1. Energy =
2. Disambiguation =
3. Citation needed =
4. Electromagnetic =
5. Gravitational =
6. However =
7. Closed systems =
8. Usually macroscopic =
9. Magnetic =
10. System =
11. Generating electric =
12. Such as radiant =
13. Sound energy =
14. Law =
15. Stored =
16. Released =
17. Reservoir =
18. Kinetic =
19. Potential =
20. Mechanical =