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Difference Between Power and Energy

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Last updated date: 04th Mar 2024
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Meaning and Difference Between Power and Energy



Energy and power are two terms that people often use interchangeably in daily life. However, when dealing with Physics, both of these differ in definition, scope and many other factors. Thus, understanding the difference between power and energy is crucial.


However, before proceeding to a detailed power vs energy comparison, let us learn a bit more about these two terms.


What is Power?

Power is defined as the rate at which a specific work is done and for which energy is transmitted. In essence, it refers to the consumption of energy per unit time.


Any object that transfers higher energy in a limited time can be termed to possess greater power. The SI unit of power is Watts, which is Joule/second.


Example of Differing Power

Suppose that A,B and C are the three mechanical machines which are equally efficient and are made to work on a particular set. Machine A, B and C  complete the same work in 20 minutes, 30 minutes and 40 minutes respectively.


Here from this example, we can say that machine A possesses more power in comparison to machine B and C as all three machines are having the same efficiency but machine A completes the same work faster than machine B and C.


What is Energy?

Energy refers to an object or an individual’s ability to do work. The amount of time that one can work defines their energy. Therefore, like power, time is a crucial factor when determining energy. In scientific terms, energy is transferred from one object to another. The SI unit of energy is Joules, which can also be expressed as watt-hour.


Energy can be Divided into Several Types, Such as – Heat

  • Potential

  • Kinetic

  • Electric

  • Mechanical

  • Nuclear

  • Light


Before venturing into the difference between power and energy, you should also know that there are only two sources of energy – renewable and non-renewable. Coal and petroleum are non-renewable sources, while wind and water are renewable energy sources.


Example of Energy

For instance, consider a bowler in a bowling alley. The bowling ball rolls toward the standing pins, and transfers its energy into the pins that it hits, thereby sending them flying. The bowling ball, on the other hand, acquires its energy when the bowler throws it on the lane.


To understand the difference between power and energy in physics, consult the table below.

 

What is the Difference Between Energy and Power?

Comparison Basis

Energy 

Power

Definition

Energy is an object’s ability to complete work.

Power refers to the rate at which an object can complete work.

SI Unit

Energy’s SI Unit is Joule.

The SI Unit for power is Watt. 

What it represents

How much work an object or individual can complete.

How fast an object or individual can complete the work.

Applications

Energy is required for all kinds of work, including walking, running, care movement and more.

Power is common in mechanical, heat and electrical applications. 

Symbol

Energy is commonly denoted by  ‘E’, whereas no specific symbol for it.

‘P’ is used to denote power.

Conversion

You can convert energy from one form to another. 

Power cannot be converted.

Storage

One can easily store energy.

Storing power is impossible.


Now you know the difference between power and energy. Take a look at the common formulas for calculating energy and power.


Take a look at the common formulas for calculating energy and power.


Calculating Power

  • General Calculations - Power (P) = Work/time

  • Standard Electric Power Formula - Power = Voltage x Current

  • Electric Power in Resistors = I2R, where ‘I’ is the current and ‘R’ is the resistance.


Calculating Energy

  • Kinetic Energy – K.E =  \[\frac{1}{2}\]mv2, where ‘m’ is the object mass, and ‘v’ is its velocity.

  • Potential Energy – P.E = mgh, where ‘m’ is mass, ‘g’ is the gravitational acceleration and ‘h’ refers to object height.

  • Electric Energy – W = P x t, where ‘P’ is power and ‘t’ is time.

FAQs on Difference Between Power and Energy

1. What is the Difference Between Electric Energy and Electric Power?

Electric energy is generated from potential differences in a circuit, causing current to flow. Electric power is the rate at which electric energy is transferred within a circuit.

2. What is the SI Unit of Power?

The SI unit of power is Watt, which can be defined as Joule/second.

3. How can Power be Stored?

Power cannot be stored for usage later. You can only store energy.

4. What is an example of energy and power?

If we turn on the switch of a lamp, the potential difference in the closed-loop will cause the current to flow through the circuit. The amount of work that is done in the circuit is the energy. Electric energy here is transferred from the power source to the lamp and will be converted into light energy. As we increase the voltage, the amount of work will increase, which will cause more electrons to flow, and this will increase the amount of transferred energy.

5. What is an example of electrical energy? 

If we turn on the switch of a lamp, the potential difference in the closed-loop will cause the current to flow through the circuit. The amount of work that is done in the circuit is the energy. Electric energy here is transferred from the power source to the lamp and will be converted into light energy. As we increase the voltage, the amount of work will increase, which will cause more electrons to flow, and this will increase the amount of transferred energy.