Answer: Alison by 5.1 seconds
Step-by-step explanation: a → cte
Alison 1/9 in 5 sec
Kevin 1/5 in 9 sec
Lenght of the race = x
Alison: x/9 in 5 sec
Kevin: x/5 in 5 sec
They began from the same point: Si = 0
They were not moving when it started: Vi = 0
S = at²/2
Alison: x/9 = a1.5²/2 → a1 = 2x/225
Kevin: x/5 = a2.9²/2 → a2 = 2x/405
Considering the whole distance
Alison: x = a1.t²/2 → x = 2x.t²/225.2 → t² = 225 → t = 15
Kevin: x = a2.t²/2 → x = 2x.t²/405.2 → t² = 405 → t = 20,1
20,1 - 15 = 5,1 s
