Torque is defined as which of the following?

• A. A force that causes rotation
• B. A type of friction
• C. A tool used for fasteners
• D. The energy stored in a rotating system

Answer: (A)

Torque is the tendency of a force to cause rotation around an axis. It comes from how hard the force pushes at a distance from the pivot: torque equals the distance from the axis to where the force is applied times the component of the force perpendicular to that distance. Mathematically, you can think of it as τ = r × F, which simplifies to τ = r F sin(theta). This means the effect is greatest when the force acts at a right angle to the lever arm, giving maximum lever arm length. The direction of the torque follows the right-hand rule, pointing along the rotation axis.

Put simply, using a longer handle or pushing harder in a perpendicular direction makes it easier to rotate something, because you’re producing more torque for the same force. Torque is not a type of friction, not a tool, and not energy stored in a rotating system. The energy involved in rotation is rotational kinetic energy, 1/2 I ω^2, while torque is what drives (or resists) rotation. The units are newton-meters.