What is the Law of conservation of energy?

The Law of conservation of energy can be defined in 2 ways;

“The law in which energy can neither be created nor destroyed but can be changed from one form to another is called the Law of Conservation of Energy“

OR

“The sum of all energies of a closed or isolated system remains constant but can be changed from one form to another depending upon their position (Potential Energy) or motion (Kinetic Energy). This is called the Law of conservation of energy”

How can we find the Total amount of energy of any system?

Mathematically, the total amount of energy of any system can be written as;

U_T = U_i + W + Q

Where;

• U_T is the total amount of energy of any system
• U_i is the initial amount of energy before any work done
• W is the amount of work done on the system or by the system
• Q is the amount of heat added to the system or removed from the system

History of the Law of conservation of energy

Many scientists contribute to the discovery of the Law of conservation of Energy. Let’s have a look at the details step by step;

• Isaac Newton
  Sir Isaac Newton, an English physicist, and mathematician were one of the first people to work on the idea that energy is always the same. Newton showed in his laws of motion that energy is conserved, which means that the total amount of energy in a closed system stays the same over time.
• Hermann von Helmholtz
  Helmholtz’s work and personality acted as a “bridge” between himself and the top British scientists, if not between British and German science in general. This relationship made it easier for British scientists, especially younger ones, to visit Helmholtz in Heidelberg and Berlin. It also helped Maxwell’s electromagnetic theory (and British physics in general) get more attention in the German-speaking world. It was a key factor in negotiating electrical standards in the last third of the 19th century. And Helmholtz’s lectures in Britain made it easier for British scientists to understand the work being done in Germany. This article focuses on how that relationship grew and changed during the 1850s and 1860s when the law of conservation of force was solidified and made more well-known. Over time, the law of conservation of force changed into and became known as the law of conservation of energy, to which Helmholtz and others made important, even fundamental, contributions. That law was made in part by people from both England and Germany, as well as a number of people from other places, who all made important or less important contributions. Hermann von Helmholtz, a German physicist, and mathematician, built on Newton’s work and came up with the modern version of the principle of energy conservation in the middle of the 19th century. Helmholtz showed that energy is a scalar quantity that can change from one form to another but cannot be created or destroyed.

• Nicolas Léonard Sadi Carnot
  Nicolas Léonard Sadi Carnot, a French physicist, also helped to come up with the idea that energy stays the same. Carnot’s work on thermodynamics showed that energy can change from one form to another, but the total amount of energy in a closed system can’t go up or down.
• James Clerk Maxwell
  Lastly, the Scottish physicist James Clerk Maxwell added to the principle of energy conservation by showing that energy, like charge and mass, is a foundational element of the universe. Maxwell’s work resulted in the establishment of the field of electromagnetism and laid the groundwork for modern physics.

Working Principle of Law of conservation of energy

This energy conservation Law is based on the 1st Law of thermodynamics which is stated as;

“Energy is always stored in a thermodynamic system, maybe in different forms like heat, work or some other energy types”

For Instance;

• If we throw a ball into the air, it has kinetic energy because it is moving. As it goes up higher and higher, it loses more kinetic energy and gains more potential energy. When the ball is at its highest point, it no longer has any kinetic energy; it only has potential energy. As it falls back down to the ground, it changes its potential energy back into kinetic energy.
• In the same way, when you turn on a light bulb, electrical energy changes into light energy and heat energy. When a car engine is running, the chemical energy in the fuel is turned into mechanical energy that moves the car forward.

Derivation of Law of Conservation of Energy

Let us consider a body having mass “m” which is at some height “h” as shown in the below figure.

At heighest point A the Potential Energy of the body is maximum due to its position and Kinetic Energy of the body is Zero. So,

E = mgH …… eq(1)

When the body comes down to point C, the Kinetic Energy which is stored in the body will be maximum and its Potential energy becomes Zero but in the middle position at point B, the body will have both energies like Kinetic energy as well as Potential energy.

E = K.E + P.E

P.E = mgX …… eq(2)

As we know the third equation of motion is;

K.E=mg(H-X)…… eq(3)

By using equation 1,2, and 3 we get;

E = mg(H – X) + mgX

E = mg(H – X + X)

E = mgH

In the same way, if we look at the energy at point C, which is at the bottom of the tree, we get mgH. As the fruit falls to the bottom, we can see that the potential energy is changing into kinetic energy. So there must be a point where potential energy and kinetic energy are equal. Let’s say we need to figure out how high that is above the ground. At that point, we know,

K.E = P.E

As we know that the body is at height from the ground;

P.E = mgX …… eq(5)

By using equation 4 and 5, we get

So, H/2 will be called as a new height.

