In an oscillatory flow with flow velocity , the Morison equation gives the inline force parallel to the flow direction:
where
*  is the total inline force on the object,
*  is the flow acceleration, i.e. the time derivative of the flow velocity 
* the inertia force , is the sum of the Froude–Krylov force  and the hydrodynamic mass force 
* the drag force  according to the drag equation,
*  is the inertia coefficient, and  the added mass coefficient,
* A is a reference area, e.g. the cross-sectional area of the body perpendicular to the flow direction,
* V is volume of the body.
For instance for a circular cylinder of diameter D in oscillatory flow, the reference area per unit cylinder length is  and the cylinder volume per unit cylinder length is . As a result,  is the total force per unit cylinder length:
Besides the inline force, there are also oscillatory lift forces perpendicular to the flow direction, due to vortex shedding. These are not covered by the Morison equation, which is only for the inline forces.