Okay, first post... don't be too hard on me! Just got around to joining the forum even though i have been browsing for quite some time. 1. The problem statement, all variables and given/known data A sprinter can accelerate with constant acceleration for 3.30 before reaching top speed. He can run the 100-meter dash in 10 s. What is his speed as he crosses the finish line? 2. Relevant equations Kinematic Equations Sf = Si + Vi[tex]\Delta[/tex]t + .5a[tex]\Delta[/tex]t^2 Vf^2 = Vi^2 + 2a[tex]\Delta[/tex]s Vf = Vi + a[tex]\Delta[/tex]t 3. The attempt at a solution I have tried this problem using two methods that haven't gotten me very far. First I tried to look at the problem in two different steps: the first 3.30s and then the last 7.70s. I solved one equation for acceleration using the first interval: a =Vf1/3.30s But I realized I can't substitute this into equations referring to the second time interval. My second attempt I tried to look at the overall. I noted that the average velocity must be 10m/s over the whole 10s interval, but this attempt pretty much fizzled out at that point. This is an extra credit problem for my class, but I really want to go that extra mile (or 100m as the case may be). Please lend this noob a hand!