Unit of Work - Definition, Formula, FAQs
Work is one of the most important concepts in Physics that helps us understand how force produces motion. In everyday life, we use the word “work” to describe effort or labour. However, in Physics, work has a specific meaning. Work is said to be done when a force applied on an object causes it to move or change its position. For example, lifting a book, pushing a box, or pulling a cart involves work because a force results in displacement. The amount of work done depends on the magnitude of the force, the distance moved, and the angle between them. Understanding work is essential for studying energy, power, and motion in mechanics.
This Story also Contains
- SI Unit of Work
- Units and Dimensional Formula of Work
- How to Measure Work Done?
- Other Units of Work
- Conversion of Units of Work
SI Unit of Work
The SI unit of work is joule (J). The unit joule is named after the scientist James Prescott Joule in recognition of his contributions to the study of energy and heat.
A joule is defined as the work done when a force of one newton causes a displacement of one metre in the direction of the force. Although newton-metre (N·m) is numerically equal to a joule, it is not preferred for measuring work because the same unit is also used for torque. To avoid confusion, the SI system recommends using only joule (J) for work and energy.
Units and Dimensional Formula of Work
| Quantity | Unit (Force × Distance) | Named Unit |
| SI Unit | N·m | Joule (J) |
| CGS Unit | dyne·cm | Erg |
Dimensional Formula of Work:
$M L^2 T^{-2}$
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How to Measure Work Done?
We regard work as a synonym for effort, labour, exertion or energy invested in our everyday lives. The term work, however, is completely distinct in Physics from all of these terms.
The work carried out is measured as in Joules(J). The work is calculated by multiplying the force by object's displacement.
W = F. S.
Other Units of Work
Apart from the SI unit joule (J), several other units are used to measure work in different systems of measurement and practical applications.
In the CGS system, work is measured in erg. In engineering and commercial fields, larger units such as horsepower-hour and kilowatt-hour (kWh) are commonly used. Units like foot-pound, foot-poundal, and litre-atmosphere are also used in specific contexts.
Since work and heat have the same physical dimensions, heat units such as BTU (British Thermal Unit), therm, and calorie are sometimes used to express work as well.
Conversion of Units of Work
| Unit | Equivalent in Joules (J) |
| 1 erg | 1.0 × 10⁻⁷ J |
| 1 horsepower-hour | 2,684,519.54 J |
| 1 newton-metre | 1 J |
| 1 foot-pound | 1.35582 J |
| 1 kilowatt-hour | 3.6 × 10⁶ J |
| 1 BTU | 1055.06 J |
|
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Frequently Asked Questions (FAQs)
Work unit and its definition. Work unit is Joule. 1 joule is the work done if 1 Newton moves the body in the direction of force by a distance of 1 meter.
The concept of work carried out in W equates, mathematically, to force f times the distance (d), which is W = f. d, and, if it is applied in angle θ − due to the shift, then work done in W = f.dcos θ
The work being done is minimum as COS 180 is equal to negative one when the force is applied to one direction, while the body's displacement is to the opposite end. This is the least work possible and maximum work is done when the force and displacement is in the same direction.
Work is done by moving the object by a force applied to the object. The work is determined by multiplying the force by the movement quantity of the item (W=F*d). There is 30 n-m of work by a force of 10 newtons moving an object for 3 m.
Work is a quantity scalar which is made up of two quantities of vectors.
