Summarizing Work: The Scientific Definition

Summary

• Work is the transfer of energy by a force acting on an object as it is displaced.
• The work \(W\) that a force \(\mathbf{F}\) does on an object is the product of the magnitude \(F\) of the force, times the magnitude \(d\) of the displacement, times the cosine of the angle \(\theta \) between them. In symbols,
  \(W=\text{Fd}\phantom{\rule{0.25em}{0ex}}\text{cos}\phantom{\rule{0.25em}{0ex}}\theta \text{.}\)
• The SI unit for work and energy is the joule (J), where \(1\phantom{\rule{0.25em}{0ex}}\text{J}=1\phantom{\rule{0.25em}{0ex}}\text{N}\cdot \text{m}=\text{1 kg}\cdot {\text{m}}^{2}{\text{/s}}^{2}\).
• The work done by a force is zero if the displacement is either zero or perpendicular to the force.
• The work done is positive if the force and displacement have the same direction, and negative if they have opposite direction.

Glossary

energy

the ability to do work

work

the transfer of energy by a force that causes an object to be displaced; the product of the component of the force in the direction of the displacement and the magnitude of the displacement

joule

SI unit of work and energy, equal to one newton-meter