Energy is the capacity of a physical system to perform work. Energy can be converted in various forms but not created or destroyed. The various forms of energy are solar, wind, hydro, nuclear, thermal, sound, chemical etc. There is no absolute measure of energy because energy is defined as the ability to do work on objects. The law of conservation of energy states that the total energy of a system can only change if energy is transferred into or out of the system. The SI unit of energy is the joule (J) or newton-meter (N * m).
We use energy to do work in our day to day life. Energy from the sun gives us light during the day. Energy lights our cities, Energy powers our vehicles, trains and airplanes. Energy warms our homes, plays our music, cooks our food, and gives us pictures on television. Energy powers machinery in factories and tractors on a farm. We can explore the rate at which energy is used: a one-minute charge of the battery via solar cell will run a flashlight for several seconds but will run a clock for a comparatively longer time. Everything we do is connected to energy in one form or another. It’s easy to make energy conservation part of your daily existence to avoid a serious crisis in the coming decades.