Level: JHS, Basic 8 | Subject: Integrated Science | Strand: Forces and Energy | Topic: Conservation of Energy
Read the summary notes first, then try these questions. Go back to the summary notes for this topic.
Part A has 20 tick-box questions. Part B has 5 essay questions with a marking guide at the bottom.
Test Yourself: 20 Objective Questions
Tick one answer for each question, then press Review answer. If your answer is wrong, it will be marked first, then the correct answer will show in green.
1. The law of conservation of energy says that energy
2. The SI unit of energy is the
3. In an electric bulb, the main energy change is
4. A solar panel changes
5. A dry cell torch changes
6. A mango falling from a tree changes
7. A 2 kg mango is 5 m above the ground. Take g = 10 N/kg. Its potential energy is
8. The mango in the question above hits the ground. Ignoring air resistance, its kinetic energy just before landing is
9. At the highest point of a swinging pendulum, the energy is mainly
10. At the lowest point of a swinging pendulum, the energy is mainly
11. A pendulum slowly stops swinging because some energy changes to
12. A machine takes in 200 J and gives out 50 J of useful energy. Its efficiency is
13. The wasted energy in most machines is usually
14. Which one is a renewable source of energy?
15. Which one is a fossil fuel?
16. In a hydroelectric dam like Akosombo, the energy changes are
17. A plant making food changes
18. Which is a good way to save electricity at school?
19. A challenge of solar power in Ghana is that
20. When we say energy is 'used up', the energy has really
Essay Questions
- State the law of conservation of energy. Give one example from daily life. (3 marks)
- State the main energy change in each of the following: (a) an electric fan (b) a radio (c) a charcoal stove (d) a solar panel. (4 marks)
- A 4 kg stone is lifted to a height of 3 m. Take g = 10 N/kg. (a) Calculate its potential energy. (b) State its kinetic energy just before it lands if it is dropped. (5 marks)
- A machine takes in 500 J of energy and gives out 400 J as useful work. (a) Calculate its efficiency. (b) What happens to the remaining energy? (4 marks)
- Give two advantages and two challenges of using solar energy in Ghana. (4 marks)
Essay Questions: Marking Guide for Teachers and Parents
- Energy cannot be created or destroyed (1) but changes from one form to another (1). Example: electrical energy changes to light and heat in a bulb (1).
- (a) Electrical to kinetic (1). (b) Electrical to sound (1). (c) Chemical to heat and light (1). (d) Light to electrical (1).
- (a) PE = m x g x h (1); PE = 4 x 10 x 3 (1); PE = 120 J (1). (b) KE = 120 J (2).
- (a) Efficiency = useful output / total input x 100 (1); 400 / 500 x 100 (1); 80% (1). (b) It is changed to wasted heat (and sound) (1).
- Any two advantages (1 mark each): clean energy, no air pollution, lower carbon emissions, free sunshine, can be used in rural areas. Any two challenges (1 mark each): high cost at the start, no power at night, needs batteries, cloudy days reduce output.
Education Always (education.inspiringalways.com). Original practice questions, not official WAEC or BECE questions.