What Is Conserved In Physical Changes Shape Energy Mass Density? Discover the Essential Principles Here!

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Physical changes are all around us, from the way water flows to how objects take shape. Have you ever wondered what principles govern these changes?

In this article, we explore the concept of conservation in physical changes and how it relates to key factors such as shape, energy, mass, and density. By understanding the basics of conservation, you can better grasp the laws that shape our world and make sense of everyday phenomena.

“Conservation laws give us a powerful tool for understanding the natural world. By looking at what stays the same during a physical change, we can predict how things will behave and interact.”

Whether you’re a student learning about physics for the first time or an experienced scientist looking to deepen your knowledge, this article presents essential concepts in an accessible and engaging way. From simple examples to more complex applications, we’ll guide you through the fundamentals of conservation in physical changes.

By the end of this article, you’ll have a clearer understanding of why certain properties remain constant in physical changes and how this impacts everything from the movements of celestial bodies to the behavior of molecules.

So let’s dive into the world of conservation and discover the essential principles behind physical changes!

The Law of Conservation of Mass

Physical changes are those that do not result in the formation of new chemistry. The physical changes involve a change in a certain characteristic of a given chemical substance, such as size, shape or energy level, but the composition remains unchanged. There are several characteristics which remain conserved during physical changes: mass, density, and energy. Among these, the most prominent one is mass. Let’s explore what is conserved in physical changes relating to mass.


The law of conservation of mass states that in any closed system, the total amount of mass remains constant over time, regardless of any transformation or reaction occurring within this system. This means that although a physical change may occur (such as phase transitions or dissolutions), the total amount of matter present before equals the amount present after the change. In other words, no matter can be created or destroyed – it merely undergoes a transformation from one form to another.

“Mass can neither be created nor destroyed” -Antoine Lavoisier

This principle has been widely recognized since its formulation in the late 18th century by French chemist Antoine Lavoisier, who is often considered the father of modern chemistry. He observed that during combustion reactions, the total weight of reactants and products remained roughly constant, indicating that there was something fundamental about the nature of matter itself.


To illustrate how the law of conservation of mass applies in everyday life, consider some examples:

  • A melting ice cube still has the same mass as the original solid block of ice because water is just changing its state from solid to liquid
  • If sugar is dissolved in water, the total mass of the solution will equal to the sum of the masses of sugar and water before being mixed, as no matter has been created or lost
  • A balloon filled with air is not increasing in mass if it inflates because all the mass comes from the surrounding air molecules that are pushed into the balloon!
  • In a chemical reaction, the total mass of reactants should be equal to the total mass of products. For instance, when ammonium nitrate explodes, it decomposes into nitrogen gas, oxygen gas, and water vapor. The mass of the nitrogen, oxygen, and water molecules together equals the mass of the ammonium nitrate prior to burning.


The concept of conservation of mass applies to fields beyond physical chemistry, such as physics, astronomy, and biology. Here are some applications:

  • In nuclear science, this law allows physicists to know how much energy will be released during reactions since there is a precise mathematical relationship between energy and matter according to Einstein’s famous equation E=mc2
  • Astrobiologists often use the principle of mass conservation to explain the formation of stars and galaxies over time
  • When astronauts consume food in space stations, they need to minimize waste materials which come out from their bodies. A closed-loop life support system can re-use every drop of liquid and atom of solid waste by applying several technologies including catalytic combustion processes while adhering to the law of conservation of mass.

The importance of understanding this fundamental law cannot be overstated since its scope extends far beyond pure chemistry. Mastery of the lab procedures and calculations that govern its implementation form the bedrock for progress in many scientific disciplines. Whether you’re a chemist investigating new drugs or an astrophysicist studying distant stars, all scientists share a deep appreciation for the conservation of mass.

The Law of Conservation of Energy

The law of conservation of energy is a fundamental principle in physics that states that the total amount of energy in an isolated system remains constant over time. In simpler terms, energy cannot be created or destroyed – it can only be transformed from one form to another.

This principle was first recognized and formulated by the German physicist Hermann von Helmholtz in the mid-19th century. The law has since been tested extensively through countless experiments and observations, and it is now widely accepted as one of the most fundamental laws in all of physics.

Forms of Energy

There are many different forms of energy, including thermal (heat), chemical, nuclear, gravitational, electrical, and electromagnetic radiation.

Thermal energy is produced when the motion of particles within a substance increases, while chemical energy is stored in the bonds between atoms and molecules in compounds.

Nuclear energy is released through the process of nuclear fission or fusion, while gravitational energy is associated with the attraction between objects with mass.

Electrical energy is produced by the movement of charged particles, such as electrons, while electromagnetic radiation consists of oscillating electric and magnetic fields that travel through space at the speed of light.

Energy Conversion

Energy conversion refers to the transformation of energy from one form to another. This phenomenon occurs constantly in our daily lives and across a wide range of natural processes.

