1. The problem statement, all variables and given/known data A simple model for a person running the 100 m dash is to assume the sprinter runs with a constant acceleration until reaching top speed, then maintains that speed through the finish line. If a sprinter reaches his top speed of 11.2 m/s in 2.14 s, what will be his total time? 2. Relevant equations Xf = Xi + ((Vx)i)(Delta T) + .5(Ax)(Delta T)^2 ((Vx)f)^2 = ((Vx)i)^2 + 2(Ax)(Delta X) 3. The attempt at a solution Ok so I need a second opinion to know if I've done this correctly or not. I have the text book answer but I don't know if its correct or not since I'm not getting the same answer. I start out by finding the acceleration while the runner gets up to speed. 11.2 m/s / 2.14 = 5.23 m/s^2 Using the info given I try and find the distance covered: 11.2^2 = 0^2 + 2(5.23)(Delta X) Delta X = 125.44/10.46 = 11.99 m I then find the time taken to cover the distance: 11.9 = .5(5.23)(Delta T)^2 (Delta T)^2 = 11.9/2.615 = 4.585 Delta T = 2.14 s OK so now.... 100 m - 11.99m = 88.01m I then find the time it takes to travel this distance. 88.01 = .5(5.23)(delta T)^2 (delta T)^2 = 33.65 delta T= 5.80 sec so I add the two times 5.80 sec + 2.14 sec = 7.94 sec Am I doing this correctly? My text book is showing me the time as being 10 seconds but I don't see any other way of finding this answer. Any help is appreciated! Thanks!