29 Example Of Law Of Conservation Of Mass: Detailed Explanations

Law of Conservation of Mass states that “The mass can never be created or destroyed but it can only be transformed in some other form.”

In this article, we are going to discuss the various example of law of conservation of mass with detailed explanations listed here as follows:-

Mixing Two Components

When you are adding water to milk, you lose neither water nor milk. Mixing two or more components together doesn’t change the actual mass of the components. The total mass added remains the same on mixing.

Broken Glass

Consider a glass dropped from the hand accidentally and breaks into pieces.

Broken Glass;
Image Credit: Pixabay

If you weigh the mass of all the pieces of glass then you will find that the mass of the glass pieces is the same as that of the glass before it broke. The mass of the glass doesn’t vary even if it breaks.

Drilling Wood

Drilling means making a hole in a wooden plank to nail it. As a drill passes through the wooden plank, it makes its way through removing a part of the wood in the form of a powder while drilling using male type screws.

example of law of conservation of mass
Drilling a wood;
Image Credit: Pixabay

Hence, the mass of the wood doesn’t change, which is a sum of the wooden plank and the wooden powder formed on drilling it.

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Water Evaporation

The water is evaporated when the temperature of the volume of the water is more than compared to the surrounding temperature.

Water Evaporation;
Image Credit: Pixabay

The mass of the water does not change even after the evaporation, it is only transformed in the form of vapours in the air.


On burning the camphor, the solid state of camphor is converted into gas directly. This process is called sublimation. The mass of the camphor in solid state and in gaseous form also remains unchanged.


You must have noticed that on lighting the candle, the wax of the candle gets melted due to the heat supplied to the wax and which gives strength for a fire to burn. Parallelly, the melted wax runs down the candle to the ground.

Burning Candle; Image Credit: Pixabay

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It is a process of changing the solid state of a substance into a liquid state. Suppose you melt a solid cube of size 5×5×5, then you will have a volume of 125 cm3 only. The volume of the substance will not change even after melting.

Boiling Water

In boiling water, the molecule of the water is supplied with the heat energy, and the molecules on the upper layer of the water raise taking this energy. Then these particles rise up in the form of water vapour making steam of water.

Steam collected on the lid of the vessel; Image Credit: Pixabay

Here, though the mass of the water remaining in the vessel decreases, the mass in a process is conserved. A part of the volume of water evaporated in the air constitutes the remaining mass of the water.


It is a process of formation of well defined solid structures from molten or liquid substances. The mass present in the molten form is only crystallized and forms a solid crystal defining faces and planes of substances and minerals. Neither of the mass is lost in this process.

Chemical Reactions

The total number of atoms remains the same even after the chemical reaction. The mass of the reactant before the reaction takes place and after the reaction the mass of the products is equal.

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The plant takes carbon dioxide and water to prepare their food in presence of sunlight and produces glucose and oxygen. If you calculate the mass of the reactance 6CO2 and 6H2O you get it the same as the sum of the mass of the products C6H12O6 and 6O2.

Object in Centripetal Force

The force acting on the object circulating in the centripetal motion is equal to [latex]\frac{mv^2}{r}[/latex]. The mass of the object is conserved while moving in the centripetal force.

Acrobat performing with hula hoops; Image Credit: Pixabay

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Elongation of Object

On stretching the object, the tensional force is generated in the object due to which the object gets elongated. There is no loss in the mass of the object even after the elongation.


Compression is the opposite of tensional force, where the force is acted equal and in opposite directions towards each other. Only the density of the object defers while the mass remains the same. The shape and size of the object decrease on compressing, increasing the density as the volume reduces, keeping the mass constant.

Reflection of Light

Light is an electromagnetic wave that constitutes an energies photon. Upon incident, the energy of the photon is released on the particle on the surface of the object. This energy is grasped by the particle on the surface and the photon is reflected back. There is only the transmission of the energy of the photon but the mass of the photon does not change, it is conserved.

Burnt Wood

On burning a wooden plank the heat energy is generated and the smog is given out giving the residual remains of ash. The mass of the wooden plank before is equal to the sum of the ash and smoke.

Campfire Ash; Image Credit: Pixabay

The state of the object only turns from one form to another, but the mass of the reactant and the product remains the same.

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Condensation is a process of the combination of two or more molecules to form water. In the winter season, the water vapors evaporate into the atmosphere forming foggy weather. This water vapour has enough potential energy associated with it. It rises at height until its potential energy is reduced. These water droplets then condense into the cloud.


Breeze is a result of the temperature difference of the air in two different areas. The air from the high temperature region migrates in the cold area, and the air from the cold temperature region enters the hot areas, hence the migration of the air molecules results in the breeze. The temperature of the air molecules varies while the mass of the molecules remains the same.

