Negosentro | Work, Energy and Power-Learning Outcomes | In the early days of school work, energy and power were the most important terminologies in physics. Work and energy are both interrelated to each other.
Work, Energy and Power definitions are to be learnt for basic understanding of this article.
- Work is the displacement of a body when a force is applied to the body.
- The change in kinetic energy is equal to the amount of work done by all the forces. The ability to carry out the work is called Energy. There are different forms of energy like nuclear energy, chemical energy, thermal energy, electrical energy etc.
- The work done per unit of time is the Power. This article gives detailed information about work, energy and power, which is important in acquiring knowledge.
Definition of Work, Energy and Power
What is Work?
In physics, work can be defined as a transfer of energy to the body. If one body gives energy to a second body, then the first body is doing work on the second body. Also, work is defined as the application of a force on an object over a distance.
The work is said to be done when a force is exerted on an object, and there is the object’s displacement in the direction of the force. Work has no direction but has only magnitude. So, work is a scalar quantity.
Examples of work are: lifting a weight from the ground surface and putting it on a shelf, a weightlifter lifting a barbell above his head, a cow pulling a plough in the field etc.
Formula of Work
The work done by a force is equal to the product of the component of the force in the direction of displacement and magnitude of the displacement.
W=(F cosƟ)*d=F*d
From the work equation, we can summarize that no work is done if:
- The displacement is zero
- The force applied is zero
- The force and displacement are perpendiculars mutually to each other.
When a motion is produced in an object, then you say work is done. When a man tries to push a wall, but the wall has no motion. Then the work done is zero as there is no displacement in the wall. But he loses energy and feels tired from pushing the wall by stretching his muscles. So we can say that work is not done when a force is applied to an object.
When the force applied can change the direction of an object, then only the work is done.
Unit of Work
The SI unit of work is Joule(J).
1J=1Nm
What is Energy?
The ability to perform work is called energy. Energy is the important thing for work to be done. The energy is obtained from food for the work done by living beings; when machines do work, the energy is obtained from fuel or electricity. In many things, energy is found, and there are different types of energy.
Different types of energy are chemical, magnetic, thermal, heat, nuclear, gravitational, mechanical, elastic energy etc.
Law of conservation of energy
Energy can neither be created nor destroyed but can only be transformed from one form to another. All the different forms of energy follow this law.
There are two important types of energy: Kinetic and Potential energy. Kinetic energy is defined as the energy that a body possesses due to its movement. The energy stored in an object is defined as Potential energy, and the amount of work done measures it.
Joules(J) is the SI unit of work. The energy has only magnitude and no direction, and it is a scalar quantity.
What is Power?
Power is a physical concept that has different meanings depending on the available information and the context used. The rate of doing work is defined as power, and also it is defined as the amount of energy consumed per unit of time.
The formula for power is given below, and it is calculated as the ratio of work done to the time taken.
P=W/t
The power is a scalar quantity as it does not have any direction. The SI unit of power is Joules per second(J/s), named Watt. So the term watt is defined as the power required to do one joule of work in one second.
Differences
The differences between work, energy and power are listed in the following tables:
Difference between work and energy:
| Work | Energy |
| The work is an action done on an object causing the displacement. | The ability to carry out the work is called energy. |
| Work =Force*Displacement | There are various equations depending on the forms of energy |
| If the applied force is in the same or the opposite direction of the displacement, then the work is positive or negative respectively. | As Energy is a scalar quantity, there is no direction component. |
Difference between work and power:
| Work | Power |
| Work done by a force is equal to the product of force and displacement in the direction of a force. | The rate at which the energy is converted or transferred is called power. |
| Work done is not dependent on the time factor. | Power depends on the time at which work is done. |
| Joule is the SI unit. | SI unit is Watt |
| The formula for Work done=Force*displacement | The formula for Power=Work/Time taken |
Difference between energy and power:
| Energy | Power |
| The ability to perform the work is called energy. | The rate at which the energy is converted or transferred is called power. |
| The SI unit is Joule | The SI unit is Watt |
| Energy can be transformed into other different forms. | Power cannot be changed to other forms. |
| Energy can be stored | Power cannot be stored. |
Conclusion
We can conclude that for the work to be done, energy is required, the amount of work done in a given unit of time is called the power, and the work is any action causing the change in an object position. So the fundamental concepts of physics work, energy and power are all interrelated to each other.
FAQs
- What is the unit of work?
The SI unit of work is Joule.
- Is power a scalar quantity?
Yes, power is a scalar quantity.
- What is the unit of energy and power?
The SI units of energy and power are Joule and Watt, respectively.
