What is a torque wrench used to measure?

A torque wrench is specifically designed to measure the tightness or torque applied to a fastener, such as a bolt or nut. Torque is a measure of rotational force, and by using a torque wrench, one can ensure that a fastener is tightened to a specified level without exceeding it, which could strip the threads or damage the component being fastened.

This precise measurement is critical in engineering and mechanical applications where certain components must be secured with a specific amount of force to guarantee proper functioning and safety. The other options, while related to fasteners in some way, do not pertain to the primary purpose of a torque wrench. For example, measuring the length or weight of a fastener does not relate to how tightly it is secured, nor does measuring the angle, which could pertain more to the position rather than the torque.