The shear flow formula provides a means for computing the amount of force that must be transmitted between connected parts in a flexural member:

where q = shear flow (force per unit length of beam span), V = shear force, and I = moment of inertia.

Q is a section property that is used in the calculation of beam shear flow. Q is defined as the first moment of the cross-sectional area of the connected part about the centroidal axis for the complete cross section.