# Law of Conservation of Energy, Definition of the Law of Conservation of Energy (For CBSE, ICSE, IAS, NET, NRA 2022)

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# Law of Conservation of Energy

• The law states that energy can neither be created nor destroyed - only converted from one form of energy to another.
• It means that a system always has the same amount of energy, unless it՚s added from the outside.
• This is particularly confusing in the case of non-conservative forces, where energy is converted from mechanical energy into thermal energy, but the overall energy does remain the same.
• The only way to use energy is to transform energy from one form to another.

## Details

• Conservation of energy, principle of physics according to which the energy of interacting bodies or particles in a closed system remains constant.
• The first kind of energy to be recognized was kinetic energy, or energy of motion.
• In certain particle collisions, called elastic, the sum of the kinetic energy of the particles before collision is equal to the sum of the kinetic energy of the particles after collision.
• The notion of energy was progressively widened to include other forms
• Energy is required for the evolution of life forms on earth. In Physics, it is defined as the capacity to do work.
• Energy exists in different forms in nature. You have learned about various forms of energy – heat, electrical, chemical, nuclear etc.
• This law is known as the law of conservation of energy.

## Definition of the Law of Conservation of Energy

• The law of conservation of energy states that
• “Energy can neither be created nor be destroyed, it can be transformed from one form to another”
• By taking all forms of energy into account, the total energy of an isolated system always remains constant.
• All the forms of energy follow the law of conservation of energy. In brief, the law of conservation of energy states that
• In a closed system, i.e.. , a system that is isolated from its surroundings, the total energy of the system is conserved.
• This law means that a system always has the same amount of energy, unless it՚s added from the outside.
• This is confusing in the case of non-conservative forces, where energy is converted from mechanical energy into thermal energy, but the overall energy does remain the same.

### Energy Transformation

• To use energy is to transform energy from one form to another, the only way.
• The amount of energy in any system is determined by the following equation:

• = the total internal energy of a system.
• = the initial internal energy of a system.
• W = the work done by or on the system.
• Q = the heat added to, or removed from, the system.

To determine the change in internal energy of the system using the equation:

• This is a statement of the first law of thermodynamics.
• In the 20th century, Einstein figured out that even mass is a form of energy.
• The amount of mass directly relates to the amount of energy, as determined by the most famous formula in physics:

• E = the amount of energy in an object or system.
• m = the mass of the object or system.
• C = the speed of light, roughly

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