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3.3: Moment of Momentum

In a similar way, if a particle at position \(\textbf{r}\) has linear momentum \( {\bf p } = m {\bf v} \) , its moment of momentum with respect to the origin is the vector \(\textbf{l}\) defined by

\[  \textbf{l} = \textbf{r} \times \textbf{p} \label{eq:3.3.1} \]

and its components are the moments of momentum with respect to the axes. Moment of momentum plays a role in rotational motion analogous to the role played by linear momentum in linear motion, and is also called angular momentum. The dimensions of angular momentum are \( ML^{2}T^{-1} \). Several choices for expressing angular momentum in SI units are possible; the usual choice is J s (joule seconds).