Speeding

help with this problem of kinematics? response is fine, but the work is appreciated?

On June 14, 2005, Asafa Powell of Jamaica sets a world record for the 100 m race with a time t = 9.77 s. Assuming that reached its maximum in 3 s, and then maintained that speed until the end, estimate of acceleration during the first 3 s. I have 22.22222 m / s / s, but I know its bad thanks for the help

The answer is 4.03 m / s ^ 2. You has two intervals of 3 and 6.77s for the first interval with an acceleration (a =?): Vf = Vo Vo Use + t * a = 0 and t = 3s Vf = 3 * t * S Use = Vo + 1 / 2 * a * t ^ 2 S1 = 1 / 2 * a * t ^ 2 = 1 / 2 * a * 9 = 4.5 * For the range of seconds at a constant rate: S2 = 6.77 * Vf = 6.77 * 3 * a = 20.31 * Now one of the two intervals: S1 + S2 = 100 4.5 m * a * 20.31 + a = 100 m 24.81 * A = 100 = ma = 100m/24.81 4.0306 m / s ^ 2

Speeding Swede Faces World Record Fine