To find the distance (s) and acceleration (a), we can use the following kinematic equation:

s = u0t + 0.5a*t^2

Given:
u0 = 28.8 km/h = 8 m/s
t = 5 s
u1 = 5, 6, 7 km/h = 1.39, 1.67, 1.94 m/s

First, let's calculate the distance covered by the object:
s = 85 + 0.5a5^2
s = 40 + 2.5a

Now, let's consider the acceleration of the object:
v = u + at (where v=u1 and u=u0)
a = (v - u) / t
a = (1.39 - 8) / 5
a = -6.61 / 5
a = -1.322 m/s^2 (for u1 = 5 km/h)

a = (1.67 - 8) / 5
a = -6.33 / 5
a = -1.266 m/s^2 (for u1 = 6 km/h)

a = (1.94 - 8) / 5
a = -6.06 / 5
a = -1.212 m/s^2 (for u1 = 7 km/h)