1. The problem statement, all variables and given/known data During a short interval of time, the velocity v in m/s of an automobile is given by v=at^2 + bt^3 where the time is t in seconds. The units of a and b are... 2. Relevant equations 3. The attempt at a solution Alright, here's the thing. A friend gave me some old physics tests, I'm taking it in the fall and familiarizing. I don't know how to do it mathematically. I tried just "plugging in" the units to see if it works out (it's multiple choice here) but I want a way to do it mathematically. Someone, just give me a nudge in the right direction so I can attempt here if you'd be so kind. I don't want the answer, or even too big of a hint.