For example, when we turn on a light bulb, electrical energy is converted into light and heat energy. When we burn fossil fuels to generate electricity, chemical energy is converted into thermal and electrical energy.

The laws of thermodynamics dictate that whenever energy is converted from one form to another, some of it will inevitably be lost to the surrounding environment in the form of waste heat or other forms of energy that cannot be harnessed for useful work.

Renewable Energy

With concerns about climate change and the depletion of nonrenewable resources such as oil and coal, there has been a growing interest in developing alternative sources of energy that are sustainable and environmentally friendly.

The term “renewable energy” refers to energy sources that come from natural processes that can be replenished over time, such as solar, wind, hydro, geothermal, and biomass energy.

While renewable energy technologies have made significant strides in recent years, they still face challenges with scalability, reliability, and cost-effectiveness when compared to traditional fossil fuels. Nevertheless, many experts believe that investing in renewable energy is crucial to ensuring a clean and sustainable future for our planet.

“Energy cannot be created nor destroyed. It can only be transformed from one form to another.” -Albert Einstein

The Law of Conservation of Momentum

In the world of physics, one of the fundamental concepts is conservation. In this context, conservation means that something cannot be created or destroyed; rather, it can only change form or location. This concept is particularly relevant to momentum, which is a measure of an object’s motion and energy.


The law of conservation of momentum states that the total momentum of a closed system remains constant if no external forces act on it. In simpler terms, if two objects collide with each other and stick together, their combined momentum will be equal to the sum of their individual momentums before the collision.

This law applies not just to collisions, but to any situation where there are multiple interacting objects. For example, if a rocket ship fires its engines and expels gas in one direction, the momentum of the expelled gas will be equal and opposite to the momentum gained by the rocket ship in the opposite direction.

It’s important to note that this law only holds true for closed systems – in other words, systems where there are no external forces acting on them. If there is friction, air resistance, or any other kind of external force present, then the total momentum of the system may not remain constant. However, even in these situations, the law of conservation of momentum still provides a useful framework for understanding how momentum behaves.

Conservation of Momentum in Collisions

When two objects collide with each other, their momentum before the collision is determined by their mass and velocity. After the collision, their momentum is again determined by their mass and velocity – but now, they may have different velocities than they did before.

One common type of collision is an elastic collision, where both objects bounce off each other without losing any energy. In this type of collision, the magnitudes of the momentums of the two objects before and after the collision will be equal. However, their directions may change – for example, if a billiard ball hits another billiard ball at an angle, they may both bounce off each other at different angles.

Another type of collision is an inelastic collision. In this type of collision, some energy is lost as heat or sound when the objects collide, so their combined momentum after the collision will be less than their total momentum before the collision. For example, when a car crashes into a wall, the metal crumples and some of the energy is released as heat and sound, causing the car’s velocity to decrease.

The law of conservation of momentum is a fundamental principle that helps us understand how objects interact with each other and transfer energy. Whether you’re studying physics for fun or for your career, it’s essential to have a solid understanding of this concept in order to make accurate predictions and calculations about how systems will behave.

“The conservation of momentum is nothing else but the law of inertia written in another form.” -Henri Poincare

The Law of Conservation of Angular Momentum


The Law of Conservation of Angular Momentum is a fundamental principle in physics that states that the total angular momentum of an isolated system remains constant, provided no external torque acts on it. Angular momentum is a vector quantity that describes the amount of rotational motion possessed by an object or system. It depends on both the mass and distribution of matter within the system as well as its velocity.

This law is analogous to the Law of Conservation of Linear Momentum, which states that the total momentum of an isolated system remains constant unless acted upon by an external force.

Applications in Astronomy

The Law of Conservation of Angular Momentum has significant applications in astronomy, particularly in understanding the motions and behavior of celestial bodies:

  • Kepler’s Laws of Planetary Motion: Johannes Kepler used observations of planets to derive his laws of planetary motion, including the observation that they move faster when closer to the sun and slower further away. This variation in speed can be explained by conserving angular momentum.
  • Planetary Migrations: Scientists have observed that some planets appear to migrate towards their host star whilst others are often found orbiting significantly further than expected from current models. It’s been suggested a mechanism to explain these behaviors is what’s called “tidal interactions.” These interactions affect the rotation of each body involved and thus can alter the conservation of angular momentum.

Conservation of Angular Momentum in Rotational Motion

Rotational motion is where the body operates under centripetal force, meaning that it orbits around a center point due to the balance between a central force and this acceleration. The law of conservation holds true here as well.

An example of this can be observed in the figure skating. A skater starts out spinning with their arms stretched making them slow, as they pull both arms to their chest (conserving angular momentum because mass is closer to the axis of rotation), and therefore spin faster.

“Angular momentum conservation is just a manifestation of the underlying laws of physics that don’t change.” -Neil deGrasse Tyson

The Law of Conservation of Angular Momentum is a critical principle in the field of physics that describes how rotational motion works in different situations, from celestial bodies down to small-scale objects like those in sports or daily life activities. This law provides an essential insight into the fundamental laws of nature that remain constant throughout time and space, much like many other conservation laws that exist within our universe.

