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O Level Combined Science Practice Paper 1
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Questions
TuitionGoWhere Practice Paper - Combined Science O-Level
TuitionGoWhere Secondary School (AI)
Subject: Combined Science
Level: O-Level
Paper: PRACTICE Paper 2 (Physics)
Duration: 1 hour 15 minutes
Total Marks: 65
Name: _________________ Class: _________ Date: _________
Instructions to Candidates
- Answer all questions in the spaces provided
- Show all working clearly for calculations
- 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 m/s²
Section A [25 marks]
1. Fig. 1.1 shows a simple pendulum consisting of a metal sphere suspended by a thin thread.
[Assume diagram shows pendulum at three positions: A (maximum left), B (center), C (maximum right)]
(a) State the principle of conservation of energy. [2]
(b) Complete the table below for the pendulum at positions A, B and C. Use the words maximum, minimum or zero. [3]
| Position | Kinetic Energy | Potential Energy |
|---|---|---|
| A | ||
| B | ||
| C |
(c) Draw a free-body diagram to show the forces acting on the sphere when it is at position B. [2]
(d) Explain why the pendulum eventually comes to rest. [2]
2. A student investigates how the rate of cooling of water depends on the surface area exposed to air.
Fig. 2.1 shows the apparatus used.
[Assume diagram shows two identical containers with different surface areas]
(a) State two variables that must be kept constant in this investigation. [2]
(i) _________________________________________________________________
(ii) _________________________________________________________________
(b) The student records the temperature every 2 minutes for 20 minutes. Suggest how the student can improve the reliability of the results. [2]
(c) Explain how heat is lost from the water surface by convection. [3]
3. A girl of weight 450 N climbs a vertical ladder of height 8.0 m in 25 s.
(a) Calculate the work done against gravity. [2]
Working: _________________________________________________
Answer: _________________ J
(b) Calculate the power developed by the girl. [2]
Working: _________________________________________________
Answer: _________________ W
(c) The girl then slides down a fireman's pole of the same height in 5.0 s. Calculate her average speed during the descent. [2]
Working: _________________________________________________
Answer: _________________ m/s
4. Fig. 4.1 shows a ray of light traveling from glass into air.
[Assume diagram shows incident ray, refracted ray, and normal]
(a) On Fig. 4.1, label the angle of incidence i and the angle of refraction r. [2]
(b) The refractive index of glass is 1.5. The angle of incidence is 30°. Calculate the angle of refraction. [3]
Working: _________________________________________________
Answer: _________________ °
(c) State what happens to the light ray when the angle of incidence exceeds the critical angle. [1]
Section B [40 marks]
5. A student uses the apparatus shown in Fig. 5.1 to investigate the relationship between current and voltage for a metal wire.
[Assume diagram shows circuit with ammeter, voltmeter, variable resistor, and metal wire]
(a) State the name of component X in the circuit. [1]
(b) Explain why component X is needed in this circuit. [2]
(c) The student obtains the following results:
| Voltage (V) | 0.0 | 1.0 | 2.0 | 3.0 | 4.0 | 5.0 |
|---|---|---|---|---|---|---|
| Current (A) | 0.0 | 0.2 | 0.4 | 0.6 | 0.8 | 1.0 |
(i) Plot a graph of current (y-axis) against voltage (x-axis) on the grid below. [3]
[Assume grid provided]
(ii) State the relationship between current and voltage shown by your graph. [1]
(iii) Use your graph to find the resistance of the metal wire. Show your working. [3]
Working: _________________________________________________
Answer: _________________ Ω
(d) The student repeats the experiment using a different metal wire of the same material but with twice the length. Predict how this would affect the resistance. Explain your answer. [3]
6. Fig. 6.1 shows a ray box being used to investigate refraction of light through a glass block.
[Assume diagram shows ray box, glass block, and protractor]
(a) The student measures the angle of incidence and angle of refraction for different positions of the ray box. Explain why the student should take readings for at least five different angles of incidence. [2]
(b) The table shows the student's results:
| Angle of incidence (°) | 10 | 20 | 30 | 40 | 50 |
|---|---|---|---|---|---|
| Angle of refraction (°) | 7 | 13 | 19 | 25 | 30 |
(i) Use the data to calculate the refractive index of glass for an angle of incidence of 30°. [3]
Working: _________________________________________________
Answer: _________________
(ii) Calculate the critical angle for this glass. [3]
Working: _________________________________________________
Answer: _________________ °
(c) A ray of light in the glass hits the glass-air boundary at an angle of incidence of 50°.
