What is the S.I. unit of work?

Concept

Work is defined in mechanics as the product of force and the displacement produced in the direction of that force (W = F × d). Because it is a form of energy transfer, work shares its unit with energy.

Application

Substituting base SI units into W = F × d: force is measured in newton (N) and displacement in metre (m), so work is measured in newton-metre (N·m). This combined unit is given the special name joule (J): 1 J = 1 N·m = 1 kg·m²·s⁻².

Cross-check / Contrast

• Metre measures length or displacement alone, not a force-times-distance quantity.

• Newton measures force alone, the cause of motion rather than the energy transferred.

• Second measures time, an independent base quantity unrelated to work.

• Joule is the only choice that equals newton × metre, matching the definition W = F × d.