1. The problem statement, all variables and given/known data A motorcyclist is travelling at 15.0m/s [forward] and applies brakes. The motorcycle slows down at 5.0m/s [backward]. a) Determine the motorcycle's breaking distance [ans:23 m [forward]] Given: Vinitial: 15.0m/s [forward] a: 5.0m/s^2 [backward] Vfinal: 0 m/s [forward] 2. Relevant equations d= vi(T) + 1/2a(T^2) >>> vector equation vf = vi +aT >>>> vector equation 3. The attempt at a solution 1) Find time for breaking distance vf = vi + aT 0 = vi - aT (making acceleration negative so that it's vector is forward) 0 = 15 - 5T -15/-5 =T 3 = T 2) Finding breaking distance d= vi(T) + 1/2a(T^2) d= vi(T) - 1/2a(T^2) (acceleration made forward by making it negative) d = 15(3) - 2.5(9) d = 75 - 22.5 d = 52.5 m Therefore the braking distance is 52.5 m but the answer is 23m which I think came by ignoring initial velocity but it doesn't make any sense to me why they ignore initial velocity so kindly explain that to me. The picture i uploaded explains why i think initial velocity must be considered.