• DDistanceDT[point1, point2] returns the time derivative of the absolute distance between the two points.
• DDistanceDT[point1, point2] is equivalent to Dt[Distance[point1, point2], T], except that the local coordinates of the points are assumed to have no implicit dependence on any Mech system variables.
• See also: Distance, D2DistanceDT2.
Load the Modeler2D package and define a simple model.
If the distance between two points is calculated simply as the magnitude of the vector between the two points, then some obvious simplifications are missed, like the fact that the two points lie on the same body.
Distance checks for such simplifications.
DDistanceDT assumes that c is constant in the following, while direct differentiation with Dt cannot.
Similarly, D2DistanceDT2 assumes that local point coordinates are constant.