Energy is used by all organisms to survive, grow, reproduce, or carry out any sort of activity. It is converted or transferred to an object to create ‘change’. It is required to carry out even the simplest of tasks, such as picking up a pen.
On the other hand, power refers to the rate at which a certain amount of energy is being used. For example, power measures how fast a pen is being picked up; the faster it is picked up, the more power is used by the person who is applying force.
Energy vs Power
The main difference between energy and power is that energy is a measurable property that makes ‘change’ happen when transmitted or converted, whereas, power is the rate at which energy is used or transferred during a certain period of time. Both of these are important concepts of work.
Comparison Table Between Energy and Power
| Parameters of Comparison | Energy | Power |
| Meaning | Energy is a measurable property that makes ‘change’ happen when transmitted or converted. | Power is the rate at which energy is used or transferred during a certain period of time. |
| Standard unit of measurement | The standard international unit of energy is Joules. | The standard international unit of power is Watts. |
| Symbols | The symbol ‘W’ is used to denote energy. | The symbol ‘P’ is used to denote power. |
| Calculation | Energy is calculated by multiplying power with time {Energy (W) = Power (P) × Time}. | Power is calculated by dividing energy by time {Power (P) = Energy (W) ÷ Time} |
| Storage | It is possible for energy to be stored. | It is not possible for power to be stored. |
| Conversion | It is possible for energy to be converted from one particular form to another. | It is not possible for power to be converted from one form to another. |
| Examples | Energy is required to carry out tasks such as, picking up a pen, throwing a ball, climbing a ladder, etc. | Power refers to at what rate the pen is picked up, the ball is thrown, the ladder is climbed, etc., with respect to time. |
What is Energy?
The word ‘energy’ comes from the Ancient Greek word ‘energeia’, which first appeared in the great philosopher, Aristotle’s work. At that time, the term was more qualitative than quantitative. It had a philosophical context and included broad ideas such as sadness and happiness.
Presently, in physics, energy refers to a measurable property that can be used or converted in order to make ‘change’ happen. This change could be in the form of motion, heat, and so on. All organisms store some form of energy in them which they take from food. This energy is used by them to survive and flourish.
In 1843, James Prescott Joule derived a unit for energy, Joules, which is now the standard international unit. The energy which is used to exert a force of 1 newton while spanning a distance of 1 meter is measured to be 1 joule.
Every object that has some amount of mass stores energy as well. This is in the form of rest energy. Other common forms of energy include potential energy, kinetic energy, elastic energy, chemical energy, thermal energy, and radiant energy.
What is Power?
Power can be defined as the measure of how fast work is done. It is the rate at which energy is used or transferred to an object in order to create change. For example, a certain amount of power is taken in order to exert force while pushing a door.
The standard international unit to measure power is Watts. The power taken to exert 1 joule of energy in 1-second equals to 1 Watt. When more power is used, the work is done in lesser time while less power means that more time has been used.
The correlation of power with time can be understood by their standard equation. Power is calculated by dividing energy by time {Power (P) = Energy (W) ÷ Time}. The definition and equation of power had an important use in the invention of the steam engine during the early 70s in England.
The Scottish inventor, chemist, and mechanical engineering, James Watts, was responsible for coming up with the concept of power. He did this by introducing his Watts steam engine in 1776, which was an upgrade of the previously used Newcomen steam engine.
Main Differences Between Energy and Power
- Energy is a measurable property that can be used or transferred in order to make ‘change’ happen while power is the rate at which this energy is transferred.
- The standard international unit for measuring energy is Joules while the standard international unit for measuring Power is Watts.
- Energy is denoted by the symbol ‘W’ while power is denoted by the symbol ‘P’.
- Energy is calculated by multiplying power with time while power is calculated by dividing energy by time.
- A certain amount of energy is exerted when force is applied to pick up a pen. Meanwhile, the rate at which this energy is exerted refers to power.
- Energy can be stored while power cannot.
- Energy can be converted while power cannot.
Conclusion
Energy and power are concepts that are crucial to the process of ‘work’. Their difference can be understood and remembered by the fact that energy is an amount while power is a rate. Moreover, power is the rate at which energy creates change.
Another way to describe the two is that power is energy per unit of time. While power can be measured in Watts, energy is measured in watts per hour. Apart from physics, both words are used in many different contexts and meanings.
References
- https://eric.ed.gov/?id=EJ349839
- https://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.462.8742&rep=rep1&type=pdf