5116 Paper2 2009

Name : ______________________________(

)

Class : ____________

DAMAI SECONDARY SCHOOL PRELIMINARY EXAMINATION 2009

Secondary Four Express and Five Normal Academic Level SCIENCE (PHYSICS) PAPER 2 15th Sept 2009

8.00 – 9.15 a.m.

1 hour 15 minutes

INSTRUCTIONS TO CANDIDATES Write your full name, register number and class in the spaces provided on the cover of this question paper. Section A Answer all the questions. Write your answers in the spaces provided on the question paper. Section B Answer any two questions. Write your answers on the writing paper provided. Start each question on a fresh page. At the end of the examination, tie your answers together with the string provided. Submit Section A and Section B separately.

INFORMATION FOR CANDIDATES The number of marks is given in the brackets [

].

g = 10 N/kg Marks Section A Section B

Maximum 45 10 10

Total

65

_________________________________________________________________________ This question paper consists of 13 printed pages [Turn over]

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Section A: Short Structured Questions (45 marks) Answer all the questions in this section. Write your answers in the spaces provided. 1. A picture frame is held by two supporting forces as shown. Draw a scale vector diagram to determine the magnitude and direction of resultant force exerted by the two ropes. [4]

18 N 12 N 50° 30°

2

2. A uniform beam AC of weight 2 N and 3 m long is hinged freely at A. A string attached to the spring balance supports the beam at C as shown.

A

C

Weight a.

Calculate the tension T in the rope at C.

[2]

b.

An additional 1 kg mass is now hung 0.3 m to the right of end A. Calculate the new tension in the rope if the beam remains horizontal. [2]

3. Azri and David are playing football on a wet and soggy field. Most of the time, Azri manages to stay on his feet but David keeps slipping. A close inspection reveals that both have different sets of shoes on and that both of them have approximately the same weight.

Shoe Y

Shoe X

3

a. Which pair of shoes most likely belongs to Azri?

[1]

___________________________________________________ b. Explain, using the term 'pressure' why Shoe Y is better than Shoe X in a football match on a soggy field. [3] ________________________________________________________ ________________________________________________________ ________________________________________________________ ________________________________________________________

4. A girl of mass 40 kg runs up a flight of stairs to a floor at a height of 6 m in 10 s. Calculate a. the work done against gravity. [2]

b. the average power developed by the girl.

4

[2]

5. a. The time required to bake large potatoes in an oven may be significantly reduced if a long steel spike was placed through the center of each potato before putting them in an oven. Explain why this process reduces the cooking time. [2] ________________________________________________________ ________________________________________________________ ________________________________________________________ ________________________________________________________

b. Metals are good conductors of heat. Yet aluminium foil-coloured blankets can be used to keep mountaineers warm. Explain this statement. [2] ________________________________________________________ ________________________________________________________ ________________________________________________________ ________________________________________________________

5

6. Graph P shows the variation of the displacement of the medium particles along the wave at a particular time. Graph Q shows the variation of the displacement of the same wave with time at a particular point along the wave.

0.6 16 − 0.6 Graph P

0.6 4.0 4.0

− 0.6 0.6 Graph Q a. State values for i. the wavelength for the wave

[1]

______________________________ ii. the frequency of the wave

[1]

________________________________ b. Calculate the speed of the wave.

6

[2]

7. The diagram shows an object O and its image produced by a converging lens. By drawing 2 rays, mark on the diagram a. the position of the lens (label it L) [1] b. the position of the principal focus of the lens (label it F) [2]

I O

8. An experimenter at A found that the time taken by sound waves to travel to travel to a wall and return to A was 4.3 s. On walking 136 m to B and repeating the test, the experimenter found the corresponding time reduced to 3.5 s.

A

B 136 m Wall

a. Find the speed of sound in air from these observations.

b.

What is one characteristic of the wall for this experiment to be accurate?

[2]

[1]

________________________________________________________ ________________________________________________________

7

9. A charged light metal sphere is suspended between two parallel plates. The plates are connected to a d.c. power supply as shown in the figure below.

