system
Given the following post, respond as if you're commenting on Reddit:
human
Why is torque a vector? Right hand rule is a bit arbitrary isn't it? What does the direction of the torque vector signify?
gpt
Torque causes an object to rotate, and rotation in 3 dimensions is determined by an axis, the direction of rotation about that axis, and an angle. The torque vector direction determines the axis and the direction of rotation about that axis. (Since we are talking about continuous rotations, the angle part isn't really given by anything, but the magnitude of the torque is used to determine the rate of rotation.) If you point your right hand thumb along the direction of the torque vector, then your fingers will curl in the direction of the rotation induced by that torque.