Law of Conservation

The law of energy conservation has many practical applications that one might have come across in real life. When you use a flashlight that runs on a battery, the chemical energy of the battery gets converted into electrical energy that lights up the flashlight while producing heat and light energy. Unless and until any external support of energy is not provided, the existing energy gets converted in order to get the work done. 

The law of conservation of energy reiterates and emphasises the same. The energy is neither created nor destroyed, the existing energy gets converted into a different form of energy. 

Energy

In the 21st century, the world cannot imagine a life without energy in it. Humans wake up, start the use of energy right away. The morning alarm clock that wakes up everyone, uses energy to function. The light bulbs that enlighten your household makes use of the energy. Even your own body uses biological energy to function properly. Scientifically defined, energy is the ability to do work. The forms in which energy is available to us are heat, electrical, light, motion, chemical and gravitational. 

The forms of energy can be further classified into kinetic and potential energy.

Sources of Energy

In nature, one can obtain energy from two sources. One is renewable sources and the other is non-renewable sources. 

Renewable Sources of Energy: Renewable or clean sources of energy are a broader category for all the sources of energy that are renewable or replenished by natural processes. The most common examples of renewable sources of energy are solar energy, wind energy, hydropower, biomass etc.

Non-Renewable Sources of Energy: Non-renewable sources of energy are those that once exhausted, will take millions of years to get replenished. Given the population pressure and the increased dependence on the non-renewable sources of energy by humans, this source of energy is already on the verge of exhaustion. The major examples of non-renewable sources of energy are coal, natural gas and petroleum, together known as fossil fuels.

Types of Energy

As mentioned above, the forms of energy are more typically classified into kinetic and potential energy. 

Kinetic Energy: Simply explained as the energy that any object gets due to it being in motion is referred to as Kinetic Energy. More formally, kinetic energy is defined as the form of energy in which the object or particle gains energy by being in motion. The kinetic energy also is dependent on the mass of the object. 

Potential Energy: Potential energy is also known as stored energy as it works completely opposite to kinetic energy. The potential energy is defined as the form of energy that is derived by an object from being in the same position for an interval of time. It also depends upon various positions of the parts of the system. 

Law of Energy Conservation

The law of energy conservation states that energy in its truest form cannot be created nor destroyed. It can only be converted from one form to another. This stated law is followed by all the forms that energy exists in and there have not been any violations identified by the researchers.

The total energy in any form is determined by the following equation:

UT=Ui+W+Q

In the equation,

UT is the total amount of energy present 

Ui is the initial energy

W is the work done

Q is the heat 

Derivation for the Law of Conservation of Energy

Case I- Conservation during a freefall of the body

Assumption: Suppose there is an object of man m raised to a height h above the ground. As it is raised to a height, the object will be gaining potential energy. Now, assume that the object is now in freefall. As it starts falling, energy conversion takes place and the stored potential energy gets converted into kinetic energy. After reaching the ground, the final energy conversion takes place and the kinetic energy is turned into potential energy again.

• At height h

 Total Energy (TE)=Kinetic Energy (KE)+Potential Energy (PE) ………………….(i)

Potential Energy (PE)= mgh

Kinetic Energy (KE) = 0

At h, the object has zero velocity

Now 

In (i),

TE=0+mgh or TE=mgh

• At height (h-x)

Now assume that the object has travelled a distance of x, now the height is (h-x)

u=0

v2-u2=2as

v2-0=2g(x)

v2=2gx

KE=12mv2 or KE=12m(2gx) or KE=mgx

PE=mg(h-x) or PE=mgh-mgx

TE=KE+PE or TE=mgh-mgx+mgh

TE=mgh

• When the object finally reaches the ground, height becomes 0 and hence the potential energy becomes 0.

KE=12mv2

v2-u2=2as

v2-0=2g(h)

v2=2gh

KE=12mv2 or KE=12m(2gh) or KE=mgh

PE=0

TE=KE+PE=mgh

Law of Conservation of Mass

Similar to the law of conservation of energy, the law of conservation of mass states that the mass can neither be created nor destroyed in a chemical reaction. In an equation, both sides should have the same mass. Breaking it down even deeper, the mass of the element present over both sides of the equation should be equal and unchanged.

Examples for the Law of Conservation of Energy

For better understanding, let’s take a look at a few examples of the law of conservation of energy:

• Ramesh is in the library and he pushed a few books on the other side of the table to make more room for other books. The energy transferred from his arms to the books which made them move.
• Aayushi was running in the hallway and bumped into Ishika causing both of them to fall. Here, Aayushi’s energy get transferred to Ishika which made her fall

Conclusion

The entirety of science is based on strict principles and laws. One such law is the law for the conservation of energy. The law strictly implied that energy cannot be created nor be destroyed. It can only be converted from one form to another.