Work and Energy — Advanced

Grade 9 Science — Work and Energy — Advanced: 25 practice questions with instant scoring and explanations.

1. Power is defined as:
2. If 500 J of work is done in 10 seconds, what is the power?
3. The SI unit of power is:
4. A bulb rated at 60 W means:
5. The commercial unit of electrical energy is:
6. How many joules are equal to 1 kWh?
7. If an electrical device uses 2 kW of power and operates for 3 hours, the energy consumed is:
8. The law of conservation of energy states that:
9. In a pendulum, what happens as it swings?
10. An example of energy transformation is:
11. In an ideal (frictionless) system, if an object falls from height h, its velocity when reaching the ground is found using:
12. An electric motor converts:
13. A device that converts chemical energy to electrical energy is a:
14. If a machine consumes 5000 J of energy and does 4000 J of useful work, its efficiency is:
15. The reason energy is 'lost' in mechanical systems is due to:
16. A 40 W lamp operated for 5 hours consumes energy equal to:
17. In a hydroelectric power plant, which energy transformation occurs?
18. A car accelerating from rest to 20 m/s requires work. This work is converted to:
19. If an electric heater rated 2000 W operates for 2 hours, the energy consumed in kWh is:
20. The efficiency of a system is always:
21. A body is projected vertically upward. At what point is its kinetic energy minimum?
22. An object at height h and moving with velocity v has total mechanical energy of:
23. In an internal combustion engine, chemical energy is converted to:
24. If power P is constant and time t increases, the work done will:
25. The energy stored in a compressed spring is called: