The law of conservation of energy states that in an isolated system the total energy remains constant—it is said to be conserved over time. Energy can neither be created nor be destroyed, but it can change from one form to another form. for instance,
1. Mechanical energy, such as the kinetic energy of motion, can be converted to heat energy
eg. in the heating of a car’s brakes when it slows down. Chemical energy in the gasoline of the car can be converted into both heat energy in the exhaust and heating the engine, and into mechanical energy to move the car.
2.Potential energy such as the gravitational potential energy stored in an object which is on a high shelf, can be converted into kinetic energy as the object falls down.
3.Electrical energy can be converted to heat or mechanical energy or sound energy in a variety of useful ways around the house using common appliances.
From these examples it is evident that energy can neither be created nor destroyed it can only be changed from one form to another desired form.
No, energy cannot be created or destroyed. This is known by the law of conservation of energy which states that the total energy of an isolated system remains constant over time, i.e. energy is conserved.
Energy can be converted from one form into another, e.g. from chemical to heat to kinetic in a combustion engine, or from kinetic to electrical in an electric generator. Also, we know that mass and energy are two forms of the same thing from Einstein's equation `E=mc^2.` This fact is applied in nuclear power plants and nuclear weapons which turn mass into energy (mainly heat) by using nuclear fission or fusion.
If you want to know more on the topic I suggest you read History and root of the principle of the conservation of energy.
As the well known saying goes, energy can not be created or destroyed, only changed. This is demonstrated by the law of conservation, and it is why perpetual-motion machines are impossible.
Think about one of those 'impossible waterfalls' for a second. They are impossible for a simple reason: They can not create energy for themselves. When the water falls down from gravity, it will not have enough energy to move back up, because the force required to push the water back up is larger than the force of gravity acting on the water and would therefore require extra energy. Without adding in extra energy sources, no system can run perpetually.