In schools, wise teachers tell their students that there is a conservation law in mechanics. Its meaning is that energy in a closed system cannot disappear irretrievably, wasting on the performance of any work. In such processes, there is not a disappearance, but a transformation of the energy of one kind into another. For example: clicking the switch - and the light bulb flashes brightly. The meter regularly calculates the watts of energy expended. Where does she go? It's simple: an electric current does the work, while the energy is converted into radiation and heat. In other words, conservation laws in mechanics are relevant for any mechanical device (or even electrical - the difference is only in the variety of the initial energy and the name of the same phenomenon). In fact, the law of conservation is a fundamental principle in accordance with which the whole universe lives.
First of all, it is necessary to determine what kinetic and potential energy are. In simple terms, the first is the energy of body movement that characterizes the work performed by the body. And the second is the temporarily unrealized energy of the system of bodies, determined by the nature of the interaction and the location of objects in the system itself. It is only natural that the term comes from a Latin word meaning "opportunity." In mechanics, these two varieties of energy are converted one into the other.
Conservation laws in mechanics work as follows. For example, an object thrown up at the moment of receipt of the impulse has a maximum value of kinetic energy. Accordingly, its speed is the highest at the initial moment. Gradually, it decreases, since kinetic energy is converted into potential energy . As a result, the item slows down and stops. This means that his entire supply of the initial energy of the pulse was converted into potential and accumulated in the system. Further, due to the gravitational effect, the object begins to fall. Potential energy is converted back to kinetic. It is easy to guess that at the initial moment of movement the speed is minimal, but gradually increases, since the value of the kinetic energy of the system increases. It should be noted that in this case, despite the influence of the Earth's magnetic field (additional impulse), the total sum of the energies of the system remains unchanged.
To better understand the conservation laws in mechanics, it makes sense to turn to your own life experience. Surely, in childhood, everyone dropped a small but massive ball or ordinary ball onto a metal base. At the same time, he jumped up and fell again. This was repeated until the movement spontaneously ceased. But what about the law of conservation of energy in mechanics? Indeed, logically, the potential energy of a falling ball should be fully converted into kinetic, and vice versa. Almost a perpetual motion machine. Are conservation laws in mechanics really not fulfilled in this case? In fact, in this situation, the system is affected by friction against air molecules and internal deformations of the surface and the ball. It is they who “steal” their part of the energy, which is why the ball gradually stops bouncing (by the way, therefore, it is impossible to create a perpetual motion machine in the framework of classical mechanics).
The universality of conservation laws allows us to use them not only in calculating the interaction of the systems of the macrocosm, but also, partially, in the microcosm. Neither the trajectory of movement, nor the type of forces acting on the system affects the result - conservation laws work!