A ramp is described by the function y = e^(-x) ; x ≥ 0. For positive times, a disk of radius a rolls without slipping down this ramp. It does so in such a way that the point of contact, denoted by vectorC(t) is parameterized by ‹t, e^(-t)›. Find vector r(t), the position of the center of the disk. Then compute the velocity and the speed of the center.