Starting from rest, an automobile's velocity $v$ (in $\mathrm{ft} / \mathrm{sec}$ ) is given by $v=\frac{180 t}{2 t+10},$ where $t$ is the time in seconds after the car begins forward motion. Determine the time required for the car to reach a speed of $60 \mathrm{ft} / \mathrm{sec}$ $(\approx 41 \mathrm{mph})$.