Suppose one ramp is a straight shot from A to B (where B is lower than
point A but not directly below it). There are other shape ramps from A to B
that will take the same time of descent (ignoring drag). In particular,
suppose we want a smooth ramp. (No cusp such as Donald's two straight ramps
connected together.) Further suppose we require that the ramp can be
described by a function such that point B can be moved around arbitrarily
and still give a tie with the straight ramp.