Torque is defined as what?

• A. A force that causes rotation
• B. The energy due to rotation
• C. A force that causes translation
• D. Angular momentum

Answer: (A)

Torque measures how strongly a force tends to rotate an object about an axis. It’s not energy (that’s rotational kinetic energy), and it’s not angular momentum (which involves mass distribution and motion). The turning effect depends on the lever arm and how the force is directed: the farther the point of application from the axis and the more perpendicular the force is to the lever arm, the larger the torque.

Mathematically, torque is the cross product of the position vector r (from the axis to where the force is applied) with the force F: τ = r × F, with magnitude τ = r F sin theta. The direction of τ follows the right-hand rule, indicating the axis of rotation. When the force is perpendicular to the lever arm, torque is maximized; when the force is aligned with the lever arm, torque is zero.