Examples of Law of Conservation of Energy

• Torch
  In a torch, the chemical energy of the batteries is turned into electrical energy, which is then turned into light and heat energy.
• Hydroelectric power plants
  In hydroelectric power plants, waterfalls fall from a height onto the turbines. This makes the turbines turn, which makes electricity. So, the water’s potential energy is turned into the kinetic energy of the turbine, which is then turned into electricity.
• Loudspeaker
  In a loudspeaker, electric energy is turned into sound energy.
• Microphone
  In a microphone, the energy from sound is turned into electricity.
• Generator
  A generator is a piece of equipment that turns mechanical energy into electrical energy.
• Fuels
  Chemical energy is turned into heat and light when fuels are burned.
• Food
  When food is broken down in the body, it is turned into thermal energy, which is used to keep the body warm.
• Pendulum
  The Law of Conservation of Energy is shown by the way a pendulum swings back and forth. As it goes higher and higher, it gains potential energy, which is stored energy. When it comes back down, that potential energy is turned into kinetic energy (the energy of motion).
• Roller coaster
  Another thing that shows how the Law of Conservation of Energy works is a roller coaster. As the roller coaster goes up the track, it gets more energy. When it gets to the top and starts to go down, that potential energy turns into kinetic energy. As the coaster goes down the track, it gets faster.
• Car engine
  The Law of Conservation of Energy is shown in a car engine by the way that fuel burns. As the engine runs, the chemical energy in the gasoline is turned into thermal energy (heat) and kinetic energy (motion).
• Stars Formation
  The Law of Conservation of Energy is also shown by the way stars are made. As gas and dust clouds get closer together because of gravity, they gain potential energy. As the clouds get thicker and hotter, the potential energy is turned into thermal energy. This starts nuclear fusion, which releases a lot of energy as light and heat.

Applications of Law of Conservation of Energy

Few applications of Law of conservation of energy are as follow;

In the Field of Mechanics

The law of conservation of energy can be applied in the field of Mechanics to study the motion of objects and thier predictions such as Projectile motion which is based on velocity and height of the object.

In the Field of Thermodynamics

The law of conservation of energy can be applied in the field of Thermodynamics to make energy systems This law is used in this field to calculate the quantity of energy that is converted into work or the quantity of energy that is lost from the energy system.

In the Field of Chemistry

The law of conservation of energy can be applied in the field of Chemistry to inquire about quantity of energy realead or absorbed during the Chemical Reaction so that we could be able to find the ease of reaction and required necessary conditions to occur.

In the Field of Electrical Engineering

The law of conservation of energy can be applied in the field of Electrical Engineering so that we could be able to analyze and design Electrical Circuits. In this field, it is used to calculate the efficiency of the circuit and amount of energy lost from the circuit in the form of Heat.

In the Field of Astrophysics

The law of conservation of energy can be applied in the field of Astrophysics to determine the act of Stars and Galaxies. This Law is used for the understanding of energy transferring in these systems and amount of energy released when Astronommical Events occur.

What is Conservation of Energy?

The process in which we made some act to Reduce the Consumption of Energy in an environment is called Conservation of Energy.

How can we conserve energy in our daily life?

We can conserve the amount of Energy in our daily life by the following ways;

• Change the way you do things every day so that you turn off devices and appliances when they’re not in use. Buy gadgets and appliances that use less electricity.
• Smart power strips can be used: Do you know that appliances use power or energy even when they’re not being used? Yes, things that draw power from outlets are called “phantom loads.” These smart power strips will help you save energy and cut down on costs from phantom loads.
• One of the main things that use electricity is the refrigerator. Keep the fridge on a low setting to save energy.
• To save energy, use CFL and LED bulbs. CFL and LED bulbs are energy savers.
• When told to, clean or replace air filters. Heaters and air conditioners (AC) use more power than other appliances. When you clean or replace air filters, they work better and use less energy.
• Run the dishwasher and washer when they are full. To save the most amount of energy possible with each run cycle.
• If you use a laptop instead of a desktop computer, you can save a lot of power.
• Install showerheads that save water and power to help save hot water and save money.
• Instead of an oven, use a slow cooker, a toaster oven, or a microwave oven. Use tools made of ceramic and glass as well.
• The best way to save gas is to ride a bike.
• Saving energy is another reason to walk instead of drive.
• On a day with a lot of wind, skip the dryer and hang your clothes out to dry.

Benefits of Conservation of Energy

• Environmental benefits
  Energy conservation helps cut down on the amount of released greenhouse gases, which is the  cause of climate change. By using less energy, we can decrease the amount of fossil fuels that are burned to make electricity and power cars. This cuts down on the amount of carbon dioxide and other greenhouse gases that get into the air.
• Cost savings
  Energy conservation can help lower your energy bills and save you money. People and businesses can save money on their energy bills by using appliances and lights that use less energy, insulating their homes and buildings, and using renewable energy sources.
• Improved energy security
  By saving energy, we can use less oil and other fossil fuels that come from other countries. We can get less energy from fossil fuels and more energy independence by using renewable energy sources like solar, wind, and geothermal energy.
• Job creation
  Developing and using energy-efficient technologies and renewable energy sources can create jobs in many fields, such as engineering, construction, and manufacturing.
• Sustainable development
  Energy conservation is a key part of sustainable development, which aims to meet the needs of the present without hurting the ability of future generations to meet their own needs. We can make a better future for ourselves and future generations if we save energy and use renewable energy sources.

Energy Conservation Day

14th of December is the International Energy Conservation Day.

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