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Secondary 4 Combined Science Physics Preliminary Examination Paper 5

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TuitionGoWhere Practice Paper - Combined Science Physics Secondary 4

TuitionGoWhere Exam Practice (AI)

Subject: Combined Science (Physics)
Level: Secondary 4
Paper: Prelim Practice (Version 5)
Duration: 1 hour 15 minutes
Total Marks: 65
Name: __________________________
Class: __________________________
Date: __________________________

Instructions to Candidates

Write your name, class, and date in the spaces provided.
Answer all questions.
Write your answers in the spaces provided in this booklet.
The number of marks is given in brackets [ ] at the end of each question or part question.
You may use a calculator.
Take $g = 10 \text{ m/s}^2$ .

Section A: Multiple Choice & Short Structured Questions

Answer all questions in this section.

1. A student measures the time for 20 complete oscillations of a simple pendulum. The stopwatch reading is 34.0 s. What is the period of the pendulum?

A 0.59 s
B 1.70 s
C 34.0 s
D 680 s

[1]

2. Which of the following quantities is a vector?

A Mass
B Speed
C Distance
D Acceleration

[1]

3. The graph shows the speed-time graph for a car moving along a straight road.

(Imagine a graph: Speed increases linearly from 0 to 20 m/s in 10s, stays constant at 20 m/s for 10s, then decreases linearly to 0 in 5s)

Calculate the total distance travelled by the car.

[2]

4. A box of mass 5.0 kg is pushed across a horizontal floor at a constant speed of 2.0 m/s. The pushing force is 15 N.

(a) State the magnitude of the frictional force acting on the box.
........................................................................................................................... [1]

(b) Explain your answer to (a).
...........................................................................................................................
........................................................................................................................... [1]

5. A diver jumps from a diving board. As she falls, her gravitational potential energy decreases and her kinetic energy increases.

Explain why the increase in kinetic energy is slightly less than the decrease in gravitational potential energy.

...........................................................................................................................
...........................................................................................................................
........................................................................................................................... [2]

6. The diagram shows a ray of light entering a glass block from air.

(Imagine a diagram: Ray enters glass block at an angle. Normal is drawn. Angle of incidence is 40°. Angle of refraction is 25°.)

(a) State the value of the angle of incidence.
........................................................................................................................... [1]

(b) Calculate the refractive index of the glass.

[2]

7. Which region of the electromagnetic spectrum has the longest wavelength?

A Gamma rays
B Microwaves
C Ultraviolet
D Visible light

[1]

8. A plastic rod is rubbed with a cloth and becomes positively charged.

Explain, in terms of electron transfer, how the rod becomes positively charged.

9. The circuit diagram shows a battery connected to two resistors in series. $R_1 = 4.0 \, \Omega$ and $R_2 = 6.0 \, \Omega$ . The battery voltage is 12 V.

Calculate the current flowing through the circuit.

[3]

10. A fuse is rated at 3 A.

Explain the purpose of a fuse in a electrical circuit.

Section B: Structured Questions

Answer all questions in this section.

11. A cyclist travels along a straight path. The distance-time graph for the journey is shown below.

(Imagine a graph: Distance (m) vs Time (s). From t=0 to t=10s, distance goes from 0 to 50m linearly. From t=10s to t=20s, distance stays at 50m. From t=20s to t=30s, distance goes from 50m to 110m linearly.)

(a) Describe the motion of the cyclist between $t = 10 \text{ s}$ and $t = 20 \text{ s}$ .
........................................................................................................................... [1]

(b) Calculate the speed of the cyclist between $t = 0 \text{ s}$ and $t = 10 \text{ s}$ .

[2]

[3]

12. A student investigates the specific heat capacity of aluminium. He uses an immersion heater to heat a 1.0 kg aluminium block.

The heater has a power of 50 W. The student records the temperature of the block every minute.

Time (min)	Temperature (°C)
0	20.0
1	22.5
2	25.0
3	27.5
4	30.0

(a) Calculate the energy supplied by the heater in 4 minutes.

[2]

(b) Calculate the specific heat capacity of aluminium using the data from the table.

[3]

(c) The student repeats the experiment but wraps the aluminium block in insulation. Suggest why the calculated specific heat capacity might be more accurate with insulation.

13. The diagram shows a converging lens forming an image of an object. The focal length of the lens is 10 cm. The object is placed 15 cm from the lens.

(Imagine a ray diagram setup: Object arrow at 15cm, Lens at 0cm, Focal points at 10cm and -10cm.)

(a) On the diagram provided in your mind (or sketch roughly), draw two rays from the top of the object to locate the image.
(Note: In a real exam, you would draw on the paper. Here, describe the position and nature of the image.)

Position of image: .................................................................................... [1]
Nature of image (Real/Virtual, Upright/Inverted, Magnified/Diminished):
........................................................................................................................... [2]

(b) State one practical application of a converging lens used in this configuration (object between F and 2F).

........................................................................................................................... [1]

14. A transformer is used to step down the voltage from 240 V to 12 V for a laptop charger.

(a) The primary coil has 1000 turns. Calculate the number of turns on the secondary coil.

