Secondary 1 Science Practice Paper 5

TuitionGoWhere Practice Paper — Science Secondary 1

Answer Key — Physical Sciences (Forces, Energy & Work)

Paper: Practice Paper — Version 5 Total Marks: 40

Section A: Multiple Choice & Short Answer (20 marks)

1. B) 4 J [2]

Working: W = F × d = 5 N × 0.8 m = 4 J

Marking notes: Award 2 marks for correct answer B. Award 1 mark if the working shows W = F × d but the calculation is wrong. Common mistake: choosing A (confusing constant speed with zero work) or D (multiplying 5 × 8 incorrectly).

2. D) Joule [2]

Marking notes: Award 2 marks for D. Newton is the unit of force, Watt is the unit of power, Pascal is the unit of pressure.

3. Gravitational potential energy is converted to kinetic energy. [2]

Marking notes: Award 2 marks for a complete and correct statement identifying both energy forms. Award 1 mark if only one energy form is mentioned. Accept equivalent phrasing such as "GPE → KE" or "potential energy to kinetic energy."

4. Kinetic energy is the energy a body possesses due to its motion, whereas gravitational potential energy is the energy a body possesses due to its height above the ground (or position in a gravitational field). [2]

Marking notes: Award 2 marks for a clear, correct distinction. Award 1 mark for a partially correct answer (e.g., only defining one type of energy). Accept any valid difference.

5. 2400 J [2]

Working: GPE = mgh = 60 × 10 × 4.0 = 2400 J

Marking notes: Award 2 marks for correct answer with unit. Award 1 mark for correct working but wrong final answer or missing unit. Common mistake: using g = 9.8 instead of 10 (accept if consistent but note the question specifies g = 10 N/kg).

6. 0 J (zero joules) of work is done. [1] This is because although a force is applied to hold the bag, there is no displacement of the bag in the direction of the force. Work is only done when a force moves an object through a distance. [1]

Marking notes: Award 1 mark for stating 0 J. Award 1 mark for the explanation linking work to displacement. Common mistake: students may calculate W = 10 × 30 = 300 J, confusing force × time with force × distance.

7. The kinetic energy is converted to gravitational potential energy. [2]

Marking notes: Award 2 marks for a complete and correct statement. Award 1 mark if only "gravitational potential energy" is stated without mentioning the conversion. Accept "KE → GPE."

8. Power is the rate of doing work (or the rate of energy transfer). [2]

Marking notes: Award 2 marks for a correct definition. Accept "Power = Work done ÷ Time taken" or "Power = Energy transferred ÷ Time taken." Award 1 mark for a partially correct answer (e.g., only stating the formula without words).

9. 80% (or 0.8) [2]

Working: Efficiency = (Useful energy output ÷ Total energy input) × 100% Efficiency = (200 ÷ 250) × 100% = 80%

Marking notes: Award 2 marks for correct answer with percentage. Award 1 mark for correct working but wrong final answer. Accept answer as a decimal (0.8) or fraction (4/5). Common mistake: inverting the fraction (250/200 = 125%).

10. (a) A [1] (b) B [1]

Marking notes: Award 1 mark each. At the highest point (A), the bob has maximum height and therefore maximum GPE. At the lowest point (B), all GPE has been converted to KE, so KE is maximum.

Section B: Structured Response (20 marks)

11.

(a) 300 J [2]

Working: Work done = Force × distance = 60 N × 5.0 m = 300 J

Marking notes: Award 1 mark for correct formula/substitution. Award 1 mark for correct answer with unit. Common mistake: using the mass (40 kg) instead of the frictional force (60 N).

(b) 30 W [2]

Working: Power = Work done ÷ Time = 300 J ÷ 10 s = 30 W

Marking notes: Award 1 mark for correct formula/substitution. Award 1 mark for correct answer with unit. Accept follow-through from part (a) if the work value was wrong but the method is correct.

12.

(a) 7000 J [2]

Working: GPE = mgh = 70 × 10 × 10 = 7000 J

Marking notes: Award 1 mark for correct substitution. Award 1 mark for correct answer with unit.

(b) Gravitational potential energy is converted to kinetic energy. [1]

Marking notes: Award 1 mark for correct energy conversion statement. Accept "GPE → KE."

(c) 14.1 m/s (or 14 m/s) [3]

Working: Using conservation of energy: GPE at top = KE at bottom mgh = ½mv² 70 × 10 × 10 = ½ × 70 × v² 7000 = 35 × v² v² = 200 v = √200 = 14.14 m/s ≈ 14 m/s

Marking notes: Award 1 mark for stating or using the conservation of energy principle. Award 1 mark for correct substitution. Award 1 mark for correct final answer. Accept 14 m/s or 14.1 m/s. Common mistake: using v = gt without calculating time first, or forgetting to square root.

13.

(a) 1.0 J [2]

Working: GPE = mgh = 0.2 × 10 × 0.5 = 1.0 J

Marking notes: Award 1 mark for correct substitution. Award 1 mark for correct answer with unit.

(b) 0.625 J [2]

Working: KE = ½mv² = ½ × 0.2 × (2.5)² = ½ × 0.2 × 6.25 = 0.625 J

Marking notes: Award 1 mark for correct substitution. Award 1 mark for correct answer with unit. Accept follow-through.

(c) Energy is lost as thermal energy due to friction between the car and the ramp (or energy is lost as sound energy). [1]

Marking notes: Award 1 mark for any valid reason involving energy loss to the surroundings. Accept "friction," "air resistance," "heat," or "sound."

14.

(a) 6000 J [2]

Working: Work done = Force × distance = Weight × height = mgh = 100 × 10 × 6.0 = 6000 J

Marking notes: Award 1 mark for correct substitution. Award 1 mark for correct answer with unit. Common mistake: forgetting to calculate weight first (using 100 N instead of 1000 N).

(b) 400 W [2]

Working: Power = Work done ÷ Time = 6000 J ÷ 15 s = 400 W

Marking notes: Award 1 mark for correct substitution. Award 1 mark for correct answer with unit. Accept follow-through from part (a).

(c) Some energy is wasted as thermal energy due to friction in the motor / Some energy is used to overcome the weight of the cable / Energy is lost as sound. [1]

Marking notes: Award 1 mark for any valid reason. Accept any realistic source of energy loss in a real motor system.

15.

(a) 150 000 J [2]

Working: GPE = mgh = 500 × 10 × 30 = 150 000 J

Marking notes: Award 1 mark for correct substitution. Award 1 mark for correct answer with unit.

(b) Energy cannot be created or destroyed; it can only be converted from one form to another (or transferred from one body to another). [1]

Marking notes: Award 1 mark for a correct statement of the principle. Accept equivalent phrasing.

(c) The total energy of the system is conserved. [1] As the roller coaster moves along the track, kinetic energy and gravitational potential energy are continuously converted from one to the other. However, some energy is converted to thermal energy due to friction between the wheels and the track, and some is used to overcome air resistance. [1] This means the total mechanical energy of the roller coaster gradually decreases, and eventually all the energy is converted to thermal energy, causing the roller coaster to stop.

Marking notes: Award 1 mark for mentioning conservation of energy or that total energy remains constant. Award 1 mark for explaining that energy is converted to thermal energy (or other non-mechanical forms) due to friction/air resistance. Accept any well-reasoned explanation that links energy conversion to the eventual stopping of the roller coaster.

End of Answer Key