Bill Potts wrote in USMA 10202:
>Joe Reid wrote:
>> A vector (or its reciprocal) times a scalar is still a vector. With
>> torque, the vector is the axis of rotation.
>
>As a vector requires both direction and magnitude, how can an axis be a
>vector?
>
>Bill Potts, CMS
>San Jose, CA
>http://metric1.org [SI Navigator]
The usual practice is to use the right-hand rule to determine the direction
of the vector representing the rotation. Consider the z-axis to be the
axis of rotation and the rotation to be such that the x-axis moves toward
the y-axis. Then if the y-axis is considered to extend behind the x-z
plane, the system is right-handed. If the y-axis is considered to extend
in front of the x-z plane, the system is left-handed.
I am sorry for this convoluted explanation. If I had you with me in the
same room I could do better. In short, the direction of the vector
representing the axis of rotataion is determined by the direction of
rotation according to the convention used by the mathematician.
