Torque, or the moment of a force, is the ability of a force to rotate a body about a point or an axis that is not in the line of action of the force. It is a vector quantity. Consider an example of a flywheel, where a force is applied to rotate the flywheel about point O. Here, the moment arm is the perpendicular distance from point O to the line of action of the force. The magnitude of the force is multiplied by the moment arm to obtain the magnitude of the moment. So, the unit for the moment of a force is newton-meter. Its magnitude is maximum when the applied force is tangential to the flywheel. The right-hand rule is used to determine the direction of the moment. If the curled fingers represent the rotation caused by the moment, then the thumb represents the direction of the moment. Conventionally, the positive moment denotes the counterclockwise rotation, while the negative sign denotes the clockwise rotation of the flywheel.