Two drivers, Alison and Kevin, are participating in a race. Beginning from a standing start, they each proceed with a constant acceleration. Alison covers the last one ninth of the distance in 5 seconds, whereas Kevin covers the last one fifth of the distance in 9 seconds. Who wins and by how much time?
Accepted Solution
A:
Answer: Alison by 5.1 secondsStep-by-step explanation: a → cteAlison 1/9 in 5 secKevin 1/5 in 9 secLenght of the race = xAlison: x/9 in 5 secKevin: x/5 in 5 secThey began from the same point: Si = 0They were not moving when it started: Vi = 0S = at²/2Alison: x/9 = a1.5²/2 → a1 = 2x/225Kevin: x/5 = a2.9²/2 → a2 = 2x/405Considering the whole distanceAlison: x = a1.t²/2 → x = 2x.t²/225.2 → t² = 225 → t = 15Kevin: x = a2.t²/2 → x = 2x.t²/405.2 → t² = 405 → t = 20,120,1 - 15 = 5,1 s