1.  Def: Moment
The measure of the tendency of the force to make
a rigid body rotate about a point or fixed axis.

2.  From the definition of a cross product:
From our diagram, r sin q =d, so
Units: Nm, ft lbs, in lbs
q
q
sin
sin
0
0
FrM
rFM


FdM 0

3.  Remember:
We also know:
Thus,
Resultant moment of a system of forces :
FRM

0
kFjFiFF
kRjRiRR
zyx
zyx
ˆˆˆ
ˆˆˆ




zyx
zyx
FFF
rrr
kji
M
ˆˆˆ
0 

)(0 FRMR

