5116 Prelim P2 St Patrick 09

NAME

CLASS

INDEX NO.

ST. PATRICK'S SCHOOL PRELIMINARY EXAMINATIONS 2009 SUBJECT :

SCIENCE (PHYSICS) 5116 PAPER 2

DATE

LEVEL

SECONDARY 4 EXPRESS / 5 NORMAL (ACADEMIC)

DURATION :

:

:

24 Aug 2009

1 HR 15 MINS

INSTRUCTIONS TO CANDIDATES DO NOT OPEN THIS BOOKLET UNTIL YOU ARE TOLD TO DO SO. 1. 2. 3. 2. 3.

Write your name, class and index number on the Question Paper. Answer All questions in Section A, with all necessary working in the space provided. Answer any two questions in Section B, and write your answers on the fulscap paper provided. Calculators may be used where necessary. Where numerical answers are not exact, give answers to Three (3) significant figures. DO NOT DETACH any sections from this paper and TIE all foolscap paper used with this paper.

INFORMATION FOR CANDIDATES: The number of marks is given in brackets [ ] at the end of each question. Take acceleration due to gravity, g = 10 m/s2. For Examiner’s Use Only Section

A (45 m)

B (20 m)

Total (65 m)

Grade

Score Teacher’s comments (if any): _________________________________ Parent’s / Guardian’s Signature: ___________________ Date: ___________

This question paper consists of 12

printed pages including this cover page

Science (Physics) 2009

Sec 4E/5N

SECTION A : [45 marks] Answer ALL questions in this section. Show all relevant working and write your answers in the space provided. 1

The figure below shows the velocity-time graph of the motion of a motor-cyclist. Velocity/m

18

Time/s 5

20

30

a)

Calculate the distance travelled by the motor-cyclist in the first 30 s? [1]

b)

If another motor-cyclist started from rest from the same starting point with a constant acceleration, what would be the magnitude of the acceleration of the second motor-cyclist if i) this motor-cyclist reached the same speed 20 s after starting? [2]

ii)

the distance travelled in the first 20 s of their motion by both motorcyclists are the same? [2]

2

Science (Physics) 2009

2

Sec 4E/5N

The figure below shows a car moving along the horizontal road.

Air resistance

Friction

Forward driving force

The car has a mass 800 kg. At one point in its motion, when the combined forces of air resistance and friction acting backwards are 400 N, its acceleration is 1.4 m/s2. a)

Calculate the forward driving force from the engine required to accelerate the car. [2]

Forward Driving Force = _______________________

b)

With the engine working at constant full power, the car’s acceleration decreases as it goes faster. Explain why this is so. [2] ___

3

a)

Explain what is meant by the moment of a force.

[1]

3

Science (Physics) 2009

b)

Sec 4E/5N

A uniform plank AB of length 4.0 m and weight 600 N is suspended by a vertical rope at each end. A box of 400 N is placed in the position shown in the diagram below.

4.0 m i)

ii)

4

Mark and label on the diagram, the forces acting on the plank due to the tension in the ropes, the weight of the box and the weight of the plank. [1] By taking moments about A, calculate the tension in the rope supporting the end B. [3]

A car of weight 8000 N is driven at constant speed through a distance of 800 m along a slope which rises 1 m in vertical height for every 8 m distance travelled along the slope. 8m 1m

a)

i)

Calculate the vertical height travelled by the car when it has traveled 800 m up the slope. [1]

4

Science (Physics) 2009

b)

5

a)

Sec 4E/5N

ii)

Calculate the gravitational potential energy gained by the car.

[1]

i)

State the work done by the engine of the car to drive it to this height at a constant speed of 8 m/s, assuming no energy is lost due to friction. [1]

ii)

Calculate the force exerted by the engine to drive the car at the constant speed of 8 m/s up the slope. [1]

iii)

Hence or otherwise, calculate the maximum power of the car.

[2]

The diagram below shows a very small bright light at S shining into a darkened room through a window set in a vertical wall.

S

•

wall window

wall

i)

Floor

Draw 2 rays on the diagram above to show the limits of the bright patch on the floor. [1]

5

Science (Physics) 2009

ii)

b)

Sec 4E/5N

What property of light rays does this example demonstrate?

[1]

The window is now covered with a plane mirror as shown.

S•

wall mirror

wall

Floor

Show how 2 rays from S are reflected by the mirror and use them to locate the image of S. Mark clearly the position of this image and labelled it I. [2]

6

An object of height 2.0 cm is placed on the principal axis of a converging lens. It produces a real and inverted mage of height 3.0 cm when placed at a distance of 5.0 cm from the lens. a) Choose a suitable scale and construct a ray diagram to show how the image is formed. Label the lens L and the principal focus F. [4]

b)

Determine the focal length of the converging lens.

