The word "energy" comes from the Greek language and has the meaning "action", "activity". The very concept was first introduced by the English physicist T. Jung in the early 19th century. By "energy" is meant the ability of a body that has this property to do work. The body is capable of doing more work, the more energy it has. There are several of its types: internal, electrical, nuclear and mechanical energy. The latter is more common in our everyday life. Man has long since learned to adapt it to his needs, transforming into mechanical work with the help of various adaptations and designs. We can also transform certain types of energy into others.
Within the framework of mechanics (one of the sections of physics), mechanical energy is a physical quantity that characterizes the ability of a system (body) to perform mechanical work. Consequently, the indicator of the presence of this type of energy is the presence of a certain speed of motion of the body, which, having it, it can do the work.
Types of mechanical energy: kinetic and potential. In each case, the kinetic energy is a scalar quantity that is composed of the sum of the kinetic energies of all the material points that make up a particular system. Whereas the potential energy of a single body (a system of bodies) depends on the mutual position of its (their) parts within the framework of an external force field. The indicator of the change in potential energy is perfect work.
The body has kinetic energy if it is in motion (otherwise it can be called energy of motion), and potential - if it is raised above the surface of the earth at some height (this is the energy of interaction). Measures mechanical energy (as well as other species) in Joules (J).
To find the energy that the body possesses, one must find the work required to transfer this body to the present state from the state of zero (when the energy of the body is equated to zero). Below are the formulas according to which mechanical energy and its types can be determined:
- kinetic - Ek = mV 2/2;
- potential - Ep = mgh.
In the formulas: m is the mass of the body, V is the speed of its translational motion, g is the acceleration of the fall, h is the height at which the body is raised above the ground.
The finding for the system of bodies of total mechanical energy consists in revealing the sum of its potential and kinetic components.
Today, very often the mechanical operation of systems (for example, the energy of a rotating shaft) is subject to a subsequent transformation in the production of electrical energy, for which the current generators are used. A lot of devices (engines) have been developed capable of performing a continuous transformation into the mechanical energy of the working medium's potential.
There is a physical law of conservation of it, according to which in a closed system of bodies, where there is no action of frictional and resistive forces, the constant is the sum of both its forms (Ek and Ep) of all its constituent bodies. Such a system is ideal, but in reality such conditions can not be achieved.