Conservation Laws


Conservation laws balances the universe in a very good manner. A given physical property doesn't often alter with time in an enclosed physical system, according to the conservation law which governs it. Certain sets of principles regulate energy, momentum, angular momentum, mass, and electric charge throughout classical physics.

Additional conservation norms in particle physics implement subatomic particle properties that remain constant throughout interactions. The ability to forecast a system's macroscopic behaviour without thinking about the microscopic specifics of how a physical process or chemical reaction would unfold is a key function of conservation laws.

What are the Conservation Laws?

Conservation laws are regarded as fundamental natural rules that have wide applications in the domains of physics as well as other fields. Because they define which natural processes can and cannot happen, conservation laws are essential to our comprehension of the physical universe. As an illustration, the conservation law of energy states that while the type of energy may change, its overall quantity does not. Physical processes generally do not modify the overall quantity of the property covered by that law. The majority of conservation rules are precise, or absolute, in that they hold true for all conceivable processes.

What is the type of Conservation Law?

There are several conservation laws that can be classified into exact and approximate laws. Some of the basic and important laws of conservation are the following −

Conservation of Energy

In accordance with the law of conservation of energy, generally known as the first law of thermodynamics, the total quantity of energy contained within the system must remain constant. There is no such thing as energy, and it cannot be created or simply disappear. However, energy can change from one form to another, but it can be dispersed as work, potential energy, or kinetic energy. Heat is generated by the kinetic energy of molecules and atoms.

We may solve numerous dynamics-related issues with the help of the law of conservation of energy, which also serves as the foundation for the study of thermodynamics.

$$\mathrm{Total\:Energy\:of\:system = U}$$


Conservation of Mass

The Law of Conservation of Mass was formulated in Year 1789 after Antoine Lavoisier realised that mass is neither generated nor destroyed during physical and chemical processes. The mass of any specific element at the beginning of a reaction will, therefore, always be equivalent to that element's mass at the end of the reaction. If we include all reactants and products in a chemical process, the total mass will remain constant over time in any closed system. The discovery made by Lavoisier revolutionised science and laid the groundwork for modern chemistry.

Conservation of Charge

In accordance with the law of conservation of charge, the overall charge of a closed system will never change. This indicates that no system will ever have a different total charge between any two moments if it is not sending and receiving matter or energy from its surroundings. The object with the surplus electrons will be negatively charged, and the object with the reduced quantity of electrons will carry a positive charge of equal magnitude if two particles in an isolated system with net charges of zero exchange one million electrons with one another. The system's overall charge has not changed and will never change.

Conservation of Momentum

The total momentum of an isolated system will remain unaffected in the absence of any external force, according to the concept of conservation of momentum. In other words, momentum can only be altered by the action of forces, which are encapsulated by Newton's equations of motion. Momentum cannot be generated or destroyed. The product of an object's mass and speed is momentum, which is also the same as the total force required to bring an object to rest.


Problems involving collisions when the momentum is preserved, and the net external force is zero are one application of the conservation of momentum in the real world.

Conservation of Angular Momentum

According to the law of conservation of angular momentum, an isolated system's total angular momentum is preserved or stays constant in magnitude and direction in the absence of external torque.

The law of conservation of angular momentum dictates that −


If $\mathrm{\omega_1}$ is the angular velocity whereas the moment of inertia is $\mathrm{I_1}$ and $\mathrm{\omega_2}$ is the angular velocity while the moment of inertia is $\mathrm{I_2}$.

What are the characteristics of conservation Laws?

There are some important and unique characteristics of Conservation laws, such that

Homogeneity of Time

If we conduct an experiment at a certain location today and repeat it one year later at the same location, we get the exact same findings

Homogeneity of Space

There is no preferred position in the universe because the laws of nature assume the same shape everywhere.

Isotropy of Space

The laws of conservation are not exact for a particular direction, but it is the same for every direction in the universe.


As we have studied in the above paragraphs, the actual identification or feasibility of any action in the universe can be predicated on the behalf of these laws of conservation. The stability of a reaction in chemistry and biology only depends on the conservation of charge, mass, and energy. Moreover, in the physical world, all types of motion are governed by the law of conservation of momentum. Also, these laws of conservation are not valid for specific points, places, times, and directions while in-universe these are the same for every point.


Q1. What are the approximate conservation laws?

Ans. The conservation laws which are not so exact at all points, however, have some limitations. The approximate laws are valid under specific conditions, such as the body in slow motion, the microscopic unit of time, etc.

Q2. What are the applications of Conservation laws?

Ans. There are several applications of laws of conservation in our daily life. Some of the universal applications are the following −

  • Roller coaster

  • Simple Pendulum

  • Gun Fire

  • Electricity into Mechanical motion

  • Newton’s Cradle

  • Hydroelectric power plant

  • Action of speaker converting electricity into sound

Q3. When was the first time the concept of the law of conservation was introduced?

Ans. The first law of conservation was the conservation of mass which was represented by Antoine Lavoisier in 1789. After that in 1850, William Rankine gave the law of conservation of energy.

Q4. Why do we need laws of conservation?

Ans. We make lots of studies on natural and some other artificial phenomena to understand their nature and stability. So, to examine whether the process is feasible or not we use the conservation laws.

Updated on: 26-Apr-2023


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