CBSE Class 9 Answered

The law of conservation of energy states that the total amount of energy in any isolated system remains constant but cannot be recreated, although it may change forms. The first law of thermodynamics is a statement of the conservation of energy for thermodynamic systems, and is the more encompassing version of the conservation of energy. In short, the law of conservation of energy states that energy can not be created or destroyed, it can only be changed from one form to another. 

 

Thus every other form of energy which we experience or observe is a result of conversion of some other form of energy. These conversions give rise to various types of energies.

 

e.g. The sound energy from a music system is actually due to conversion of electrical energy into sound energy, furthermore, even the electrical energy is the result of conversion of chemical energy (charge) to electrical energy. This explains that although there are different forms of energies, none of them are created, rather they are all the results of energy conversions.