(i) State what happens to this ray. [1]
(ii) Explain your answer to (c)(i). [2]
7. A metal sphere is suspended from a spring as shown in Fig. 7.1.
[Assume diagram shows sphere hanging from spring in equilibrium]
(a) The sphere has a weight of 5.0 N and is in equilibrium. State the size and direction of the force exerted by the spring on the sphere. [2]
Size: _________________ N Direction: _________________
(b) The sphere is now pulled down and released so that it oscillates vertically.
(i) State the energy changes that occur as the sphere moves from the lowest point to the highest point of its oscillation. [2]
(ii) Explain why the amplitude of oscillation gradually decreases. [2]
(c) The sphere completes 20 oscillations in 25 s.
(i) Calculate the frequency of oscillation. [2]
Working: _________________________________________________
Answer: _________________ Hz
(ii) Calculate the period of oscillation. [2]
Working: _________________________________________________
Answer: _________________ s
8. A student investigates how the extension of a spring varies with the applied force.
(a) Describe how the student could carry out this investigation safely. Include details of the measurements to be taken. [4]
(b) The student obtains the following results:
| Force (N) | 0.0 | 1.0 | 2.0 | 3.0 | 4.0 | 5.0 |
|---|---|---|---|---|---|---|
| Extension (cm) | 0.0 | 2.5 | 5.0 | 7.5 | 10.0 | 12.5 |
(i) State the relationship between force and extension shown by these results. [1]
(ii) Calculate the spring constant. Include the unit in your answer. [3]
Working: _________________________________________________
Answer: _________________
(iii) Use your answer to (b)(ii) to calculate the extension when a force of 3.5 N is applied. [2]
Working: _________________________________________________
Answer: _________________ cm
END OF PAPER
Answers
TuitionGoWhere Practice Paper - Combined Science O-Level (Marking Scheme)
Section A [25 marks]
1. Pendulum energy and forces [11 marks]
(a) State the principle of conservation of energy. [2] Answer: Energy cannot be created or destroyed, only converted from one form to another [1]. In a closed/isolated system, total energy remains constant [1].
(b) Complete the table [3]
| Position | Kinetic Energy | Potential Energy |
|---|---|---|
| A | Zero [1] | Maximum [1] |
| B | Maximum | Minimum/Zero |
| C | Zero | Maximum [1] |
(c) Free-body diagram at position B [2] Answer: Arrow pointing vertically downward labeled Weight/W [1]. Arrow pointing vertically upward labeled Tension/T [1]. Both arrows should be same length and from center of sphere.
(d) Why pendulum comes to rest [2] Answer: Energy is lost due to air resistance/friction [1]. Kinetic energy is converted to heat/thermal energy [1].
2. Cooling investigation [9 marks]
(a) Two constant variables [2] Answer: Any two from: initial temperature of water [1], volume of water [1], room temperature, material of container, time intervals
(b) Improve reliability [2] Answer: Take repeat readings and calculate average [1]. Use more accurate thermometer/take readings more frequently [1].
(c) Heat loss by convection [3] Answer: Warm air above water surface rises [1] because it is less dense than cooler air [1]. Cooler air moves in to replace it, creating convection currents [1].
3. Work and power calculations [6 marks]
(a) Work done against gravity [2] Working: Work = Weight × height = 450 N × 8.0 m [1] Answer: 3600 J [1]
(b) Power developed [2] Working: Power = Work ÷ time = 3600 J ÷ 25 s [1] Answer: 144 W [1]
(c) Average speed during descent [2] Working: Speed = distance ÷ time = 8.0 m ÷ 5.0 s [1] Answer: 1.6 m/s [1]
4. Light refraction [6 marks]
(a) Label angles [2] Answer: Angle i correctly labeled between incident ray and normal [1]. Angle r correctly labeled between refracted ray and normal [1].
