What is the unit of torque primarily used in mechanical applications?

The unit of torque primarily used in mechanical applications is foot-pounds. Torque is a measure of rotational force, and it quantifies how much a force acting on an object causes that object to rotate. In many mechanical and engineering settings, especially in the United States, foot-pounds is the conventional unit for measuring torque.

In practical terms, one foot-pound corresponds to the amount of torque resulting from a one-pound force applied perpendicularly to a lever arm that is one foot long. This makes it intuitive for applications involving mechanical systems, such as engines, where torque needs to be expressed in a familiar and applicable unit to evaluate the performance and capabilities of the engine or other mechanical components.

While Pascals is a unit of pressure, volts represent electrical potential, and cubic inches measures volume, none of these units pertain to the rotational force or torque as foot-pounds do. Thus, foot-pounds stands out as the most relevant unit for torque in mechanical contexts.