# Potential energy

The energy possessed by an object because of its position (in a gravitational or electric field), or its condition (as a stretched or compressed spring, as a chemical reactant, or by having rest mass).

• The potential energy of a stretched spring is —

\begin{align} \label{eq:13201a} PE = \small\frac{1}{2} \normalsize \, k \, u^2 \end{align}

where —

 $$PE$$ = potential energy $$k$$ = spring stiffness $$u$$ = stretch
• The potential energy of a capacitor is —

\begin{align} \label{eq:13202a} PE = \small\frac{1}{2} \normalsize \, (1/C) \, q^2 \end{align}

where —

 $$PE$$ = potential energy $$C$$ = capacitance $$q$$ = charge