Energy is defined as the ability to do work. In short, energy is required for you to accomplish some work. For example, for 100 joules of work to be done, 100 joules of energy is spent. Energy is something that is possessed by objects. The energy from one object can either be transformed from one object to another or converted from one form of energy to another. However, energy can neither be created nor destroyed.
The SI units of energy is Joules. One joule is defined as the energy transferred to an object by the mechanical work of moving the object through a distance of one meter against a force of one newton.
There are various forms of energy which include: kinetic energy of a moving object, radiant energy carried by electromagnetic waves such as light waves, thermal energy, elastic energy stored by stretching solid objects like springs, chemical energy released during chemical reactions, and potential energy that is stored by an object’s position in a force field. It is not possible to create any of these forms of energy. But one form can be converted to another form if necessary.
In simple terms, it states that for a closed system (a system with no external sources of energy or sinks of energy), the system’s energy is constant unless energy is transferred in or out of the system by mechanical work or heat and that no energy is lost in the transfer. This is the law that shows that energy cannot be created or destroyed. For college students, this law is taught in detail during H2 Physics tuition classes since it is a tested concept.
Second Law of Thermodynamics
It states that all systems doing work always lose some energy in form of heat. Therefore there is a limit to the amount of energy needed to do work by a heating process. This limit is referred to as the available energy. The total sum of all the energies within a system is calculated by adding up all the forms of energy within the system under consideration.
Examples of Energy Transformations
1. Generating electric energy using a steam engine: First, there is thermal energy in the steam that is transferred to a steam turbine which then converts the thermal energy into electrical energy.
2. Lifting an object: When the object is lifted, gravitational potential energy is stored in the object. Then if the object happens to fall from its height, the potential energy that was stored in the object is transformed into kinetic energy as the object falls and to heat upon impact with the ground.