A joule is the SI unit of energy, defined as the amount of work done when a force of one newton displaces an object by one meter. It is also equivalent to one watt-second.
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A joule can be expressed mathematically as $1 \text{J} = 1 \text{N} \cdot \text{m}$ or $1 \text{J} = 1 \text{kg} \cdot \text{m}^2 / \text{s}^2$.
In physical applications, integrating a force over a distance can calculate the work done in joules.
When dealing with potential energy and kinetic energy problems, results are often given in joules.
The concept of mechanical work in physics is directly tied to the calculation of energy in joules using integrals.
In calculus, computing the area under a curve representing force over distance gives the total work done in joules.
Review Questions
How is one joule defined in terms of newtons and meters?
What integral would you compute to find the total work done by a variable force over a distance?
Why are results from potential energy calculations typically expressed in joules?
Related terms
Newton: The SI unit of force, defined as the amount needed to accelerate a one-kilogram mass by one meter per second squared.
Watt: The SI unit of power, equivalent to one joule per second.
Work: In physics, work is defined as the product of force and displacement. When force is applied along the direction of displacement, it can be calculated using $W = Fd$.