Question

what are the si units of torque? check all that apply n·m kg·m²/s² n·s kg·m/s²

Explanation:

Torque ($\tau$) is force ($F$) times lever arm distance ($r$), so $\tau = F\times r$. The SI unit of force is newton ($\mathrm{N}$), and distance is meter ($\mathrm{m}$), so $\mathrm{N\cdot m}$ is a unit. Since $\mathrm{N}=\mathrm{kg\cdot m/s^2}$, substituting gives $\mathrm{N\cdot m}=\mathrm{kg\cdot m^2/s^2}$. $\mathrm{N\cdot s}$ is for impulse, and $\mathrm{kg\cdot m/s^2}$ is just $\mathrm{N}$, not torque's unit.

Answer:

A. $\boldsymbol{\mathrm{N\cdot m}}$, B. $\boldsymbol{\mathrm{kg\cdot m^2/s^2}}$