Propellers on Rotating

The propellers of the drone, windmill, ceiling fans, etc. rotate due to the rotor and motor attached to the shaft. The mass of the propellers does not vary while rotating. The motion of the propellers can be defined by a centripetal force.

Ceiling Fan; Image Credit: Pixabay

Though the speed of the propellers depends upon the mass and length of the propellers, the mass of the propellers is conserved.

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Magma from Volcano Eruption

The density of the surface beneath the Earth’s crust at every depth increases down the ground as the pressure is built due to the imposition of every layer on the top. This increases the pressure and hence the temperature which is responsible for the melting of elements and minerals.

Due to this, the magma is in molten form and rises above the surface of the Earth to come at an equilibrium condition. The mass of the magma below and above the surface does not changes, only the pressure and temperature difference arrive.

Particles in Radiations

The object receives the energy of the incident photons falling on the surfaces of the object exposed to radiations. When the internal heat generated by the object reaches an epic point, this energy is then irradiated from the surfaces of the object in the form of waves and at low frequencies. The mass of the object and the incident and reflected photons are conserved during radiations.

Strumming a String

On strumming a string of a guitar, the vibrational waves are created in the string due to which the string vibrates and generates a sound. The mass of the string is conserved during the vibrations.

Vibrating strings of a guitar; Image Credit: Pixabay

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Vibrations Created in the Object

The vibrations are set up in the object when the molecules in the object are perturbed on the application of external energy. The vibration produces the back and forth movement of the molecules constituting the object. The mass of the object does not change due to the vibrations, hence we can say that the mass of the object is conserved.

Slinky Climbing Down the Stairs

The energy that is essential for a slinky to climb down the state is the conversion of the kinetic energy to the potential energy and vise versa.

Slinky; Image Credit: Pixabay

The potential energy of the slinky is converted into the kinetic energy that is required for a slinky to step down, and again converting this kinetic energy back to potential energy.

Person Sitting on Swings

The swing oscillated in a damped harmonic motion when a person sits on the swing.

Merry-go-round; Image Credit: Pixabay

The tensional force is acting across the length of the chain or rope attached to the swing along with the mechanical energy of the swing. While the mass of the person as well as the swing remains constant.

Person Standing in Gravitron

You will find the gravitron in the amusement parks, where the person is made to stand across the walls of the gravitron and the gravitron is made moved in a circular motion increasing its speed every time until the centrifugal force acting on the person’s body becomes high enough to cancel the centripetal force to avoid the person falling in the middle of the gravitron. This keeps the person’s body attached to the walls of the gravitron even after the wall beneath the feet of the person is removed.

Object Rose at Heights

The gravitational potential energy of the object increases when rosed at a height above the ground. Though the potential energy of the object increases, the mass of the object is conserved throughout.

Hot air balloon; Image Credit: Pixabay

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Object Falling from Heights

Consider a mango falling from the tree. The potential energy associated with the mango is high when present on the tree. As it detached from the tree, this potential energy is converted into kinetic energy and the mango fall does towards the ground. The mass of the mango is conserved, only the energy is transformed from one form to another.


If you mix soil in the glass of water and measure the weight of the volume; and later after a while you measure again the weight of the volume once when all the soil precipitates down the surface of the glass, you will notice that the weight does not change and it is obvious. Hence, the precipitation also follows the law of conservation of mass.

Burning of Coal

When the coal is burnt, the oxygen is reacted to the burning coal to form carbon dioxide. Hence, the mass of the reactants which are carbon and oxygen combines to give a product as carbon dioxide conserving the mass of the reactants.

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Frequently Asked Questions

Can mass be converted in the form of energy?

The energy associated with the object is directly dependent on its mass.

The mass is transformed from one form of energy to another while doing some work. But the mass remains the same before and after the work is done.

How does mass is conserved in the exothermic processes?

When the heat is generated due to the breaking and formation of the bonds in a chemical reaction process, it is said to be an exothermic reaction.

The reactant reacts to give products releasing the amount of energy in the form of heat. The mass of the reactant and the products remains the same and hence the mass is said to be conserved in the exothermic process.


Hi, I’m Akshita Mapari. I have done M.Sc. in Physics. I have worked on projects like Numerical modeling of winds and waves during cyclone, Physics of toys and mechanized thrill machines in amusement park based on Classical Mechanics. I have pursued a course on Arduino and have accomplished some mini projects on Arduino UNO. I always like to explore new zones in the field of science. I personally believe that learning is more enthusiastic when learnt with creativity. Apart from this, I like to read, travel, strumming on guitar, identifying rocks and strata, photography and playing chess. Connect me on LinkedIn - linkedin.com/in/akshita-mapari-b38a68122

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