Question

Compute the magnitude of the moment of the force P about point A

Answer 1

Gives

Point A 

Magnitude of moment of force=P

The moment of a force about a point provides a measure of the tendency for rotation (sometimes called a torque). As shown,

d is the perpendicular distance from point A to the line of action of the force. by using the components of F as shown.

Moment of force =force$\times$ perpendicular distance

$\tau=F\times d$

2-D moment of force

$\tau=\begin{vmatrix} \hat i&\hat j&\hat k\\ F_x & F_y &F_z\\ d_x&d_y&d_z \end{vmatrix}$

$$\tau=\hat i (F_yd_z-F_zd_y)-\hat j(F_xd_z-F_zd_x)+\hat k(F_xd_y-F_yd_x)$$