# What Is The Law Of Conservation Of Energy?

By Antonia Čirjak on February 26 2020 in Environment If two or more objects or particles collide, the sum of energy that was there before the collision remains the same after it. Image by Michal Jarmoluk from Pixabay
• The Law of conservation of energy explains energy as a constant in the interaction of objects.
• Kinetic energy approaches zero whenever an object starts slowing down, reaching it upon full stop.
• Energy is, when we look at it from Einstein’s interpretation, a multiplication of mass of an object and the square of the speed of light.

The law of conservation of energy is used in physics to explain how energy remains constant when two or more objects that have mass interact with each other. If two or more objects or particles collide, the sum of energy that was there before the collision remains the same after it.

## If It Moves, It Has Energy

Several key factors contribute to the construction of this law. Concepts of gravity and potential energy are crucial to understanding how this works. First of all, imagine gravity as a force that is pulling everything down. Now, think of kinetic energy as a container that has more or less potential, depending on the speed and mass of the object. Any kind of object that travels against gravity will store its energy into potential energy.

So, a simple conversion happens - as an object slows down, it loses speed because of the effect gravity has. At the same time, the amount of potential energy goes up. If and when the body starts moving back down, going in favor of what gravity wants it to do, that potential energy is converted back into kinetic.

## Energy Changes Forms

Imagine if you threw a tennis ball directly above you. At one moment, when the ball reaches its highest point in the air, the amount of kinetic energy that the ball has is zero. All of the energy that the ball contains is now potential. That potential is immediately released as the ball starts falling, with gravity pulling it all the way.

All of this explains how all energy can change its form and is not created or destroyed. This is, as vastly put as it can be, the first law of thermodynamics. This does not mean that energy can not be lost or dissipated. The law of conservation of energy applies in controlled environments or at least the ones that do not involve friction. When friction is present in any kind of movement, it slows down the object, which results in energy loss.

## Impossibility Of Perpetual Motion?

This law has, at least by today’s advancements in contemporary physics, proved how Perpetuum mobile is not possible. Perpetual motion, as this Latin phrase would translate, simply expresses an ideal-type object: one that would move forever, without any kind of power source.

This law, in essence, explains how mass and energy could be viewed as equivalents. With Einstein, and relativity influencing the way scientists started to think about systems around us, this law is more known as the Law of conservation of total energy.

## ‘’E Equals MC Squared’’

If we take a look at one formula that one Einstein’s formula everyone knows, E=mc2, we can see how the Law of conservation of energy is present here. In this equation, E means energy, and the m stands for mass. They stand on the different sides of the equation, which means that talk about the same thing when that squared speed of light is finally added. The same reasoning can be applied even when we take a look at nuclear reactions, which was something of Einstein’s interest as well.

You would think that in a nuclear reaction, or a nuclear explosion, some energy must be lost and gone forever. Conservation of mass (and if the mass is viewed as energy) holds up in those situations also. The mass of atoms that were there before the nuclear reaction, with tremendous amounts of energy that usually come when we split the atoms, remains there even after the reaction.