O Level Physics Energy Power Quiz

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O-Level Physics Quiz - Energy Power

Name: ______________________
Class: ______________________
Date: ______________________
Score: _______ / 40

Duration: 50 minutes
Total Marks: 40

Instructions:

• Answer all 20 questions.
• Section A: Multiple-choice (1 mark each). Write the letter of the correct option.
• Section B: Structured questions (2–3 marks each). Show your working where calculation is required.
• Section C: Extended response (4 marks each). Explain your reasoning clearly.
• Use $g = 10\ \text{m/s}^2$ where needed.
• This quiz is syllabus-first practice generated from inferred templates; it is not derived from past-year exam papers.

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Section A: Multiple-Choice (Questions 1–5)

1. Which of the following is a correct unit for power?
A. Joule (J)
B. Watt (W)
C. Newton (N)
D. Pascal (Pa)
[____]

2. A lamp transfers $60\ \text{J}$ of energy in $12\ \text{s}$. What is its power?
A. $5\ \text{W}$
B. $720\ \text{W}$
C. $0.2\ \text{W}$
D. $12\ \text{W}$
[____]

3. The efficiency of a device is $0.25$. This means:
A. $25\%$ of input energy is wasted
B. $25\%$ of input energy is useful output
C. $75\%$ of input energy is useful output
D. The device uses $25\ \text{J}$ per second
[____]

4. Which energy store is associated with an object due to its height above the ground?
A. Kinetic
B. Chemical
C. Gravitational potential
D. Elastic
[____]

5. Work done is calculated as:
A. Force ÷ distance
B. Force × distance (in direction of force)
C. Mass × velocity
D. Power × time
[____]

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Section B: Structured Questions (Questions 6–15)

6. A crane lifts a $200\ \text{kg}$ load vertically by $15\ \text{m}$ in $20\ \text{s}$.
(a) Calculate the gain in gravitational potential energy. [2]
(b) Calculate the useful power output of the crane. [1]

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7. A student pushes a box with a force of $50\ \text{N}$ over a distance of $4\ \text{m}$ in the direction of the force. Calculate the work done. [2]

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8. A kettle is rated at $2.0\ \text{kW}$. It takes $100\ \text{s}$ to boil water, using $1.8 \times 10^5\ \text{J}$ of useful energy.
(a) Calculate the total energy supplied by the kettle. [2]
(b) Calculate the efficiency of the kettle as a percentage. [1]

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9. A ball of mass $0.5\ \text{kg}$ is dropped from a height of $8\ \text{m}$. Calculate its kinetic energy just before it hits the ground. (Assume no air resistance.) [2]

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10. A solar panel delivers $300\ \text{W}$ of power. How much energy does it transfer in $2\ \text{hours}$? Give your answer in kJ. [2]

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11. The diagram shows a rollercoaster at two positions.

Image pending generation: diagram for Q11.

Assuming no friction, state the energy transformation from top to bottom and calculate the speed at the bottom. [3]

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12. A car engine produces $40\ \text{kW}$ of useful power and has an efficiency of $20\%$. Calculate the total power input from fuel. [2]

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13. A $1.2\ \text{kW}$ heater runs for $15\ \text{minutes}$. Calculate the energy used in kWh and in J. [2]

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14. Explain why a falling object reaches terminal velocity and what happens to its kinetic energy then. [2]

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15. A battery supplies $120\ \text{J}$ of energy to a motor. The motor lifts a $2\ \text{kg}$ mass by $3\ \text{m}$.
(a) Calculate useful energy output. [1]
(b) Calculate efficiency. [1]

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Section C: Extended Response (Questions 16–20)

16. A hydroelectric dam stores water in a reservoir $50\ \text{m}$ above the turbines. Water of total mass $2.0 \times 10^6\ \text{kg}$ is released.
(a) Calculate the gravitational potential energy stored. [2]
(b) If all this energy is converted to electrical energy at $80\%$ efficiency, calculate the electrical energy output. [1]
(c) If the generation lasts $100\ \text{s}$, calculate the average power output. [1]

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17. Compare renewable and non-renewable energy resources. Use examples and mention one advantage and one disadvantage of each type. [4]

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18. A boy of mass $50\ \text{kg}$ runs up a staircase of height $5\ \text{m}$ in $10\ \text{s}$.
(a) Calculate his power output. [2]
(b) State one assumption made and how it affects the result if wrong. [2]

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19. Describe an experiment to determine the efficiency of a small electric motor lifting a load. Include measurements and calculations. [4]

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20. The figure shows a pendulum.

