**We are given that**

**Case - I:**

when t = 0, u = 0 when t = 8 sec, v = ?

Acceleration (a) = 5 m/s^{2}

∴ v = u + at

= 0 + 5 x 8 = 40 m/s

s = ut + \(\frac{1}{2}\) at^{2}

s = 0 + \(\frac{1}{2}\) x 5 x (8)^{2} = \(\frac{1}{2}\) x 5 x 64 = 160m

**Case-II:** t = 8 sec to t = 12 sec.

Distance = speed x time

= 40 x 4 = 160 m.

So, the total distance travelled

= 160 + 160 = 320 m.