Dear Kevin,

You wrote:

> In the case of the foot, the inertial dynamic loading is relative small.
>Therefore, a >quasi static analysis can be used. This means that the free
>body is assumed to be in >equilibrium at all times, and the mechanical
>analysis can be performed at any instant >without reference to the
>position velocity or acceleration of the foot at other time >intervals.
>

Bart replies:

Indeed, in free body analyses, it is common practice to neglect the
inertial term (moment of inertia X angular acceleration) in the equations
because the contribution of the forces acting on the segment (GRF ,
intersegmental forces, muscular and ligamentous forces etc.) are most of
the time many times larger. This is called a quasi-static situation: in
theory there is still accelerated/decelerated motion, but it so small that
in practice on can consider the system to be in equilibrium or static.
In the case of the foot, this approach is even more justified as the mass
of the foot and thus also its moment of inertia are rather small, allowing
the non-zero inertial term  in the free body equations  to disappear.
Regards to all,
Bart

*******************************************************************
 Bart Van Gheluwe
Laboratory of Biomechanics
Vrije Universiteit Brussel -Fac. LK
Vakgroep BIOM
Pleinlaan 2, 1050 Brussel, Belgium
Tel.: 02/629.27.33 (31)
Fax: 02/629.27.36
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