Two cars, side by side, start from rest and travel along a straight road. The velocity of car $\mathrm{A}$ is given by $v=f(t)$, and the velocity of car $\mathrm{B}$ is given by $v=$ $g(t)$. The graphs of $f$ and $g$ are shown in the figure below. Are the cars still side by side after $T \mathrm{sec} ?$ If not, which car is ahead of the other? Justify your answer.