iii) Cost of electricity = 45/60 1.92 0.30 [1]= $0.432 [1]

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10 (a) (i)

(ii) 3.5 cm 0.2 cm [1](iii) real, inverted ( or diminished ) [1 mark each](iv) A camera or in the eye [1]

(b) (i)v

t350

1=

vt

6502=

smv

v

vv

tt

/300

1300

1350650

112

=

=

=

=

[1]

(ii) Longitudinal wave. [1]

(iii) The direction of the particles vibration is parallel to the direction of thewave motion. [1]

[1]

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11 (a) (i)

Direction of current indicated from right to left. [1]

(ii) Out of the page or away from magnet. [1]

(iii) 1. The rod moves faster in the same direction. [1]2. The rod moves in the opposite direction (into the page). [1]

(b) (i) Specimen C [1]. It is a material that magnetises and demagnetises the

easiest [1].

(i) Soft Iron. [1]

(c) The electrons from the lower part moves to the plate as they are attracted tothe positively charged strip. [1]This causes both the leaf and lower part of the rod to be positivelycharged, [1]So the leaf is repelled from the rod. [1]