(b) Calculate angle of refraction [3] Working: n = sin i / sin r, so sin r = sin i / n [1] sin r = sin 30° / 1.5 = 0.5 / 1.5 = 0.333 [1] Answer: r = 19.5° (accept 19-20°) [1]
(c) What happens beyond critical angle [1] Answer: Total internal reflection occurs [1]
Section B [40 marks]
5. Current-voltage investigation [13 marks]
(a) Name of component X [1] Answer: Variable resistor/rheostat [1]
(b) Why component X is needed [2] Answer: To vary/control the voltage across the wire [1]. To obtain a range of readings [1].
(c)(i) Graph plotting [3] Answer: Correct axes labeled with units [1]. Points plotted accurately [1]. Straight line through origin [1].
(c)(ii) Relationship [1] Answer: Current is directly proportional to voltage / Current increases linearly with voltage [1]
(c)(iii) Calculate resistance [3] Working: Resistance = voltage ÷ current [1] Using any point: R = 5.0 V ÷ 1.0 A [1] Answer: 5.0 Ω [1]
(d) Effect of doubling length [3] Answer: Resistance would double/increase [1]. Longer wire has more resistance [1]. Resistance is proportional to length [1].
6. Refraction investigation [13 marks]
(a) Why take five different angles [2] Answer: To check for pattern/relationship [1]. To identify any anomalous results [1].
(b)(i) Calculate refractive index [3] Working: n = sin i / sin r [1] n = sin 30° / sin 19° = 0.5 / 0.326 [1] Answer: n = 1.53 (accept 1.5-1.6) [1]
(b)(ii) Calculate critical angle [3] Working: sin θc = 1/n [1] sin θc = 1/1.53 = 0.654 [1] Answer: θc = 40.8° (accept 40-41°) [1]
(c)(i) What happens at 50° incidence [1] Answer: Total internal reflection [1]
(c)(ii) Explain answer [2] Answer: 50° is greater than the critical angle (40.8°) [1]. So all light is reflected back into the glass [1].
7. Spring oscillations [12 marks]
(a) Force from spring [2] Answer: Size: 5.0 N [1]. Direction: Upward [1]
(b)(i) Energy changes [2] Answer: Kinetic energy converts to gravitational potential energy [1] and elastic potential energy [1].
(b)(ii) Why amplitude decreases [2] Answer: Energy is lost due to air resistance/friction [1]. Energy is converted to heat/thermal energy [1].
(c)(i) Calculate frequency [2] Working: Frequency = number of oscillations ÷ time = 20 ÷ 25 s [1] Answer: 0.8 Hz [1]
(c)(ii) Calculate period [2] Working: Period = 1 ÷ frequency = 1 ÷ 0.8 [1] Answer: 1.25 s [1]
8. Spring extension investigation [10 marks]
(a) Safe procedure [4] Answer: Clamp spring securely to stand [1]. Add masses gradually to avoid sudden extension [1]. Measure original length and extended length with ruler [1]. Calculate extension = extended length - original length [1]. Accept: wear safety glasses, use small masses
(b)(i) Relationship [1] Answer: Force is directly proportional to extension / Extension increases linearly with force [1]
(b)(ii) Calculate spring constant [3] Working: k = F/x, using any data point [1] k = 1.0 N ÷ 0.025 m = 40 N/m [1] Answer: 40 N/m [1]
(b)(iii) Extension for 3.5 N [2] Working: x = F/k = 3.5 N ÷ 40 N/m = 0.0875 m [1] Answer: 8.75 cm (accept 8.8 cm) [1]
Total: 65 marks
Grade Boundaries (Indicative):
- A: 55-65 marks
- B: 48-54 marks
- C: 40-47 marks
- D: 32-39 marks
- E: 26-31 marks