**Solution :**

In question it is given that,

Initial speed, u = 20 km/h

= 20 × 1000m / 60 ×60s

= 5.55 m/s

Final speed, v = 60km/h

= 60 × 1000m/60 ×60 s

= 16.66 m/s

Acceleration, a =? ( To be calculated)

time, t = 6s

** v = u+ at**

16.66 = 5.55 + a × 6

6 a = 16.66 - 5.55

6 a = 11.11

a = 11.11/6

a = **1.85 m/s**^{2}

Thus the acceleration is 1.85 m/s^{2}.