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Secondary 1 Science Practice Paper 2
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TuitionGoWhere Practice Paper – Science Secondary 1
Answer Key – Physical Sciences Practice Paper (Version 2 of 5)
Section A: Multiple Choice
1. (B) Newton [1]
The SI unit of force is the Newton (N). Joule is the unit of energy, Watt is the unit of power, and Kilogram is the unit of mass.
2. (B) Weight of the book and normal reaction force from the table [1]
When the book is at rest, the downward weight is balanced by the upward normal reaction force from the table. These are equal in magnitude and opposite in direction.
3. (B) Gravitational potential energy → Kinetic energy [1]
As the ball falls, its height decreases (losing gravitational potential energy) and its speed increases (gaining kinetic energy).
4. (C) Magnetic attraction between two magnets [1]
Magnetic force acts at a distance without physical contact. The other options (pushing, friction, tension) all require direct contact.
5. (C) 200 J [1]
Work done = Force × Distance = 50 N × 4 m = 200 J
6. (C) Energy cannot be created or destroyed, only converted. [1]
This is the Law of Conservation of Energy. Energy can change forms but the total amount remains constant.
7. (C) 4000 J [1]
Work done = Force × Distance = 500 N × 8 m = 4000 J
8. (B) Forces that are equal in magnitude and opposite in direction, acting on the same object [1]
Balanced forces result in no change in motion (no acceleration). They must act on the same object.
9. (B) Maximum kinetic energy and minimum gravitational potential energy [1]
At the lowest point, the pendulum has the greatest speed (maximum kinetic energy) and the lowest height (minimum gravitational potential energy).
10. (B) The rate of doing work [1]
Power = Work done ÷ Time taken. It measures how quickly work is done or energy is transferred.
Section B: Structured Questions
11.
(a) Work done = Force × Distance = 30 N × 5 m = 150 J [2]
[1 mark for correct formula/substitution; 1 mark for correct answer with unit]
(b) Kinetic energy → Thermal energy (heat) [1]
Friction between the block and the rough floor converts kinetic energy into thermal energy.
(c) Friction acts on the block in the opposite direction to motion [1], which does negative work on the block, converting its kinetic energy into thermal energy until the block stops [1]. [2]
[Award 1 mark for identifying friction; 1 mark for explaining energy conversion leading to the stop]
12.
(a) Kinetic energy at Y = 100 J [1]
By conservation of energy, all gravitational potential energy at X is converted to kinetic energy at Y (assuming no losses).
(b) The missing 15 J of energy has been converted into thermal energy (heat) due to friction between the ball and the slope, and some may also have been converted to sound energy [2].
[1 mark for identifying thermal energy; 1 mark for identifying the cause (friction) or an additional energy form]
(c) Law of Conservation of Energy (or Principle of Conservation of Energy) [1]
Energy cannot be created or destroyed; it can only be converted from one form to another.
13.
(a) Work done = Force × Distance = 600 N × 2.0 m = 1200 J [2]
[1 mark for correct substitution; 1 mark for correct answer with unit]
(b) Power = Work done ÷ Time = 1200 J ÷ 4 s = 300 W [2]
[1 mark for correct formula/substitution; 1 mark for correct answer with unit]
(c) Chemical energy (in muscles) → Gravitational potential energy (in barbell) [1]
The weightlifter's muscles convert chemical energy into gravitational potential energy as the barbell is raised.
14.
(a) Free-body diagram: [2]
← 20 N 20 N →
┌─────────────────────┐
│ │
│ BOX │
│ │
└─────────────────────┘
[1 mark for showing two equal and opposite horizontal forces; 1 mark for clear labels]
Note: Weight (downward) and normal reaction (upward) may also be shown for full marks if labelled.
(b) Yes, the box is in equilibrium [1] because the two forces are equal in magnitude and opposite in direction, so the resultant (net) force is zero [1]. [2]
[The box remains stationary as there is no unbalanced force acting on it.]
15.
(a) Work done = Force × Distance moved in the direction of the force. Since the suitcase is stationary, the distance moved is 0 m [1], therefore Work = 15 N × 0 m = 0 J [1]. [2]
[Work is only done when there is displacement in the direction of the applied force.]
(b) The person's muscles are still contracting and relaxing repeatedly to maintain the grip and hold the position [1]. Chemical energy in the muscles is being converted to thermal energy (heat) even though no mechanical work is done on the suitcase [1]. [2]
[Muscles consume energy internally to maintain tension, even without external displacement.]
Section C: Application and Reasoning
16.
(a) Gravitational potential energy = mgh = 400 kg × 10 N/kg × 30 m = 120,000 J (or 120 kJ) [2]
[1 mark for correct substitution; 1 mark for correct answer with unit]
(b) Kinetic energy at Q = 120,000 J [1]
All gravitational potential energy at P is converted to kinetic energy at Q (assuming no losses).
(c) In an ideal situation with no energy losses, the car can reach exactly 15 m on the second hill [1], because the gravitational potential energy at R (mgh = 400 × 10 × 15 = 60,000 J) is less than the total energy available (120,000 J), meaning the car would still have kinetic energy remaining and could theoretically reach 30 m. However, in reality, energy is lost to friction and air resistance, so the car cannot reach a point higher than 15 m [1]. [2]
[Award marks for correct energy comparison and recognition of real-world energy losses.]
17.
(a) As the angle of the ramp increases, the force needed to pull the block up also increases [1]. The relationship is that a larger angle requires a greater force — the force increases steadily (approximately linearly) with the angle [1]. [2]
[1 mark for identifying the trend; 1 mark for describing the nature of the relationship]
(b) The force needed at 60° would be approximately 38–40 N [1]. This is because the trend shows that for every 10° increase, the force increases by approximately 5–6 N. From 50° (34.0 N), adding about 5 N gives approximately 39 N [1]. [2]
[Accept any reasonable prediction between 37–41 N with valid reasoning based on the trend.]
(c) One of the following:
- Mass/weight of the block
- Surface texture of the ramp (same ramp used)
- Speed at which the block is pulled (constant speed)
- Same block used throughout [1]
[Any one valid controlled variable]
18. The cyclist is not doing work against gravity because there is no vertical displacement — the road is level, so the height does not change [1]. However, the cyclist is still expending energy because work is being done against friction and air resistance [1]. The chemical energy from the cyclist's muscles is converted into kinetic energy and thermal energy to overcome these resistive forces [1]. [3]
[1 mark for explaining no work against gravity; 1 mark for identifying resistive forces; 1 mark for energy conversion explanation]
19.
(a) As the ball rises, its kinetic energy decreases [1] and its gravitational potential energy increases [1]. At the maximum height, kinetic energy is zero and gravitational potential energy is maximum. [2]
[The ball slows down as it gains height — energy is converted from kinetic to gravitational potential.]
(b) As the ball falls, its gravitational potential energy decreases [1] and its kinetic energy increases [1]. The ball speeds up as it loses height. [2]
[Energy is converted back from gravitational potential to kinetic as the ball descends.]
20.
(a) The work done by Ali and Bala is the same [1] because work done = Force × Distance, and both carry the same mass (same weight/force) up the same height (same distance). Since both factors are identical, the work done is equal [1]. [2]
[Work done against gravity depends only on weight and vertical height, not on time taken.]
(b) Ali develops more power than Bala [1] because power = Work ÷ Time, and Ali completes the same amount of work in less time (20 s compared to 30 s). Since power is inversely proportional to time for the same work, Ali's power is greater [1]. [2]
[1 mark for correct comparison; 1 mark for correct reasoning involving time]
End of Answer Key