Level: JHS, Basic 8 | Subject: Integrated Science | Strand: Forces and Energy | Topic: Energy (Work, Energy and Power)
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 SI unit of work is the
2. Work done is calculated as
3. A force of 20 N moves a box through 5 m. The work done is
4. A porter does 240 J of work moving a load through 8 m. The force used is
5. A boy pushes a heavy wall for some minutes but the wall does not move. The work done is
6. The unit of power is the
7. Power is defined as
8. A girl does 600 J of work in 20 s. Her power is
9. A pump of power 500 W runs for 40 s. The work done is
10. 1 kilowatt is equal to
11. Energy is best described as
12. The energy of a moving object is
13. A stretched rubber band has
14. A 2 kg coconut is on a tree 5 m above the ground. Take g = 10 N/kg. Its potential energy is
15. A ball of mass 0.5 kg moves at 4 m/s. Its kinetic energy is
16. In an electric fan, the main energy change is
17. A solar panel changes
18. When a mango falls from a tree, its
19. The law of conservation of energy states that energy
20. A machine of power 100 W does 3000 J of work. The time taken is
Essay Questions
- (a) What is work in science? (b) State the SI unit of work. (c) A force of 40 N moves an object through 6 m. Calculate the work done. (5 marks)
- (a) Define power. (b) State its SI unit. (c) A machine does 1500 J of work in 30 s. Calculate its power. (5 marks)
- State the main energy change in each of the following: (a) an electric bulb (b) a solar panel (c) a charcoal stove (d) a falling mango. (4 marks)
- State the law of conservation of energy and give one example from daily life. (3 marks)
- A stone of mass 3 kg is lifted to a height of 4 m. Take g = 10 N/kg. Calculate its potential energy. State the energy change when the stone is released. (4 marks)
Essay Questions: Marking Guide for Teachers and Parents
- (a) Work is done when a force moves an object in the direction of the force (1). (b) Joule (1). (c) W = F x d (1); W = 40 x 6 (1); W = 240 J (1).
- (a) Power is the rate of doing work, or work done per second (1). (b) Watt (1). (c) P = W / t (1); P = 1500 / 30 (1); P = 50 W (1).
- (a) Electrical to light and heat (1). (b) Light to electrical (1). (c) Chemical to heat and light (1). (d) Potential to kinetic (1).
- Energy cannot be created or destroyed (1) but can only change from one form to another (1). Example: electrical energy changes to light and heat in a bulb, or potential to kinetic in a falling fruit (1).
- PE = m x g x h (1); PE = 3 x 10 x 4 (1); PE = 120 J (1). When released, potential energy changes to kinetic energy (1).
Education Always (education.inspiringalways.com). Original practice questions, not official WAEC or BECE questions.
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