A torque wrench is a torque tool that we use frequently. N stands for the unit of force, “newton,” and M stands for length, “meter.” Therefore, “NM” stands for “Newton-meter,” which is a unit of torque. Torque is calculated as the product of force and the perpendicular distance from the point of application of the force to the axis of rotation. Torque is primarily used to analyze rotational motion. 100Nm means: a force of 100N is applied at a distance of 1m from the axis of rotation. Alternatively, a 1N force acts at a distance of 100 m; in either case, the total moment is 100 N·m. By definition, 1 N·m is the moment produced by a 1N force acting at a perpendicular distance of 1m from the axis of rotation. In the SI system, force is expressed in newtons (N) rather than kilogram-force (kgf), and length is typically measured in meters (m). Therefore, the unit of torque is newton-meters (N·m). The conversion factors among these units are as follows: 1 kgf·cm = 0.0980665 N·m ≈ 0.1 N·m = 0.01 kgf·m. (1 kilogram-force equals 9.8 newtons, and 1 newton equals 0.102 kilogram-force).
