Skydiving A skydiver in free fall subject to gravitational acceleration and air resistance has a velocity given by $v(t)=v_{T}\left(\frac{e^{a t}-1}{e^{a t}+1}\right),$ where $v_{T}$ is the terminal velocity and $a>0$ is a physical constant. Find the distance that the skydiver falls after $t$ seconds, which is $d(t)=\int_{0}^{t} v(y) d y$