[2]

(b) Explain why a transformer does not work with direct current (d.c.).

15. A balloon is rubbed against a wool sweater and becomes negatively charged. When the balloon is brought near a neutral wall, it sticks to the wall.

Explain this phenomenon using the concept of electrostatic induction.

Section C: Free Response Questions

Answer all questions in this section.

16. A car of mass 1200 kg is travelling at 20 m/s. The driver sees an obstacle and applies the brakes. The car comes to a stop in 4.0 seconds.

(a) Calculate the deceleration of the car.

[2]

(b) Calculate the braking force acting on the car.

[2]

[2]

(d) State what happens to this kinetic energy when the car stops.

........................................................................................................................... [1]

17. The diagram below shows a circuit containing a thermistor and a fixed resistor connected in series to a 12 V supply. A voltmeter is connected across the thermistor.

(Imagine circuit: Battery 12V -> Thermistor -> Resistor (100 Ohms) -> Back to Battery. Voltmeter in parallel with Thermistor.)

The resistance of the thermistor decreases as the temperature increases.

(a) Explain what happens to the reading on the voltmeter as the temperature of the thermistor increases.

(b) If the resistance of the thermistor is 200 $\Omega$ at 20°C, calculate the current in the circuit.

[3]

18. Sound waves and light waves are both waves, but they have different properties.

(a) State one similarity between sound waves and light waves.

........................................................................................................................... [1]

(b) State one difference between sound waves and light waves regarding their propagation.

........................................................................................................................... [1]

(c) An echo is heard 0.5 seconds after a shout is made near a cliff. The speed of sound in air is 340 m/s. Calculate the distance to the cliff.

[3]

19. A student sets up an experiment to verify the Principle of Moments. A uniform metre rule is pivoted at the 50 cm mark. A weight of 2.0 N is hung at the 20 cm mark.

(a) Calculate the moment of the 2.0 N weight about the pivot.

[2]

(b) Where must a 3.0 N weight be hung on the other side of the pivot to balance the rule?

[3]

20. A nuclear power station generates electricity using nuclear fission.

(a) Describe the process of nuclear fission.

(b) State one advantage and one disadvantage of nuclear power compared to fossil fuels.

Advantage: ....................................................................................................
Disadvantage: ............................................................................................... [2]

End of Paper

Answers

TuitionGoWhere Practice Paper - Combined Science Physics Secondary 4

Answer Key & Marking Scheme (Version 5)

Section A

1. B
Working: Period $T = \frac{\text{Total Time}}{\text{Number of Oscillations}} = \frac{34.0}{20} = 1.70 \text{ s}$ . [1]

2. D
Reasoning: Acceleration has both magnitude and direction. Mass, speed, and distance are scalars. [1]

3. 350 m
Working:
Distance = Area under graph.
Area 1 (Triangle): $\frac{1}{2} \times 10 \times 20 = 100 \text{ m}$
Area 2 (Rectangle): $10 \times 20 = 200 \text{ m}$
Area 3 (Triangle): $\frac{1}{2} \times 5 \times 20 = 50 \text{ m}$
Total Distance = $100 + 200 + 50 = 350 \text{ m}$ . [2]
(1 mark for correct method/areas, 1 mark for final answer)

4.
(a) 15 N [1]
(b) The box is moving at constant speed, which means acceleration is zero. According to Newton's First Law, the net force is zero. Therefore, the frictional force must be equal in magnitude and opposite in direction to the pushing force. [1]
(Accept: "Forces are balanced" or "Equilibrium")

5. Some energy is lost/dissipated as heat (thermal energy) and sound due to air resistance (drag). [2]
(1 mark for identifying air resistance/friction, 1 mark for energy dissipation form)

6.
(a) 40° [1]
(b) $n = \frac{\sin i}{\sin r} = \frac{\sin 40^\circ}{\sin 25^\circ} = \frac{0.6428}{0.4226} \approx 1.52$ [2]
(1 mark for formula/substitution, 1 mark for answer)

7. B
Reasoning: Order of wavelength (long to short): Radio, Microwave, IR, Visible, UV, X-ray, Gamma. [1]

8. Electrons are transferred from the plastic rod to the cloth. [1]
Since electrons are negatively charged, the loss of electrons leaves the rod with a net positive charge. [1]

9. 1.2 A
Working:
Total Resistance $R_T = R_1 + R_2 = 4.0 + 6.0 = 10.0 \, \Omega$ [1]
Current $I = \frac{V}{R} = \frac{12}{10} = 1.2 \text{ A}$ [2]
(1 mark for R total, 1 mark for I calculation)

10. A fuse contains a thin wire that melts [1] when the current exceeds the rated value, breaking the circuit and preventing overheating/fire. [1]

Section B

11.
(a) The cyclist is stationary (at rest). [1]
(b) Speed = $\frac{\text{Distance}}{\text{Time}} = \frac{50 - 0}{10 - 0} = \frac{50}{10} = 5.0 \text{ m/s}$ . [2]
(1 mark for substitution, 1 mark for answer with units)
(c) Total Distance = 110 m. Total Time = 30 s.
Average Speed = $\frac{110}{30} = 3.67 \text{ m/s}$ (or $3.7 \text{ m/s}$ ). [3]
(1 mark for total dist, 1 mark for total time, 1 mark for final answer)

