how many seconds would it takes a boat to accelerate from 13m/s to 20m/s over a distance of 1.25 km ?

Answer 1

V^2 = Vo^2 + 2a*d = 20^2
13^2 + 2a*1250 = 400
2500a = 400-169 = 231
a = 0.0924 m/s^2

t = (V-Vo)/a = (20-13)/0.0924 = 75.8 s.