Difference Between Energy and Work

Energy and work are two of the most prominent characteristics of any matter. Together, they are responsible for the genesis and sustenance of the universe as we know it. Every process that occurs in the universe is because of the transfer of energy and the work that the transferred energy performs on the material. Energy and work can take several forms, but all the processes can be reduced to a thermodynamic process by choosing a suitable system. In fact, we can choose an infinite number of thermodynamic systems in this universe. The laws of thermodynamics are the same for every system. This helps in visualising the system as a gain-loss process of energy in several different forms and helps us to analyze and predict the outcomes of processes.

Energy

Energy is defined as the property of matter through which it does work. If work is not done, and the energy is transferred, then the energy is used to heat the body. Heat can also be considered as cyclic, oscillatory work. But since heat does not translate into a physical change in position of the body, the scientists choose to define it separately. Energy is quantitative. This means we can measure it using devices. The SI unit of energy is Joules (J). One joule is defined as the energy required to move a body by one meter while applying a force of one newton.

One of the fundamental characteristics of energy is that it is conserved, in all the processes of the universe. Energy cannot be created by artificial means nor can it be destroyed. We can only change the form of energy, for example, we can change electrical energy into kinetic energy as in fans. In an isolated system, the total energy of the system before any process is equal to the total energy of the system after the process. This is one of the fundamental laws of the universe and is applicable at both macro and micro levels.

Energy occurs in several forms, like kinetic energy, potential energy, elastic energy etc. Kinetic energy is the energy possessed by an object in motion. Any motion requires the expenditure of energy. If energy is not expended, the object will not move. Potential energy, on the other hand, is defined as the potential of any object to do work under altered circumstances. Potential energy always exists in a force field. A force field is a set of imaginary lines that interact with any object and due to this interaction, the object experiences a force acting on it. Some important force fields which we encounter in our everyday lives are the gravitational field and the electric field. If an object is kept stationary in these force fields by the means of a counteractive force, then the object acquires potential energy. This energy is characteristic of any object present in a force field.

Work

Work is the result of energy transferred to an object due to some force. This force must produce a displacement. If the displacement does not occur, the work done is considered to be zero. This is the biggest differentiating factor between work and energy. In this sense, work can be said to be a form of energy that induces a change in the location of the object. Due to this dependence on the change in the physical location, this form of energy is named ‘work’. Because in our daily lives we often consider work to be done when something is moved. Work is just another manifestation of energy and has the same units. It is also measured in Joules (J).

Work can be negative or positive. Negative work is done when the displacement is in the opposite direction of the force applied, or if the displacement has a component in the opposite direction of the force applied, force and displacement being vector quantities. This happens when a counter force is acting on an object which is stronger than the force which we are considering. In that case, the work done will be positive for the stronger force. The formula for work done can be given by: W = F⋅s

Here,

W is the work done

F is the force vector

s is the displacement vector

Note: Work done is evaluated using dot operation between the two vectors.