Hi Folks: I am puzzled by this problem; there must be something wrong but I can't see what... 1. The problem statement: "A runner enters the last 200 m of a race running 6 m/s. She accelerates at 0.2 m/s2 &crosses the finish line at 10 m/s. What is her time for the last 200 m?" 2. Relevant equations: "(HINT: use V-V0=a*t to find time. Then use X = Vo*t + 0.5*a*t^2 to get t)." 3. The attempt at a solution: V-V0=a*t --> 10-6=0.2*t --> 4=0.2*t --> t=4÷0.2=20s. That self-checks: V-V0=a*t --> V-6=0.2*20 --> V=4+6=10m/s But the second part is more problematic. X is the distance; I plug in the 20s from the first equation. X = Vo*t + 0.5*a*t^2 X = 6*20 +0.5*0.2*(20^2) X = 120+0.01*400 = 120+40 = 160...instead of 200 as it should be! It's also possible to put X=200 from the problem, and solve a quadratic for t, but that is a big pain in the rear. Anyway, I am really wondering what silly step I am missing that part 2 gives me 160 instead of 200!?!?!