Eternity means unchanging. So, the law of conservation of energy is a law which states that energy is conserved and cannot change (magnitude) over time, having the same value both before something happens and after it. Energy can be changed in form, but the magnitude will always be the same.
The most common definition of energy is work that can be done by a certain force (gravity, electromagnetic, etc.). In the Big Indonesian Dictionary (KBBI), in the field of physics, energy is the ability to do work (eg for electrical and mechanical energy).
Energy here is the total energy of a system. The total energy of a system can be in the form of kinetic energy, potential energy, heat energy, and so on. These forms of energy can be transformed into other forms of energy so that the total energy in a system will always be the same.
Basic Concepts of the Law of Conservation of Energy
“The Law of Conservation of Energy states that energy can neither be created nor destroyed, but can only change from one form to another.” This principle is known as the conservation of energy or the first law of thermodynamics.
Based on this concept, we can know that energy is never destroyed, therefore the amount of energy will always be the same but the amount can be separated and converted into other forms of energy.
There are many types of energy, in addition to potential energy and kinetic energy in ordinary objects (macroscopic scale), there are also other forms of energy, such as electrical energy, thermal energy, nuclear energy and chemical energy stored in food and fuel. Nuclear energy emerged after the atomic theory which said that other forms of energy (electrical energy, chemical energy, etc.) were kinetic energy, while at the atomic level (microscopic scale) it was referred to as potential energy.
Energy in the universe is constant, so it is called the conservation of energy. All existing energy cannot be destroyed and can only be converted into other forms of energy. Energy is divided into several forms, namely the form of kinetic energy, potential energy, and other forms of energy.
Benefits of the Law of Conservation of Energy
The law of conservation of energy in the field of physics is a theoretical basis that can be applied in almost all scientific disciplines. In addition, by understanding and understanding the concept of the law of conservation of energy, the benefits gained can be applied in our daily lives.
Every existing energy can be used by humans to help them in their daily lives. Thus, it becomes easier for humans to do various things in their daily lives thanks to the energy that can be utilized.
An example of the application of the law of conservation of energy is the change of electrical energy into heat energy (iron), electrical energy into motion energy (fan) etc. The process of changing the form of this energy is actually caused by a change in energy between potential energy and kinetic energy at the atomic level. At the macroscopic level, we can also find so many examples of energy changes.
The Law of Conservation of Energy Formula
If the law of conservation of mechanical energy applies in a system, then the mechanical energy of the system will always remain. In other words, the sum of the potential energy and kinetic energy of the system is the same at all points so that the amount of mechanical energy in a moving object is always constant. Mathematically formulated as follows:
Em1, Em2 : initial mechanical energy and final mechanical energy (J).
Ek1, Ek2: initial kinetic energy and final kinetic energy (J).
Ep1, Ep2: initial potential energy and final potential energy (J).
In the International System of Units or SI (International System of Units), the unit of energy is the joule. One joule is equal to the work done by Newton’s force acting at a distance of one meter. Whereas in space, energy has no direction and is therefore considered a scalar quantity.
Based on the law of conservation of energy, energy is divided into 3 main forms of energy, namely:
Kinetic energy is the work required to move an object with a certain mass from rest to a certain speed. So, Kinetic Energy is the energy that an object has due to its motion. The word “kinetic” itself comes from the Greek, namely “kinesis” which means motion. In general, there are two types of kinetic energy, namely:
- Translational Kinetic Energy, which is the energy possessed by an object undergoing straight motion (its trajectory is a straight line).
- Rotational Kinetic Energy, which is the energy possessed by a rotating object (its path is a circle).
Ek = Kinetic Energy
m = Mass of Object (kg)
v = Object’s Velocity (m/s)
Potential energy is the energy possessed by an object due to the position (height) of the object. There are several things that affect the potential energy of an object, but the three most important are the object’s mass, the force of gravity and the object’s height.
Ep= Potential Energy
m = Mass of Object (kg)
g = Gravity (m/s)
h = Altitude (m)
Mechanical energy is energy associated with the motion and position of an object. Therefore, mechanical energy is energy obtained from the sum of kinetic energy and potential energy in doing work.
An example of mechanical energy is when we hit a nail with a hammer, we will lift the hammer so that it is in a higher position (potential energy), then we move towards the nail with a certain speed (kinetic energy), then when the nail and hammer touch, the nail will driven (mechanical energy) and our goal is achieved.
Em = Mechanical Energy
Ek = Kinetic Energy
Ep = Potential Energy
In physics and chemistry, the law of conservation of energy states that the total energy of an isolated system remains constant; it is said to be preserved over time. This law, first proposed and tested by milie du Châtelet, means that energy can neither be created nor destroyed; instead, it can only be changed or transferred from one form to another. For example, chemical energy is converted into kinetic energy when a piece of dynamite explodes. If one added up all the forms of energy released in an explosion, such as the kinetic energy and potential energy of the pieces, as well as heat and sound, one would obtain an exact derivation of the chemical energy in the combustion of dynamite.
Classically, the conservation of energy is different from the conservation of mass; However, special relativity shows that mass is related to energy and vice versa with E = mc2, and science now holds that mass-energy as a whole is conserved. Theoretically, this implies that any object of mass can be transformed into pure energy by itself, and vice versa, although it is believed to be possible only under the most extreme physical conditions, such as those that might have existed in the universe shortly after the Big Bang. or when a black hole emits Hawking radiation.
The consequence of the law of conservation of energy is that a perpetual motion machine of the first kind cannot exist, in other words, no system without an external energy supply can transmit an infinite amount of energy around it. For systems that do not have translational symmetry of time, it may not be possible to define conservation of energy. Examples include curved space motion in general relativity or time crystals in condensed matter physics.
Source : Wikipedia
Application of the Law of Conservation of Energy
In hydro power plant dams, water is dammed to a high height (h) so that the water in the reservoir has high potential energy. Water enters from the sluice gate through the waterway to the turbine and rotates the turbine. The potential energy of the water then turns into kinetic energy in the turbine so that the turbine rotates. Because the turbine rotates, the generator also rotates. The kinetic energy in the turbine is then converted into electrical energy in the generator. Electricity from the generator is then routed through long-distance high-voltage cables. Electrical energy is what we enjoy everyday.
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