3e phy my 2010

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Section A (20 marks)

Answer all questions. Each question has four possible answers, A, B, C and D. Choose the

one you consider most appropriate and record your choice in soft pencil on the OTAS

answer sheet.

1 The diagram shows apparatus used to investigate the sound from an electric bell as

air is removed from the container.

What happens to the sound from the electric bell heard from outside?

A It becomes louder.

B It becomes quieter.

C It becomes quieter, then louder.D It remains the same.

2 An electronic synthesizer produces pure notes X and Y as shown in the diagram.

Which of the following is true about the notes X and Y?

A Note X has higher speed than note Y.

B Note X has higher quality than note Y.

C Note X has higher frequency than note Y.

D Note X has higher amplitude than note Y.

3Exp/Phy/5058/MYE/2010 [Turn over

2

Electric power supply

Electric bell

Container

To vacuum pump

X Y

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3 The displacement-time graph of a wave travelling across water at a particular point

with a velocity of 2 cm s-1 is shown in the diagram.

0.1 0.30.2 time/s

2

-2

displacement/mm

00.4 0.60.5

-1

1

What is the wavelength of the wave?

A 0.004 cm B 0.2 cm C 0.4 cm D 10 cm

4 The diagram shows a transverse wave travelling from the left to right.

Which of the following correctly describes the movement of particles at X, Y and Z inthe wave at this particular instant?

X Y Z

A moving upwards moving upwards moving upwards

B moving upwards moving downwards moving upwards

C moving upwards moving downwards momentarily at rest

D moving downwards moving upwards moving upwards


3

YX

Z

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5 The diagram shows waves in a ripple tank passing from deep water to shallow water.

What happens to the speed and frequency of the waves?

Speed Frequency

A decreases decreases

B decreases unchangedC increases unchanged

D unchanged increases

6 Which of the following statement is true?

A The image distance obtained from a distant object is the focal length of the

convex lens.

B The image obtained from a convex lens is always inverted.

C The image obtained from a convex lens always lies on the focal point.D The image obtained from a convex lens is always real.

7 An observer looks straight through a rectangular glass block at an object P, as shown

below. How does the object appear to the observer?

A Diminished B In its actual position

C Moved to the right D Nearer

8 The image of an object formed is smaller than the object when the object is placed 41

cm from a converging lens. When placed at a distance of 39 cm, the image of the

object becomes bigger than the object. What is a possible focal length of the lens?

A 10 cm B 15 cm C 20 cm D 30 cm


4

O

eye

Shallow water Deep water

Wavefront

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9 A ray of light passes through a spherical air bubble in water as shown. Which of the

following represents the path of the emergent ray?

10 The diagram shows an experiment to measure the focal length of a lens.

Which distance is the focal length of the lens?

A x B 2y C y – x D 2(y – x )

11 A motorist travels 200 km. After travelling along a fast road for 2 hours, the motoristuses a slow road for the remaining ½ hour of the journey.

What is the average speed of the car?

A 80 km h-1 B 100 km h-1 C 400 km h-1 D 500 km h-1


5

Plane mirror

Convex lens

y

x

o

A

B

C

D

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12 The distance-time graphs of two cars X and Y are shown below.

Which of the following statements is true?

A Both cars reached their destination at the same time.

B Both cars travelled at the same acceleration

C Both cars travelled at the same speed.

D Both cars travelled the same distance at time t.

13 The graph shows how the distance of an object changes with time. Which section of

the graph shows the object moving with increasing speed?

A OP B PQ C QR D RS

14 A stone is thrown into the air. Which of the following describes its velocity andacceleration due to free fall at its maximum height?

Velocity Acceleration

A decreases decreases

B decreases zero

C increases constant

D zero constant


Car X Car Y

distance

time

t

6

O

distance

time

P

Q

R S

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15 The graph shows how the speed of an object changes with time. Which section of thegraph shows the object moving with decreasing acceleration?

16 The graph below shows the speed-time graph of a car.

What is the acceleration of the car when time is 30 s?

A 0 ms-2 B [(25-5) ÷ 30] m s-2

C 25 m s-2 D (25 ÷ 30) m s-2

17 A force of 3.0 N and a force of 4.0 N act on an object at the same time. Which of the

following forces cannot be the resultant force acting on the object?

A 1 N B 5 N C 7 N D 12 N


7

0 10 20 30 40 50

5

15

25

time/s

speed/m/s

10

20

Speed/ m s-1

Time/ s

Speed

time

A

B

C

D

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18 The wheel of a moving car is driven by the engine. The car is accelerating in the

direction shown. In which direction does the frictional force act on the wheel?

19 A piece of rock, mass 8 kg, is dropped into the sea. If it sinks with a constant speedof 5 ms-1, what is the resultant force exerted on the rock as it sinks?

