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Secondary 2 Science Practice Paper 2
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TuitionGoWhere Practice Paper — Answer Key
Subject: Science (Secondary 2) Paper: Physical Sciences — Practice Paper (Version 2 of 5) Total Marks: 40
Section A: Multiple Choice (10 marks)
1. (c) Velocity [1]
- Velocity is a derived quantity (derived from displacement and time). Mass, time, and length are base quantities.
2. (c) 20 m/s [1]
- Using conservation of energy: mgh = ½mv² → gh = ½v² → v = √(2gh) = √(2 × 10 × 20) = √400 = 20 m/s.
- Common mistake: Students may forget to take the square root and select 40 m/s.
3. (b) Energy cannot be created or destroyed, only converted from one form to another. [1]
- This is the complete statement of the principle of conservation of energy.
4. (d) 100 J [1]
- Work done = mgh = 2 × 10 × 5 = 100 J.
5. (c) Watt [1]
- Power is measured in watts (W). Joule is the unit of energy, Newton is the unit of force, Pascal is the unit of pressure.
6. (c) 300 m [1]
- Distance = speed × time = 15 × 20 = 300 m.
7. (c) Elastic potential energy [1]
- A stretched spring stores elastic potential energy due to its deformation.
8. (c) 400 J [1]
- Useful output = efficiency × input = 0.80 × 500 = 400 J.
9. (b) Work = Force × Distance [1]
- Work done is the product of force and distance moved in the direction of the force.
10. (b) 5 m [1]
- Using conservation of energy: ½mv² = mgh → h = v²/(2g) = 100/(2 × 10) = 5 m.
- Alternatively, using v² = u² − 2gh with v = 0 at maximum height: 0 = 100 − 20h → h = 5 m.
Section B: Structured Questions (20 marks)
11.
(a) Kinetic energy is the energy a body possesses due to its motion. [1]
- Must mention "motion" or "movement." Simply saying "energy of a moving object" is acceptable.
(b) Gravitational potential energy is the energy stored in a body due to its position in a gravitational field (or height above a reference level). [1]
- Must mention "position/height" and "gravitational field" or equivalent.
12.
(a) Gain in gravitational potential energy = mgh = 50 × 10 × 6 = 3000 J [2]
- 1 mark for correct formula/substitution; 1 mark for correct answer with unit.
- Common mistake: Forgetting to include the unit (J).
(b) Power = Work done ÷ Time = 3000 ÷ 8 = 375 W [2]
- 1 mark for correct formula/substitution; 1 mark for correct answer with unit.
- Accept 375 J/s as equivalent to 375 W.
13.
(a) Work done = mgh = 200 × 10 × 12 = 24,000 J [2]
- 1 mark for correct formula/substitution; 1 mark for correct answer with unit.
(b) Power = Work ÷ Time = 24,000 ÷ 15 = 1600 W [2]
- 1 mark for correct formula/substitution; 1 mark for correct answer with unit.
14. The principle of conservation of energy states that energy cannot be created or destroyed, but can be converted from one form to another. The total amount of energy in a closed system remains constant. [2]
- 1 mark for stating that energy cannot be created or destroyed.
- 1 mark for stating that energy can be converted from one form to another (or that total energy remains constant).
- Both points must be present for full marks.
15.
(a) As the pendulum rises from B to A, kinetic energy is converted to gravitational potential energy. The speed decreases because the kinetic energy decreases as energy is transferred to potential energy. [2]
- 1 mark for identifying the energy conversion (kinetic → potential).
- 1 mark for explaining that the decrease in kinetic energy results in a decrease in speed.
(b) The total mechanical energy decreases over time. [1] This is because air resistance does work against the pendulum, converting some mechanical energy into thermal energy (heat). [1]
- 1 mark for stating that total mechanical energy decreases.
- 1 mark for explaining that air resistance converts mechanical energy to thermal energy.
Section C: Application and Data Response (10 marks)
16.
(a) Gravitational potential energy at P = mgh = 400 × 10 × 30 = 120,000 J [2]
- 1 mark for correct formula/substitution; 1 mark for correct answer with unit.
(b) Kinetic energy at P = 0 J [1]
- The car starts from rest, so its speed is 0 m/s and kinetic energy is zero.
(c) Using conservation of energy (no friction):
- At P: Total energy = GPE + KE = 120,000 + 0 = 120,000 J
- At Q: GPE = 0 (ground level), so all energy is kinetic
- ½mv² = 120,000 → ½ × 400 × v² = 120,000 → v² = 600 → v = 24.5 m/s (or √600 ≈ 24.49 m/s) [3]
- 1 mark for stating conservation of energy principle.
- 1 mark for correct substitution.
- 1 mark for correct answer (accept 24.5 m/s or 24.49 m/s).
(d) Yes, the car will reach point R. [1] At point P, the total energy is 120,000 J. At point R, the GPE required is mgh = 400 × 10 × 15 = 60,000 J. Since 120,000 J > 60,000 J, the car has sufficient energy to reach point R. [1]
- 1 mark for correct conclusion (yes).
- 1 mark for showing that total energy at P exceeds GPE required at R.
17.
(a) Useful work output = mgh = 5 × 10 × 2 = 100 J [2]
- 1 mark for correct formula/substitution; 1 mark for correct answer with unit.
(b) Total work input = Force × Distance = 30 × 4 = 120 J [2]
- 1 mark for correct formula/substitution; 1 mark for correct answer with unit.
(c) Efficiency = (Useful output ÷ Total input) × 100% = (100 ÷ 120) × 100% = 83.3% [2]
- 1 mark for correct formula/substitution; 1 mark for correct answer (accept 83% or 83.3%).
(d) Friction in the pulley system / Weight of the rope / Energy lost as heat/sound [1]
- Any one valid reason. Friction is the most common and expected answer.
End of Answer Key