Question

Express the moment of the couple acting on the rod in cartesian vector form. What is the magnitude of the couple moment?

Answer 1

We are given with the vectors
-F = 4i - 3j + 4k
and
F = -4i + 3j - 4k
To get the moment, we determine the cross product between the two vectors
-F x F = 0i + 0j + 0k
The magnitude is 0 but this is if the pivot is the origin. In the couple, the magnitude is 4.