A 0 N B 80 N downwardsC 80 N upwards D 400 N downwards

20 The diagram shows three boxes P, Q and R resting on the floor. The weight of each

box is indicated.

200 N

50 N

100 N A

B

C

What is the resultant force acting on the box Q?

A 150 N B 100 N C 50 N D 0 N


8

direction of acceleration of car

wheel

road surfaceDB

C

A

P

Q

R

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Section B (50 marks)

Answer all questions on the spaces provided.

1 Fig. 1 shows a ray of light travelling from water and into air.

Fig. 1

If the refractive index of water is 1.3, find the angle of refraction of the light ray

at the water-air interface.

Angle of refraction = ……………………….…….[2]


9

30 °

air

water

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2 A gun is fired at point X between two vertical cliffs as shown in Fig. 2. The first echo

heard at X occurs 2.2 s after firing and the second echo heard after a further 1.3 s.

(a) Calculate the distance between the two cliffs, showing clearly how you arrived

at your result. Take the speed of sound waves in air as 340 m s-1.

Fig. 2

Distance = ……………………….…….[2]

(b) If the wavelength of the sound wave is 10 cm, calculate the frequency of the

wave.

Frequency = ……………………….…….[2]


10

cliff cliff X

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3 In the Fig. 3 below, LMN represents a person standing in front of a vertical mirror

OP. L represents the top of the person’s head, M the eyes and N the feet. The height

of the person is 170 cm and the eyes are 15 cm below the top of the head.

Fig. 3

(a) Show on your diagram, with labelled angles, the path taken by a ray of light

which travels from the

(i) top of the person’s head, reflected by the mirror and enters the eyes,

[1]

(ii) person’s feet, reflected by the mirror and enters the eyes. [1]

(b) (i) Calculate the minimum length of the mirror for the person to be able to

see a full-length image of himself.

Minimum length = ……………………….…….[2]

(ii) Find the distance between the bottom of this mirror and the floor.

Distance = ……………………….…….[1]


11

L

M

N

O

P

.

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4 Fig. 4 shows the apparatus used to demonstrate how a coin and a piece of paper fall

from rest under gravity.

Fig. 4

(a) Explain, in terms of the forces involved, why

(i) the paper falls with constant speed,

...…………….…………………………………………………………………

...…………….…………………………………………………………………

..…………………………………………………………………………….[2]

(ii) the coin accelerates.

...…………….…………………………………………………………………

...…………….…………………………………………………………………

..…………………………………………………………………………….[2]

(b) A vacuum pump is connected to A and the air in the tube is removed. Boththe coin and paper reach the ground at the same time. Explain why this is so.

………………………………………………………………………………………….

………………………………………………………………………………………….

………………………………………………………………………………………….

……………………………………………………………………………………….[2]


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5 Fig. 5 shows a block of weight 50 N hung by two separate strings from a flat wooden

plank.

Determine, by drawing a scaled diagram, the tension in string A. [3]

Fig. 5 (not drawn to scale)


13

30 °

50 N

Weight

30 °

String BString A

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6 A ball is thrown vertically upwards from the ground with a velocity of 20 m s -1.

Assume there is negligible air resistance and acceleration due to free fall is 10 m s-2.

(a) Calculate the maximum height reached,

Height = ……………………….…….[2]

(b) Draw, on Fig. 6 below, the speed-time graph of the ball from t = 0 to t = 4 s.[2]

Fig. 6


14

Speed/ m s-1

time/ s

20

0 1 2 3 4 5

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7 A car of length 3.0 m, starts from rest and accelerates along a straight and level road

as shown in Fig. 7 below.

Fig. 7

The car takes 2.0 s to pass point X. The car travels with a constant acceleration of

2.5 m s-2 and 12.0 s later, the car passed point Y.

(a) Calculate the average speed of the car as it passes through X.

Average speed = ……………………….…….[1]

(b) Calculate the distance travelled from X to Y.

Distance travelled = ……………………….…….[2]


YX

15

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8 A truck is travelling at a constant speed of 25 m s-1. At time t = 0 s, the truck passes a

lamp-post by the side of the road. At the same time, a police car parked besides the

lamp-post accelerates constantly for 15 s to reach a speed of 30 m s -1. After that, the

police car continues to travel at this constant speed of 30 m s-1.

(a) Calculate acceleration of the police car.

Acceleration = ……………………….…….[2]

(b) Sketch the speed-time graphs for both vehicles on the same labelled axes for

t between 0 and 45 s. [2]

(c) Determine if the police car has overtaken the truck at t = 45 s. Show your

workings and explanations clearly.

………………………………………………………………………………………….

………………………………………………………………………………………….

………………………………………………………………………………………….

