What is Energy?
Energy is defined as the capacity to do the work. Energy is invisible, but work is not. So when we see work being done, we conclude the energy must be present for that work to be done. Usually, an object ( or even a liquid or gas) generates the force that does the job. Therefore energy is associated with the thing ( or liquid or gas) that causes the point which does the work. For example, when water is boiled, and steam is released, the moisture can generate power that can move a whole train. We can, therefore, conclude that the stream must have had energy since it has done work. When a leaf sways due to the wind, the wind must have had the energy to do the job. If X units of work are done, we assume that the same number of units of energy must have been used up, and the energy within the object or agency doing the work must have been reduced by the same quantity.
SI unit of Energy?
The SI unit for measuring energy is the same as measuring work, which is the joule. The larger units for measuring power are also correspondingly kilojoule and megajoule.
The functional unit of measuring electrical energy is the kilowatt-hour which is also colloquially referred to as "unit." One kilowatt-hour is the energy consumed at the rate of one kilowatt for one hour. This is equivalent to 3600000J [1000W x 3600s =3600000J = 3.6x106 J].
Different forms of Energy
Anything that can do work contains energy. We understand that heat can do work from the example of the steam engine. Therefore, heat is a form of energy. Electricity can produce heat when it is passed through a resistance.
Electricity is also used to run fans and lights. Therefore, electricity must also be a form of energy. Wind can be used to do work, and so it is also a form of energy, and all of them can perform some work.
Some necessary forms of energy are chemical energy, light energy, nuclear energy, sound energy, and mechanical energy. We shall discuss mechanical energy in a little more detail later in this chapter.
Obtaining Energy
In the preceding section, we spoke about how energy gets lost by steam ( or any other object) while going to work. The question that naturally arises is: " Where does an object get its energy from?" The answer to this question leads us to one of the essential laws in mechanics after Newton's Laws.
An object can acquire energy in two different ways. It can get power when,
- Energy is some other form that is converted and added to the energy that the object already possesses. Energy can never be created.
- Work is done.
Law of Conservation of Energy
The Law of conservation of energy states that:
'Energy can neither be created nor destroyed. It can only be changed from one form to another.
A car engine burns fuel, converting the fuel's chemical energy into heat energy, which in turn is converted into mechanical energy to make the car move. Windmills transform wind energy into mechanical energy, which can turn a turbine to produce electricity. The electrical power can be changed into light energy in a bub. It can also be converted into mechanical energy, turn a fan, or transformed into heat energy to cook food. The cooking of food itself is a chemical reaction that can go backward on the energy transformation chain. Wind energy comes from the heat energy flowing from the sun, and the sun's energy itself comes from nuclear relations within the sun.
You must be logged in to post a comment.