As follows from the Law of conservation of energy, any body always has energy. In the presence of motion, this is obvious: there is speed or acceleration, which, multiplied by mass, gives the desired result. However, in the case when the body is motionless, paradoxically, it can also be characterized as having energy.
So, kinetic energy arises when moving, potential - when several bodies interact. If the former is more or less obvious, then often the force that arises between two motionless objects remains beyond comprehension.
It is well known that the planet Earth acts on all bodies located on its surface due to the gravitational field. That is, it attracts any object with a certain force. When moving an object, changing its height, there is also a change in energy indicators. Immediately at the time of lifting, the body has acceleration. However, at its highest point, when an object (even for a split second) is motionless, it has potential energy. The thing is that it is still attracted to it by the field of the Earth, with which the desired body interacts.
In other words, potential energy always arises due to the interaction of several objects that make up the system, regardless of the size of the objects themselves. Moreover, by default, one of them is represented by our planet.
Potential energy - a value depending on the mass of the object and the height by which it is raised. International designation - Latin letters Ep. The potential energy formula is as follows:
Ep = mgh,
Where m is mass, g is gravitational acceleration , h is height.
It is important to consider the height parameter in more detail, since it often becomes a cause of difficulty in solving problems and understanding the value of the quantity in question. The fact is that any vertical movement of the body has its own start and end point. For the correct determination of the potential energy of the interaction of bodies, it is important to know the initial height. If it is not specified, then its value is zero, that is, it coincides with the surface of the Earth. In the case, if both the starting point of reference and the final height are known, it is necessary to find the difference between them. The resulting number will become the desired h.
It is also important to note that the potential energy of the system can have a negative value. Suppose we have already raised the body above the level of the Earth, therefore, it has a height that we will call initial. When you lower it, the formula will look like this:
Ep = mh (h2-h1).
Obviously, h1 is greater than h2, therefore, the value will be negative, which will give the whole formula a minus sign.
It is curious that the potential energy is higher, the farther from the surface of the Earth the body is located. In order to better understand this fact, let us ponder: the higher you need to raise the body above the Earth, the more thoroughly perfect work. The higher the value of the work of any force, the relatively speaking, the more energy is invested. Potential energy, in other words, is the energy of opportunity.
In a similar way, one can measure the interaction energy of bodies when an object is stretched.
Within the framework of the topic under discussion, it is necessary to separately discuss the interaction of a charged particle and an electric field. In such a system, potential charge energy will be present. Consider this fact in more detail. Any charge within the electric field is affected by the force of the same name. Particle movement occurs due to the work produced by this force. Given that the charge itself and the electromagnetic field (more precisely, the body that created it) is a system, we also get the potential energy of charge movement within the given field. Since this type of energy is a special case, it was given the name electrostatic.