[1]

………………………………………………………………………………………..

6

Science (Physics) 2009

7

Sec 4E/5N

The figure below shows a simple form of solar oven. A cup of water is put into the oven.

a)

Explain why the following increases the temperature of the oven.

[4]

i)

The position of the hinged board needs to be altered from time to time.

ii)

A wooden case is used.

iii)

A glass top is used.

iv)

The interior surface of the wooden case is blackened.

7

Science (Physics) 2009

8

Sec 4E/5N

b)

Suggest one way of increasing the power of the oven.

[1]

c)

Suggest one disadvantage of using the oven.

[1]

The graph below shows how the temperature of some liquid in a beaker changed as it was heated until it was boiling. Temperature / °C

Time / minutes

a)

b)

c)

What was the boiling point of the liquid?

[1]

State and explain what difference, if any, there would be in the final temperature if the liquid was heated more strongly. [2]

State one difference between boiling and evaporation.

[1]

8

Science (Physics) 2009

9

Sec 4E/5N

Six identical lamps, each with a resistance of 2 Ω, are connected to a 3 V cell as shown in the diagram below. Z

Y

W

X

a)

Calculate the effective resistance across WY.

[2]

b)

On the diagram, indicate the direction of the current in the circuit.

[1]

c)

What is the current that flows through point Z ?

[1]

d)

A voltmeter is connected across X and Y. What would be its reading? [1]

e)

A copper wire is connected between points W and Y. Describe and explain your observation. [1]

9

Science (Physics) 2009

Sec 4E/5N

SECTION B ( 20 marks ) Answer any two questions. Write your answers on the foolscap paper provided 10

a)

The graph shows how the speed of sound in air varies with temperature. Speed / ms-1

i) ii) iii) iv) v)

b)

Suggest a reason why the speed of sound in air increases with increasing temperature. [1] What is the speed of sound at 20 °C? [1] A sound of frequency 170 Hz is emitted by a loudspeaker. What will be the wavelength of the sound at 20 °C? [2] How will the wavelength of the sound emitted by the loudspeaker in (iii) change if the air temperature rises? [1] Supersonic aircraft cruises in the high atmosphere where the temperature is at -50 °C. What is the speed of the aircraft if it travels at twice the speed of sound? [2]

The figure below shows the waveforms of two musical notes X and Y shown on a CRO.

Explain briefly, which note has i) a higher pitch, ii) a louder sound, and iii) a greater speed in air.

[1] [1] [1]

10

Science (Physics) 2009

11

Sec 4E/5N

The diagram below shows a water heater rated at 2.5 kW which operates from 240 V a.c. supply.

L N

a) b) c) d) e) f)

12

a)

Calculate the current in the heating element. [2] Suggest the rating of a fuse that can be used to protect the heater. [1] Copy the diagram above and complete it to include the earth wire, a fuse and a switch. [2] [2] State and explain the use of the earth wire. [1] State the colour code of the live wire. Calculate the cost of heating the water if it took 4 minutes to boil and 1 kWh of electricity costs $0.55. [2]

The figure below shows a reed switch that consists of two springy contacts made of iron that are placed in a glass tube.

When a magnet is placed close to the two contacts, the two contacts become magnetized and attracted to each other. This allows an electrical current to pass through. The reed switch is placed in a motor circuit as shown in the figure below. Two permanent magnets X and Y rigidly attached to a circular coil are allowed to spin freely in a circular manner. The shaded portion of the magnet is the North Pole.

11

Science (Physics) 2009

Sec 4E/5N

The two permanent magnets are given a slight push such that they move in a clockwise direction as in the diagram. When magnet X reaches point P, the two contacts of the reed switch are magnetised. i) State what happens to the light bulb. [1] ii)

Explain what happens to magnet Y.

iii)

Describe what happens to the light bulb over a period of time. Explain your observations.

b)

[2]

[2]

The diagram below shows an electric circuit that contains four resistors. Three switches S1, S2 and S3 are opened. 10 A

15 A

i) ii) iii) iv)

S1

5Ω

S2

10 Ω

S3

10 Ω

B

[1] When switch S1 is closed, what is the ammeter reading? When switch S1 and S2 are closed, what is the ammeter reading? [2] List the switches that must be closed in order to obtain maximum reading of the ammeter. [1] If an infinite number of resistors is added in parallel across point A and B, deduce the eventual reading of the ammeter? [1]

------ End of Paper -----

12