A70.0 kg sprinter starts a race with an acceleration of 2.00 m/s2. if the sprinter accelerates at that rate for 29 m, and then maintains that velocity for the remainder of the 100 m dash, what will be his time (in s) for the race?

t = 12.82s

Explanation:

F = m×a

  = (70)×(2)

  = 140 N

during the acceleration, the sprinter cover d = 29 m with time:

d = 1/2×at

29 = 1/2×(2)×t^2

t^2 = 29s

t = 5.39s

and attains the velocity of:

v = a×t

  = 2×5.39

  = 10.77 m/s

Then,to cover the last x = 80 m with a speed of 10.77 m/s in time:

t = x/v

 = 80/10.77

 = 7.43s

Therefore, it will take the sprinter 7.43 + 5.39 = 12.82s

okay i have so many questions. but the big one here is: um wt..f is this mess? ?