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# Energy

## What is Energy?

Last updated date: 28th Mar 2023
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In recent days, we frequently hear about energy. One fundamental focus of physics is to research energy. The energy in Physics may be generally defined as a scalar quantity related to the state or condition of 1 or more objects. Modern civilization is feasible because people have learned the way to change energy from one form to a different then use it to try to work.

### Units of Energy

As per the metric system of Units (SI), the unit of energy is alleged to be Joule (J). Energy is additionally expressed in many other units that don't belong to the SI system. A number of these units include calories, ergs, kilowatt-hours, kilocalories, and British Thermal Units. However, these will need a factor if we would like to specify them in SI units. All of those are employed in certain areas of Commerce and Science.

## Energy Sources

Energy sources are categorized as renewable or nonrenewable:

1. Renewable energy sources which will be easily replenished.

2. Nonrenewable energy sources that can't be easily replenished.

Renewable and nonrenewable energy sources are used as primary energy sources to supply useful energy like heat or they will want to produce secondary energy sources like electricity and hydrogen.

### Law of Conservation of Energy

Conservation of energy means the conservation of all varieties of energy together. Accounting all kinds of energy within an isolated system, the whole energy remains constant. The energy accounts for under two types of energy, namely K.E., K, and mechanical energy, U.

If only conservative forces act on a system, then the total energy of the system remains constant. i.e.

K + U = constant

Example of Law of Conservation of Energy

Consider the case of a straightforward pendulum of massive bob hanging at the tip of a massless rod that's pivoted at a set point. If the pendulum is given a velocity from its equilibrium position, it executes an easy periodic motion where energy is conserved in the slightest degree points.

As the bob is raised from the equilibrium point, its position above the surface of the world is increased and hence the mechanical energy is increased. it's accounted for the decrease in mechanical energy because the bob slows down while raising.

When mechanical energy is maximum (at equilibrium position), P.E. is minimum. When mechanical energy is maximum (extreme positions), K.E. is minimum. Thus, in the least points, the total energy is conserved.

### Work-Energy Theorem

This theorem states that a job done by all the forces working on a particle or body is capable of changing its mechanical energy.

Let us take an example within which a block of mass m kept on a rough surface is acted upon by a continuing force F parallel to the surface and it's displaced through x. The initial velocity and therefore the final velocity are respectively, v₀ and v.

We use energy to try and do work and make all movements. Once we eat, our bodies transform the food into energy to try and do work. Once we run or walk or do some work, we ‘burn’ energy in our bodies. There are many sources of energy that help to run the varied machines invented by man.

The discovery of fireside by man led to the likelihood of burning wood for cooking and heating thereby using energy.

As early as 4000 - 3500 BC, the primary sailing ships and windmills were developed harnessing wind energy. With the employment of hydropower through water mills or irrigation systems, things began to manoeuvre faster. Fuelwood and dung cakes are even today a significant source of energy in rural India. alternative energy is employed for drying and heating.

With the arrival of the commercial Revolution, the employment of energy within the style of fossil fuels began growing as more and more industries were founded. This occurred little by little, from the exploitation of coal deposits to the exploitation of oil and fossil fuel fields. It's been only half a century since atomic power began being employed as an energy source. Within the past century, it became evident that the consumption of non-renewable sources of energy had caused more environmental damage than the other act. Electricity generated from fossil fuels like coal and oil has led to high concentrations of harmful gases within the atmosphere. This has successively led to problems like ozone depletion and warming. Vehicular pollution is additionally a grave problem.

### Did You Know?

One of the fundamental measuring blocks for energy is termed a Btu or British thermal unit. Btu is defined because the amount of warmth energy it takes to lift the temperature of 1 pound of water by 1 degree Fahrenheit, stumped level. One Btu equals about one black-tip lucifer. It takes about 2000 Btu to create a pot of coffee. Energy can even be measured in joules (pronounced the identical way as ‘ jewels’). One joule is the amount of energy needed to lift 1 pound about 9 inches. It takes 1000 joules to equal a Btu. It might take 2 million joules to create a pot of coffee.

## FAQs on Energy

1. What is Gravitational Energy?

Ans: Gravitational energy stored in an object's height i.e. more gravitational energy is stored in the objects which are heavier and heightened. When someone rides a bicycle down a steep hill and picks up speed, the gravitational energy is converting to motion energy. Hydropower is another example of gravitational energy, where gravity forces water down through a turbine to provide electricity.

2. What is Motion Energy?

Ans: Motion energy is energy stored within the movement of objects. The faster they move, the more energy is stored. It takes energy to urge an object moving, and energy is released when an object slows down. Wind is an example of motion energy. A dramatic example of motion energy could be a car crash - A car involves a complete stop and releases all of its motion energy without delay in an uncontrolled instant.