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# Unit of work

The SI unit of work is the joule $(\text{J})$. One joule is the work done when a force of $1\text{ N}$ displaces an object by a distance of $1\text{ m}$ in the direction of the force.

In SI base units, the joule can be expressed as $\text{N m}$. That is also the unit of the moment (or turning effect) of a force but moments and and work are very different and should not be confused.

Work done is a scalar quantity and a moment is a vector quantity. Work is always expressed in $\text{J}$ and moments in $\text{N m}$.

The quantities weight and work both have the same symbol ($W$), so it is important not to confuse the two in equations.

The joule is named after the scientist James Prescott Joule. Joule spent a lot of time working on work. He also had an impressive beard.