θ

a. What kind of charge is carried by the sphere? Explain your answer.[3] ________________________________________________________ ________________________________________________________ ________________________________________________________ ________________________________________________________

b. What happens to the deflection angle θ of the sphere from the vertical, as the voltage increases? [1] ______________________________________________________

10. The figure below shows the wiring of 2 sockets done by an unqualified electrical technician.

E L N a. Are the wrongly wired sockets wired in series or parallel?

[1]

________________________________________________________

8

b. In the figure below, construct lines to show how the two sockets should be connected such that two appliances plugged into them can work at their desired voltage of 240 V each. [2]

E

L

N

11. Draw the magnetic field lines between the two magnetic North poles in the space below. [2]

N

N

12. The diagram below shows a door lock which can be opened from a flat in a building. The steel bolt keeps the door locked.

9

a. Explain how the door is unlocked when the switch is closed.

[2]

__________________________________________________________ __________________________________________________________ __________________________________________________________ __________________________________________________________

b. Why is the spring needed in the lock?

[1]

__________________________________________________________ __________________________________________________________

13. A small plotting compass is placed above a copper wire as shown below. When there is no current in the wire, the plotting compass points in the direction shown.

a. A large current is now passed through the wire, causing the needle to deflect. Explain why the needle deflects and state the direction in which the arrow will now point. [2] ________________________________________________________ ________________________________________________________ ________________________________________________________ ________________________________________________________ b. The compass is now placed below the wire. State any changes you would expect to see in the needle’s deflection, if any. [1] ________________________________________________________ ________________________________________________________

10

Section B: Long Structured Questions (20 marks) Answer any 2 the questions in this section. Write your answers in the writing paper provided. 1. A car of mass 750 kg is accelerated from rest to 20 ms-1 in 5 sec on a dry straight road. It then travels at constant speed for the next 10 s after which the brakes are applied so that it comes to a stop in 2 s. a. Calculate the deceleration of the car during the last 2 s.

[2]

b. Calculate the resultant force acting on the car during the time when the brakes were applied. [2] c. “When the car is moving at constant speed, there are no forces acting on the car.” Do you agree with this statement? Why? [1] d. Sketch the speed-time graph of the car’s motion for the entire duration. Label your graph with all necessary values of speed and time. [3] e. Hence, calculate the total distance travelled by the car.

11

[2]

2. The figure shows 3 rays of light UR, PQ and TR as they enter a semi-circular glass block. Ray TR continues in the path TRS as shown.

α

30o

The speed of light in air is the same as the speed of light in a vacuum, which is 3.0 × 10 8 m s–1. The refractive index of glass is 1.5. a. Explain why there is no change in the direction of the ray as it enters the block at Q. [1] b. Light slows down when it enters an optically denser medium. Calculate the speed of light between Q and R. [2] c. Another ray passes along TR as shown. Calculate the angle, α, which the emerging ray makes with the normal after emerging from the glass. [2] d. A light ray passing along UR does not emerge from the glass block because its angle of incidence with the normal at R exceeds the critical angle. State what is meant by critical angle. [2] e. Sketch a diagram of the glass block and ray UR to show the path taken by the ray UR immediately after point R. [1] f.

Calculate the critical angle of the glass block.

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[2]

3. The figure below shows a circuit in which all the switches S1, S2 and S3 are open.

a. Calculate the effective resistance between points P and Q when S1, S2 and S3 are closed. [2] b. If the ammeter reading is 2.0 A, what is the resistance of the lamp when S1, S2 and S3 are closed? [2] c. What is the energy dissipated by the lamp in 1 minute when S1 is open with S2, and S3 closed and the current in the circuit is 2A? [2] d. With switches S1, S2 and S3 closed, the lamp lights up with a certain brightness. If switch S1 is now open, explain how this will affect the brightness of the lamp. [2] e. Calculate the effective resistance between points P and Q when S1 is now open, S2 and S3 are closed. [2]

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