a rocket propelled car starts from **rest at x = 0 **and moves in the positive direction of x with constant acceleration **a = 5m/s ^{2} **

**for 8 seconds**until the fuel is exhausted. it then continues with constant velocity.

**what distance does the car cover in 12 seconds?**

Here,

a = 5 ms^{-2}

t_{1} = 8 s

t_{2} = 12 s

u = 0

Distance traversed in 8 s under acceleration

s_{1} = ½at_{1}^{2}

=> s_{1} = ½×5×(8)^{2}

=> s_{1} = 160 m

Final velocity at end of 8 s

v = at

=> v = 5×8 = 40 ms^{-1}

Distance travelled with constant velocity of 40 ms^{-1} will be

s_{2} = v(t_{2} – t_{1})

= 40(12 - 8)

= 160 m

Total distance covered = s_{1} + s_{2}

= 160 + 160

= 320 m

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