Question

State the law of the conservation of mechanical energy​

Answer 1

The law of the conservation of mechanical energy states that the total mechanical energy of an isolated system remains constant, unless external forces are present. This means that the sum of the kinetic energy and potential energy within the system will remain constant over time, unless the system is subjected to external forces such as friction or gravity. This law is based on the principle that energy cannot be created or destroyed, but rather it can only be transferred or transformed. Therefore, any changes in the mechanical energy of a system must be due to the transfer or transformation of energy from one form to another, rather than the creation or destruction of energy itself.

Answer 2

The law of the conservation of mechanical energy states that the total mechanical energy of a closed system remains constant, unless there is work done by non-conservative forces or heat transfer to or from the system.

In other words, the law states that the sum of the kinetic energy (energy of motion) and potential energy (energy due to position) of a system remains constant as long as there are no non-conservative forces acting on the system. Non-conservative forces are forces that dissipate energy, such as friction and air resistance. If these forces are present, they will convert some of the mechanical energy of the system into other forms of energy, such as heat or sound.

For example, if you lift a book off the ground, you are doing work on the book, which increases its potential energy. At the same time, the kinetic energy of the book decreases, because it is not moving. If you then release the book, it will fall to the ground, converting its potential energy back into kinetic energy. If there are no non-conservative forces present, the sum of the kinetic energy and potential energy of the book will remain constant throughout this process. This is an example of the conservation of mechanical energy in action.