الشغل والطاقة - الميكانيك .. الفيزياء

Work and Energy - Mechanics .. Physics

Work and Energy

The words work and energy are used loosely in everyday life. In the field of physics, however, they have a very precise meaning. In the picture, the man appears to be doing a large amount of work. But in reality, in the physical sense of the word, he is not doing any work until the rock starts moving. In physics, the "work" done is equal to the product of the force F and the distance F that the body travels in the direction of the same force: F = F × F. Work is measured in units of joules if the force and distance are measured in units of newtons and meters (the joule is the unit of work in the International System of Measures and is equal to the newton meter).

As for the word "energy", its meaning was not determined until the nineteenth century. Today, it is considered one of the main concepts in physics. It means, quite simply, the ability of a body to accomplish a certain amount of work (in the physical sense of the word, of course).

In order for the man to move the rock towards the edge of the abyss (which is a distance F away from him), he must do work equal to Q × F. Then, the rock becomes able to accomplish work on its own because it has a certain energy. But this energy remains latent in it as long as it remains fixed in place without moving. It is worth noting that the latent energy in the rock is the amount of work it can accomplish if it falls from the highest possible height under the influence of the Earth's gravity, and its value is equal to the product of the weight of the rock in kg by the height m that separates the edge from the bottom of the abyss.

The man's fatigue is not in vain as a result of pushing the rock from this science, because when it falls a distance of 30% of its total height, it loses 30% of its latent energy, and this amount of energy has not disappeared, of course, because energy does not disappear at all, but rather is transformed into movement, or specifically, into kinetic energy. It must be noted that the kinetic energy of an object is directly proportional to the square of its speed.

After the body falls 30% of its full height, the equation becomes: K v2 / 2 = 3.0 kg m, and its speed becomes the square root of 0.6 g m, which is a value independent of the mass. This equation can only be used in a vacuum. As for in the air, it is known that the speed of a feather falling is less than the speed of a stone falling due to the difference in air resistance for each of these two bodies. It is noticeable in the picture below that the kinetic energy and potential energy in the rock were eliminated when it reached the bottom of the abyss. This is because all of its energy was used to dig a hole in the ground, heat the air and soil around it, and fill the atmosphere around it with some noise and commotion. It must be noted here that energy is transformed from one form to another, and that it is not created from nothing, nor is it ever destroyed - this is the principle of conservation of energy. However, Einstein discovered the possibility of converting mass into energy, and vice versa, according to his famous equation F = m × h2 (h represents the speed of light). The principle of conservation of energy became applicable only to bodies whose mass does not change.

Work, potential energy, and kinetic energy.