What is the SI unit of torque?

The SI unit of torque is the Newton meter, which is derived from force and distance. Torque, which is a measure of the rotational force applied to an object, can be calculated as the product of the force exerted (in Newtons) and the distance from the pivot point to the line of action of the force (in meters). Therefore, when you multiply Newtons (the unit of force) by meters (the unit of distance), you get Newton meters. This makes it a suitable unit for measuring the effectiveness of a force applied at a distance from a pivot point, which is essential in fields such as physics, engineering, and mechanics.

The other options do not accurately represent the unit of torque. The Newton measures force, while the Joule measures energy (and is equivalent to a Newton meter, but is not commonly used to express torque directly). The Pound is a unit of weight in the imperial system, which is not applicable in the context of SI units. Thus, Newton meter stands out as the correct choice for describing torque in the International System of Units.