12.
(a) Time = 4 min = $4 \times 60 = 240 \text{ s}$ .
Energy $E = P \times t = 50 \times 240 = 12,000 \text{ J}$ . [2]
(1 mark for time conversion, 1 mark for calculation)
(b) $\Delta T = 30.0 - 20.0 = 10.0^\circ\text{C}$ .
$E = mc\Delta T \Rightarrow 12,000 = 1.0 \times c \times 10.0$
$c = \frac{12,000}{10} = 1,200 \text{ J/(kg}^\circ\text{C)}$ . [3]
(1 mark for $\Delta T$ , 1 mark for rearrangement, 1 mark for answer)
(c) Insulation reduces heat loss to the surroundings, ensuring more of the heater's energy goes into heating the aluminium block. [1]

13.
(a) Position: Beyond 2F on the other side (or > 20 cm from lens). [1]
Nature: Real, Inverted, Magnified. [2]
(1 mark for Real/Inverted, 1 mark for Magnified)
(b) Projector / Slide Projector / Cinema Projector. [1]

14.
(a) $\frac{N_p}{N_s} = \frac{V_p}{V_s} \Rightarrow \frac{1000}{N_s} = \frac{240}{12}$
$\frac{1000}{N_s} = 20 \Rightarrow N_s = \frac{1000}{20} = 50 \text{ turns}$ . [2]
(1 mark for formula/substitution, 1 mark for answer)
(b) Transformers work on electromagnetic induction, which requires a changing magnetic field. [1]
Direct current produces a constant magnetic field, so no voltage is induced in the secondary coil. [1]

15.
The negatively charged balloon repels electrons in the wall surface. [1]
This leaves a positive charge on the surface of the wall (induction). [1]
The opposite charges (negative balloon and positive wall surface) attract each other, causing the balloon to stick. [1]

Section C

16.
(a) $a = \frac{v - u}{t} = \frac{0 - 20}{4.0} = -5.0 \text{ m/s}^2$ .
Deceleration = $5.0 \text{ m/s}^2$ . [2]
(1 mark for calculation, 1 mark for positive magnitude)
(b) $F = ma = 1200 \times 5.0 = 6000 \text{ N}$ . [2]
(1 mark for formula, 1 mark for answer)
(c) $KE = \frac{1}{2}mv^2 = \frac{1}{2} \times 1200 \times (20)^2 = 600 \times 400 = 240,000 \text{ J}$ (or 240 kJ). [2]
(1 mark for formula/sub, 1 mark for answer)
(d) Converted to heat (thermal energy) in the brakes and surroundings. [1]

17.
(a) As temperature increases, resistance of thermistor decreases. [1]
Total resistance of circuit decreases, so current increases. [1]
However, since the thermistor resistance decreases relative to the fixed resistor, the voltage share across the thermistor decreases (Voltmeter reading drops). [1]
(Alternative logic: $V_{thermistor} = V_{supply} \times \frac{R_{thermistor}}{R_{total}}$ . As $R_{thermistor}$ drops, the fraction drops.)
(b) $R_{total} = R_{thermistor} + R_{fixed} = 200 + 100 = 300 \, \Omega$ .
$I = \frac{V}{R} = \frac{12}{300} = 0.04 \text{ A}$ . [3]
(1 mark for total R, 1 mark for formula, 1 mark for answer)

18.
(a) Both can be reflected / refracted / diffracted / carry energy. [1]
(b) Sound requires a medium to travel; light can travel through a vacuum. [1]
(c) Total distance travelled by sound = $v \times t = 340 \times 0.5 = 170 \text{ m}$ .
Distance to cliff = $\frac{170}{2} = 85 \text{ m}$ . [3]
(1 mark for total dist, 1 mark for dividing by 2, 1 mark for answer)

19.
(a) Distance from pivot = $50 - 20 = 30 \text{ cm} = 0.3 \text{ m}$ .
Moment = $Force \times Distance = 2.0 \times 0.3 = 0.6 \text{ Nm}$ . [2]
(1 mark for distance, 1 mark for moment)
(b) Clockwise Moment = Anticlockwise Moment.
$3.0 \times d = 0.6$
$d = \frac{0.6}{3.0} = 0.2 \text{ m}$ (or 20 cm).
Position = $50 \text{ cm} + 20 \text{ cm} = 70 \text{ cm}$ mark. [3]
(1 mark for principle, 1 mark for distance d, 1 mark for final position)

20.
(a) A heavy nucleus (e.g., Uranium-235) absorbs a neutron. [1]
It splits into two lighter nuclei (daughter nuclei) and releases 2-3 neutrons and energy. [1]
(b) Advantage: No greenhouse gas emissions / High energy density. [1]
Disadvantage: Radioactive waste disposal / Risk of accidents / High decommissioning cost. [1]