One animal $A$ can run $100$ km/h and another animal $B$ can run $85$ km/h. Suppose the slower animal $B$ starts running $25$ meters ahead of the faster animal $A$ in a direction.
How can I calculate the time elapsed before the faster animal $A$ catches the slower animal $B$?
My question: It seems I should just assume constant velocity (is it the same as $a = 0$?), but the animals will have different velocity on take off compared to when they hit their top speed, so isn't it wrong to just assume $a = 0$? But how can I else solve this?