The sphere with radius 0.5 whose center has y coordinate = 0.5 and z coordinate = 0.5 is tangent internally to the ellipsoid centered on the origin with principal semi axes of 5, 3 and 2.

How can the x coordinate of the sphere's center be determined?

Imagine a brachistochrone shaped path made of a frictionless flexible metal strip which reacts to the force of a weighty sliding object.

Depending on its flexibility and the object's mass, what would be the strip's initial shape for fastest descent between its top and bottom? How would its shape change during the object's descent?

Perhaps an aircraft emergency escape slide or the fastest path for a slalom skier exemplify this kind of situation.

A flexible rope of constant linear density hangs from one fixed end.

The lower end is pulled aside and then released.

The rope swings back and forth with a whip-like action.

What equation of motion can be used to animate this action in Maple?

I cannot find any references through Google to the appropriate math. 

Please explain the logic used to construct the plot below.

plots:-implicitplot(r >= cos(theta), r = 0 .. 1/3, theta = 0 .. 2*Pi, filledregions, coords = polar, numpoints = 5000, scaling = constrained)

The help page for dsolve,numeric,events says that "A call to a procedure-form dsolve numeric procedure" can return the time that one or more events fired by coding the eventfire option.

I do not know how to code for this.

Please provide a simple example of a procedure-form dsolve numeric with an event that exhibits this feature.