Work

Definition

Work is the energy transferred to or from an object via a force acting upon it over a displacement. In physics, work is mathematically expressed as $W = F \cdot d \cdot \cos(\theta)$, where $F$ is the force, $d$ is the displacement, and $\theta$ is the angle between them.

5 Must Know Facts For Your Next Test

1. The SI unit of work is the joule (J), which is equivalent to one newton-meter (N·m).
2. Work can be positive or negative depending on the direction of the force relative to the displacement.
3. If there is no displacement, no work is done regardless of the amount of force applied.
4. In thermodynamics, work done by or on a system can change its internal energy.
5. For gases in a piston, work can be calculated using $W = -P \Delta V$, where $P$ is pressure and $\Delta V$ is the change in volume.

Review Questions

• What are the conditions under which no work is done?
• How does work relate to changes in internal energy in thermodynamic systems?
• Explain how to calculate work for a gas in a piston undergoing expansion.

Related terms

Heat: The transfer of thermal energy between systems due to temperature difference.

Internal Energy: The total energy contained within a thermodynamic system due to both kinetic and potential energies of its particles.

First Law of Thermodynamics: \(\Delta U = Q - W\), which states that the change in internal energy ($\Delta U$) of a system equals heat added ($Q$) minus work done by the system ($W$).