The Law of Conservation of Charge

The fundamental principles that govern physical and chemical changes in the universe are based on a set of conservation laws. One such law is the law of conservation of charge, which states that electric charge can neither be created nor destroyed; it can only be transferred from one object to another or transformed from one form to another.

This law plays an essential role in many aspects of life and scientific inquiry, particularly in electromagnetism and particle physics, where it provides critical insights into how different particles interact with each other and the broader environment.


The law of conservation of charge states that the total electric charge in an isolated system remains constant over time. This means that if two objects come into contact, they will transfer charge until their charges balance out. For example, when you rub a balloon on your hair, negative electrons move from your hair onto the surface of the balloon, giving it a negative charge. Similarly, if you touch a metal object with an opposite charge than yours, electrons will flow to or away from you to help equalize the charges between the two objects.

In short, whenever there is an electrical interaction between charged particles or systems, the net electrical charge before and after that interaction must be the same for the entire system.

Conservation of Charge in Electromagnetic Interactions

The law of conservation of charge finds widespread application in various electromagnetic interactions. These include magnetic fields, forces between charged bodies, capacitance, and induction phenomena. The principle underpins Maxwell’s equations, which explain how varying electric and magnetic fields around an object produce and transmit electromagnetic radiation – light waves, radio waves and microwaves included. Charge conservation ensures that any changing electric field produces complementary changes in the magnetic field, thus making sure that the total amount of charge remains constant.

For instance, suppose a charged particle moves through an electromagnetic field that creates waves in both the electric and magnetic fields around it. In that case, the conservation law dictates that the sum of all positively charged particles’ movements – any movement to gain or lose electrons- must balance out negatively-charged ones even as they form a current that may move toward a conductor.

Charge Conservation and Particle Physics

The law of charge conservation plays equally vital roles in the study of subatomic particles and their interactions—the world of quantum mechanics and its seemingly bizarre properties rebelling against our everyday experiences with objects in space. In describing the behavior and interaction of elementary particles like protons, neutrons and electrons, one of two labels usually applied; each given based on either the parity-invariance concept (P) or the conservation of charge conjugation signs (C). Together these ideas are used for the mapping of observations into mathematical models developed from advanced statistical mechanics models. The laws governing neutral particles require them to exist and follow further restrictions than usual for charged particles since they do not experience electrical forces. Charge conservation remains essential in explaining how fundamental particles change forms during various kinds of reactions between similar entities or annihilation phenomena. The equations allow physicists to account for conservation of energy/momentum within such systems despite losing mass due to the production of light, neutrinos or other modes of energy transfer not related otherwise.

Charge Conservation in Chemical Reactions

In chemical reactions, balancing charges remain crucial to ensuring that all matter ultimately follows the same principle of maintaining overall electrical neutrality. That’s why chemists always ensure total positive charge equals total negative ones in balanced cycles ranging from simple ion exchange reactions to more complex structures-driven by entropy-favouring mechanisms. Chemical bondings occur because there is mutual attraction and repulsion taking place between charged electrons and nuclei in atoms. The transfer of electrons from one atom to another can create an imbalance in charge throughout a molecule or reaction, with charges flowing until they ultimately balance out. Understanding this property helps chemists predict how different chemicals might interact with each other to form new compounds. Ultimately, charge conservation holds the key to understanding several fundamental processes across various scientific disciplines, including electromagnetism, particle physics, and chemistry. Accurately describing these phenomena requires mathematicians and theorists to develop models and theories that help explain how charged particles interact within systems – a crucial step in advancing diverse fields of science.

Frequently Asked Questions

What is conserved in physical changes?

In physical changes, the amount of matter remains constant. This means that the mass of the substance before and after the change remains the same. However, the physical properties of the substance may change, such as its shape, size, or state of matter.

What happens to shape during physical changes?

During physical changes, the shape of a substance may be altered, but its chemical composition remains the same. For example, melting a piece of ice changes its shape from a solid to a liquid without changing its chemical composition. Similarly, bending a metal rod changes its shape without altering its chemical makeup.

Is energy conserved in physical changes?

Energy is conserved in physical changes. Although the physical properties of the substance may change, the total amount of energy in the system remains constant. For example, when ice melts, energy is absorbed to break the bonds between the water molecules. This energy is released when the water freezes again.

What is the effect of physical changes on mass?

Physical changes do not affect the mass of a substance. The amount of matter in the substance remains constant before and after the change. This means that the mass of the substance is conserved, even if its physical properties, such as its shape or state of matter, are altered.

How does density change during physical changes?

The density of a substance may change during physical changes, depending on the nature of the change. For example, the density of water increases when it freezes because the molecules are packed closer together. Similarly, the density of a gas decreases when it is compressed because the molecules are forced closer together, reducing the space between them.

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