The word "energy" comes from the Greek language and means "action", "activity". The concept itself was first introduced by the English physicist T. Jung at the beginning of the 19th century. By "energy" is meant the ability of a body possessing this property to do work. The body is able to do the more work, the more energy it has. There are several types of it: internal, electrical, nuclear and mechanical energy. The latter is more common than others in our daily life. Since ancient times, man has learned to adapt it to his needs, converting it into mechanical work using a variety of devices and structures. We can also transform one form of energy into another.
In the framework of mechanics (one of the branches of physics), mechanical energy is a physical quantity that characterizes the ability of a system (body) to perform mechanical work. Therefore, an indicator of the presence of this type of energy is the presence of a certain speed of the body, having which, it can do work.
Types of mechanical energy: kinetic and potential. In each case, kinetic energy is a scalar quantity,consisting of the sum of the kinetic energies of all material points that make up a particular system. While the potential energy of a single body (system of bodies) depends on the relative position of its (their) parts within the external force field. The indicator of change in potential energy is the perfect work.
A body has kinetic energy if it is in motion (otherwise it can be called the energy of motion), and potential energy if it is raised above the earth's surface to some height (this is the energy of interaction). Mechanical energy is measured (like other types) in Joules (J).
To find the energy that a body has, you need to find the work spent on transferring this body to its current state from the zero state (when the body's energy is equal to zero). The following are formulas according to which mechanical energy and its types can be determined:
– kinetic – Ek=mV2/2;
– potential – Ep=mgh.
In the formulas: m is the mass of the body, V is the speed of its forward movement, g is the acceleration of the fall, h is the height to which the body is raised above the earth's surface.
Finding the total mechanical energy for a system of bodies is to identify the sum of its potential and kinetic components.
Examples of how mechanical energy can be used by man are the tools invented in ancient times (knife, spear, etc.), and the most modern watches, aircraft, etc.mechanisms. The forces of nature (wind, sea tides, river flow) and the physical efforts of a person or animals can act as sources of this type of energy and the work performed by it.
Today, very often the mechanical work of systems (for example, the energy of a rotating shaft) is subject to subsequent conversion in the production of electrical energy, for which current generators are used. Many devices (motors) have been developed that are capable of continuously converting the potential of the working fluid into mechanical energy.
There is a physical law of its conservation, according to which in a closed system of bodies, where there is no action of friction and resistance forces, the constant value will be the sum of both types of it (Ek and Ep) of all its constituent bodies. Such a system is ideal, but in reality such conditions cannot be achieved.