……………………………………………………………………………………….[3]


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9 Fig. 9 is a full-scale diagram that represents the positions of particles in a medium at

a particular instant when a longitudinal wave, travelling from left to right, passes

through the medium. The positions of the particles are shown as dots on the diagram

when the longitudinal wave passes through.

At the instant shown, the particles X, Y and Z are passing through their originalundisturbed positions. Before the wave arrived, the particles were all 1.0 cm apart

and the original positions of the particles are shown in the diagram as dotted lines.

Fig. 9

(a) By making measurements on the diagram, write down

(i) the wavelength of the wave,

Wavelength = ……………………….…….[1]

(ii) the amplitude of the wave.

Amplitude = ……………………….…….[2]

(b) Mark on the diagram

(i) the centre of compression as C, [1]

(ii) the centre of rarefaction as R. [1]

(c) For the instant shown on Fig. 9, sketch on the axes provided below the

displacement-distance graph of all the particles. On the axes, label the

amplitude of the wave. [3]


17

YX Z

0 1 2 3 4 5 6 7 8 9 10 11 12Distance/ cm

Displacement / cm

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10 A student holds a lens at a distance x away from a piece of paper with the words

“GCE ‘O’ LEVEL PHYSICS” printed on it. The image of what he sees is shown in

Fig. 10. The focal length of the lens is 8 mm.

Fig. 10

(a) (i) Draw a ray diagram on the graph paper, using a scale of 1 cm to

represent 1 mm, to show how the image is formed. [3]

(b) (ii) Determine, by measurement, the value of distance x .

distance x = ……………………….…….[2]

(b) (i) The student wants to increase the size of the image.State whether he should move the lens nearer or further away from

the words.

…………………………………………………………………………………

………………………………………………………………………………[1]


18

GCE ‘O’ LEVEL PHYSICS 3mm 7mm

Lens

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(c )(ii) Explain your answer in (b)(i) by using one or more sketches of ray

diagrams.

…………………………………………………………………………………

…………………………………………………………………………………

…………………………………………………………………………………

…………………………………………………………………………………

………………………………………………………………………………[2]


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Section C (20 marks)

Answer all questions on the writing papers provided.

11 A car is moving along a horizontal road as shown in Fig. 11.1.

Fig. 11.1

The car has a mass of 1000 kg. At time t = 20 s, the combined resistive forces of air

and friction is 500 N. The acceleration of the car is 1.5 m s-2.

(a) Calculate the forward driving force required to accelerate the car. [2]

(b) The car starts from rest and reaches its maximum speed in 30 s. Given that

the average acceleration is 1.5 m s-2, calculate its maximum speed. [2]

(c) With the engine working at full power, the car’s acceleration decreases as it

goes faster. Explain why this is so. [2]

(d) The car travels at its maximum speed for one minute before it starts to slow

down.

(i) Calculate the forward driving force of the car when it is at its maximum

speed if the combined resistive forces of air and friction is ten times as

much as that at t = 20 s. [1]

(ii) Fig. 11.2 shows the speed of the car as it slows down. Interpret the

motion of the car from the graph. [2]

Fig. 11.2

(iii) Explain, in terms of braking distance, why the braking motion seen in

Fig. 11.2 is better than decelerating uniformly if the time taken and the

initial speed is the same for both cases. [1]


20

Forward driving force

Air resistance

Friction

speed

time

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12 Read the article below and answer the questions.

Undersea cable systems transport telephone conversations

Telephone conversations are carried across the oceans of the world as brief pulses

of light in cables that contain hair-thin fibre optic strands. These strands are madefrom glass covered by a cladding that is protected by an outer casing, as shown inFig. 12. If the speed of light in the cladding is greater than in the core, total internalreflection occurs and all light is then confined to the core.

Fig. 12

The transmission of light is not 100% efficient as it passes down the fibre since light

is absorbed by impurities in the glass. If light travels through 75 km of glass, only

10% of the signal arrives at the other end.

(a) State any two advantages of using optical fibres for telecommunications

compared to copper wires. [1]

(b) Describe and explain, with the aid of a labelled diagram, how a light ray exitsfrom the optical fibre after travelling through 75 km of glass. [2]

(c) Explain how the difference in speed of light between glass and the claddingcauses total internal reflection to occur. You may use diagrams to help your explanation. [3]

(d) Calculate the refractive indexes of both glass and cladding, given that the

speeds of light in glass, cladding and vacuum are 2.1 x 108

m s-1

,2.5 x 108 m s-1 and 3.0 x 108 m s-1 respectively. [2]

(e) The relationship between the refractive indexes of two media is given by

r

i

n

n

i

r

sin

sin= , where nr represents the refractive index of the medium that

contains the refracted ray and ni represents the refractive index of the mediumthat contains the incident ray.

Calculate the minimal angle of incidence (to the nearest degree) for total internalreflection to take place in the core. [2]

END OF PAPER

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3e phy my 2010

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