The Law of Conservation of Energy

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Introduction
Have you ever wondered why do we start to rub our
hands together the moment we start to feel a bit
cold? You know the answer, dont you? That action
heats up your hands and gives you a little bit of
comfort in that particular situation. When we
rub our hands together, we use mechanical energy
to create friction that generates heat energy. As
you may realize, the heat does not just appear
out of nowhere
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So What is the Law of Conservation of Energy?

• As you may realize, the term conservation
  refers to the principle by which the total value
  of a particular physical quantity or parameter
  remains unchanged within a system, unless the
  system is subject to external influence.
• By that definition, the conservation of energy
  means that the amount of energy within a system
  will remain unaltered over time. 

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So What is the Law of Conservation of Energy?

• There are several examples that can simplify the
  concept for you-
• When you switch on the fan in your bedroom, the
  electrical energy gets converted into the
  mechanical energy. Similarly, when you switch on
  a bulb, the electrical energy that flows within
  the wire gets converted into light and heat
  energy.

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So What is the Law of Conservation of Energy?

• The green plants use sunlight to carry out the
  photosynthesis process. It allows them to store
  the energy in their cells. In this process, the
  light energy is converted into chemical energy
  which they use for their growth and nourishment.
• In thermal power stations, the heat energy is
  converted to electrical energy. The heat,
  however, is generated from the combustion of
  fossil fuel, which is a transformation of
  chemical energy into heat energy.

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So What is the Law of Conservation of Energy?

• When you stop a ball from rolling on the floor,
  it may seem like theres no conversion of energy,
  but in reality, you absorb the kinetic energy of
  the ball and turn it into heat potential energy.
• Even when you are pushing a chair to move it from
  its static position, you are using the potential
  energy stored in your body to do the task. At
  first, your potential energy gets transferred to
  the chair.

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What does System Mean in the Context of
Conversion of Energy?

• A system can mean a lot of things in science, but
  to give the term a general outline, it can be
  said any collection of objects that we choose to
  model with our calculations is a system. When the
  matter of conversion of energy is involved, a
  system generally involves the object of interest
  and anything that interacts with it.

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What does System Mean in the Context of
Conversion of Energy?

• However, in practice, physicists often ignore
  some interactions while outlining a system for
  their convenience. Usually, the things that are
  excluded from the system are collectively
  termed as the environment.
• Even though ignoring some part of the environment
  will make the calculations less accurate, but the
  physicists continue to ignore several aspects of
  the environment while working on their
  hypotheses.

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What does System Mean in the Context of
Conversion of Energy?

• For instance, in case of air rifle shooting, the
  objects of interest are the rifle, the bullet and
  the target. But if you need to be more specific,
  you need to include Earths gravitation pull as
  well which has an influence on the motion if the
  bullet.
• Now that you have a decent idea about the law of
  conservation of energy and the concept of
  system, we can proceed to the part we discuss
  the law of conservation of energy formula.

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What does System Mean in the Context of
Conversion of Energy?

The formula of conservation of energy An object
(or multiple objects) in a closed system can have
both kinetic and potential energy. The total
energy in that system, which is the sum of the
kinetic and potential energy, is termed as total
mechanical energy. As mentioned earlier, if the
system is not subject to external influence, the
total mechanical energy remains conserved.
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What does System Mean in the Context of
Conversion of Energy?

The kinetic energy can change into potential
energy and vice versa without altering the total
energy with the system. However, when the
mechanical system is not fully closed, external
influence can change in the total mechanical
energy. The system can perform work in the
surroundings, or some work can be done on the
system. This other work is often considered as
the external influence.
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What does System Mean in the Context of
Conversion of Energy?

The following equation explains how the whole
thing is measured K1 U1 W K2 U2 In
this conservation of energy equation, K1 denotes
the initial kinetic energy in the system while U1
indicates the initial potential energy. 
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What does System Mean in the Context of
Conversion of Energy?

Interestingly, the conservation of energy also
outlines the first law of Thermodynamics. It
states that the change in internal energy of a
system is equal to the difference of the heat
transfer into the system and the work done by the
system. The first law of thermodynamics is often
explained by the following equation ?U Q W
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What does System Mean in the Context of
Conversion of Energy?

In this equation, ?U denotes the change in the
internal energy, while Q denotes the heat
transfer into the system and W the work done by
the system respectively. While this particular
law of Thermodynamics is an application of the
conservation of energy, there is another famous
formula in the field of Physics that talked about
something on the similar line. E mc2
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What does System Mean in the Context of
Conversion of Energy?

This formula of mass-energy equivalence, which
was discovered by Albert Einstein, identifies the
mass of an object as a form of energy. Mass and
energy these two fundamental quantities relate
to each other as per the formula mentioned above.
Here, E signifies energy while m denotes mass and
c stands of the speed of light (3 x 108 m/s).
This brings us to the parallel concept of
conservation of mass.
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What is the Law of Conservation of Mass?

• Interestingly, the law of conservation of mass
  was discovered by Antoine Lavoisier in 1785, 57
  years before the law of conservation of energy by
  Julius Robert Mayer. However, theres no harm in
  learning about conservation of energy before the
  conservation of mass.

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What is the Law of Conservation of Mass?

• If you are looking for the law of conservation of
  mass definition, all you need to do is repeat the
  law of conservation of energy definition and
  replace energy with mass in the statement.
• If you burn a candle in a properly sealed room,
  where nothing (not even air) can come in or get
  out, you will find that some of the melted wax
  gets deposited at the bottom of the candle

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What is the Law of Conservation of Mass?

• Einsteins Mass-Energy Relation
• In the year 1905, Einstein changed the perception
  of people reading the concept of mass with his
  theory of relativity. He established the fact
  that mass is not absolute. It can be converted
  into energy and increase significantly at
  exceedingly high speeds near that of light.

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What is the Law of Conservation of Mass?

• According to Einsteins equation of mass-energy
  equivalence, the total energy of an object
  comprises of its rest mass and the increase of
  mass caused by high speed. For any atomic or
  chemical reaction, some conversion between rest
  mass and the energy takes place. This is why the
  products of a reaction process usually have a
  smaller or greater amount of mass than the
  reactants.

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What is the Law of Conservation of Mass?

• This brings us to the idea of conservation of
  mass-energy. It suggests that the mass and energy
  associated with the object (or objects) within an
  isolated system remain unchanged in quantity.
  Though, these elements (mass and energy) can be
  converted into one another within the system.

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What is the Law of Conservation of Mass?

• During the event of nuclear fission or nuclear
  fusion, some mass of the nucleus turns into a
  massive amount of energy. This explains why a
  certain amount of mass goes missing from the
  total mass of the original particles once the
  event is completed. The binding of nuclei
  generates massive energy which is used in nuclear
  power plants and often as nuclear weapons.

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