Living creatures seek energy to sustain life, where human civilization needs the energy to work obtained from sources such as fossil oil, nuclear power or solar energy. Also, the planet’s atmosphere and ecological cycles are powered by Earth’s radiant and geothermal energy.

Energy is the quantitative property of physics that must be applied to an object to operate on it or heat it. Energy is a conserved quantity. The law of conservation of energy states that energy can neither be created nor destroyed but can only be converted from one form to another. The SI unit of energy is Joule.

One of the fundamental principles of physics is the law of energy conservation. In a chemical reaction, it controls the microscopic motion of individual atoms. According to the law, “In a closed system, i.e., a system that is isolated from its surroundings, the total energy of the system is conserved.” The law states that, even if energy transformation occurs, the whole energy is conserved in a system. Energy cannot be generated or lost; it can only get transformed from one form to another.

While several forms of energy exist, they are generally classified into kinetic energy and potential energy.

• Kinetic energy
  The kinetic energy of an entity in physics is the energy it has due to its motion. It is classified as the work required to drive a specific mass body from rest to its specified velocity. After gaining this energy through its acceleration, the kinetic energy is maintained by the body without changing its rate. As the body decelerates from its current pace to a state of rest, it does the same amount of work it has done while going to that pace from rest.The kinetic energy of an object at motion is given by:K.E = ½ mv², where m is the object’s mass while v is the speed with which it moves.

  
  The S.I. unit of kinetic energy is Joule, whereas the English engineering unit is foot-pound.
  
  

• Potential energy
  The potential energy in physics is an object’s energy regardless of its location concerning other things, pressures, electrical charges, or other variables within it. Potential energy correlates with forces acting on a body, such that their overall work on the body only depends on the original and final locations of the body in place.Potential energy is further categorized into two different types: gravitational potential energy and elastic potential energy. Gravitational energy potential is an energy in an object which is retained vertically because of the gravitational force that works to bring it down. Elastic potential energy means energy in items, such as trampolines, rubber stripes and bungee cords, which can be extended or compressed. The longer an entity can spread, the more elastic energy it possesses.The potential energy formula relies on the force that works on different bodies. For the gravitational force, the formula is P.E. = mgh, where m is the mass in kilograms, g is the acceleration due to gravity (9.8 m / s² the Earth’s surface), and h is the height in meters.

The concept of work is somewhat smaller than the usual definition of the word. Work on an object is achieved as the force applied pushes it across a path. An individual holding a heavyweight does not work because the force does not move the item from a distance.

In our daily language, the work done is attributed to muscle effort in doing a particular task, while this is not the case with physics. According to the physical definition, work is carried out as the heavyweight is moved from a stationary position.

The SI unit of work is known as Joule (J), named after the English physicist James Prescott Joule from the 19th century, which is now described as the work needed to generate a displacement of one metre by exerting a force of one Newton.

Like energy, we hear a lot about the word power. There are some differences between energy and power. It has a broad multitude of interpretations in daily life. But it has a unique significance in physics, where the rate at which work is done is defined as power.

Power often depends on work; even if a person works at various rates, his power varies at specific intervals. Here the principle of average power is taken into consideration.

The average power can be defined as the total consumption of energy divided by the entire time. In simple words, we can conclude that average power is the average work per unit of time. The rate at which work is performed on an item is known as power, and it is a quantity dependent on time. That’s how quickly a job is done. The powder formula is expressed as:

Power = Work done/ Time taken to complete the work or P = W/t

The S.I unit of power is joule/ second.

Energy transfer refers to energy flow from one spot to another. In contrast, energy transformation in common daily life situations involves energy change from one type to another, for example, from kinetic energy to energy or from potential energy to kinetic energy. Some examples of energy transformation are:

• The energy to move from one place to another is achieved by converting food’s chemical energy into mechanical energy.
• The phenomenon of lightning converts electrical energy into light, sound and heat energy.

For life and other living things, energy is crucially important. The sun is the origin of all the life on Earth, either directly or indirectly. It is vital to choose our energy sources carefully to influence our natural systems on Earth in ways we are maybe uncertain of.

1. Why is renewable energy so important?
   When the whole life cycle of technology is taken into account, specific renewable energy sources result in little to no pollution. No or low air pollutants generate green energy.
   
2. What is the difference between energy and power?
   The fundamental difference between energy and power is that energy seems to be what changes are happening that can be transferred through one component. In contrast, power is the rate at which energy is transmitted.
3. How is energy generated?
   Steam turbines produce much energy with fossil fuels, thorium reactors, biofuels, hydroelectric, and solar power energy.
4. How is work calculated in simple cases?
   The calculation of work done in simple cases is by the formula,Work = Force x Distance.