Image pending generation: diagram for Q20.

(a) State the energy change from highest to lowest point. [1]
(b) Calculate speed at lowest point. [2]
(c) Explain why the pendulum eventually stops. [1]

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O-Level Physics Quiz - Energy Power (Answer Key)

Total Marks: 40
Note: Syllabus-first practice from inferred templates; not past-year derived.

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Section A (1 mark each)

1. B
Power is defined as rate of energy transfer; unit is Watt (W). J is energy, N is force, Pa is pressure.

2. A
$P = E/t = 60/12 = 5\ \text{W}$.

3. B
Efficiency = useful output / total input = 0.25 = 25% useful.

4. C
Gravitational potential energy depends on height.

5. B
Work = Force × distance (in direction of force).

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Section B (marks as indicated)

6. [3 marks]
(a) $E_p = mgh = 200 \times 10 \times 15 = 30\,000\ \text{J}$ (2 marks: 1 for formula, 1 for value)
(b) $P = E/t = 30\,000 / 20 = 1500\ \text{W}$ (1 mark)

7. [2 marks]
$W = Fd = 50 \times 4 = 200\ \text{J}$ (1 for formula, 1 for answer)

8. [3 marks]
(a) Total energy = $P \times t = 2000 \times 100 = 2.0 \times 10^5\ \text{J}$ (2 marks)
(b) Efficiency = $(1.8 \times 10^5) / (2.0 \times 10^5) \times 100 = 90\%$ (1 mark)

9. [2 marks]
By conservation, $E_k = E_p = mgh = 0.5 \times 10 \times 8 = 40\ \text{J}$ (1 formula, 1 answer)

10. [2 marks]
$E = Pt = 300 \times (2 \times 3600) = 2\,160\,000\ \text{J} = 2160\ \text{kJ}$ (1 for conversion, 1 for answer)

11. [3 marks]
Transformation: GPE → KE (1 mark).
$mgh = \frac{1}{2}mv^2 \Rightarrow v = \sqrt{2gh} = \sqrt{2 \times 10 \times 20} = 20\ \text{m/s}$ (2 marks)

12. [2 marks]
Efficiency = useful / total → total = $40\,000 / 0.20 = 200\,000\ \text{W} = 200\ \text{kW}$ (1 formula, 1 answer)

13. [2 marks]
$t = 15\ \text{min} = 0.25\ \text{h}$; $E = 1.2 \times 0.25 = 0.30\ \text{kWh}$;
$J = 1.2 \times 10^3 \times 15 \times 60 = 1.08 \times 10^6\ \text{J}$ (1 each)

14. [2 marks]
Air resistance increases with speed; at terminal velocity resultant force zero, constant speed (1). KE constant as speed constant (1).

15. [2 marks]
(a) $E_p = mgh = 2 \times 10 \times 3 = 60\ \text{J}$ (1)
(b) Eff = $60/120 = 0.5 = 50\%$ (1)

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Section C (4 marks each)

16. [4 marks]
(a) $E_p = mgh = 2.0 \times 10^6 \times 10 \times 50 = 1.0 \times 10^9\ \text{J}$ (2)
(b) Electrical = $0.8 \times 1.0 \times 10^9 = 8.0 \times 10^8\ \text{J}$ (1)
(c) $P = E/t = 8.0 \times 10^8 / 100 = 8.0 \times 10^6\ \text{W}$ (1)

17. [4 marks]
Renewable: solar/wind (example 1). Advantage: sustainable (1). Disadvantage: intermittent (1).
Non-renewable: coal/oil (example 1). Advantage: high energy density (1). Disadvantage: pollution (1).

18. [4 marks]
(a) $E_p = 50 \times 10 \times 5 = 2500\ \text{J}$; $P = 2500/10 = 250\ \text{W}$ (2)
(b) Assumption: no energy loss to friction/air (1); if wrong, actual power higher (1).

19. [4 marks]
Measure mass, height, time, voltage, current (1). Useful = mgh (1). Input = VI t (1). Eff = mgh/(VI t) (1).

20. [4 marks]
(a) GPE → KE (1)
(b) $v = \sqrt{2gh} = \sqrt{2 \times 10 \times 0.3} = \sqrt{6} \approx 2.45\ \text{m/s}$ (2)
(c) Air resistance dissipates energy as heat (1)