The law of conservation of energy states that energy
- A. can be created when needed
- B. can be destroyed by friction
- C. can be transformed from one form to another but the total remains constant
- D. always increases in an isolated system
Explanation
Friction does not destroy energy; it converts organised kinetic energy into disordered thermal energy, which is harder to use but is still energy. Every apparent loss in mechanics is a transfer to a form outside the system being considered. Including mass as a form of energy through E equals mc squared makes the law hold in nuclear reactions too.