**Solution:**

The distance travelled by the rocket during consumption of fuel ( 30 sec.) in which resultant acceleration is vertically upwards i.e 10 m/s^{2} will be

**h = ut + 1/2gt**^{2}

h = 0*30 + 1/2*10*30^{2 }= 4500m --------------------(1)

Velocity will be

**v = u +at**

v = 0 + 10*30 = 300m/s ---------------(2)

As after the fuel is consumed the initial velocity from eqn. (2) is 300 m/s and gravity opposes the motion of rocket, so from 1 st equation of motion time taken by it to reach the maximum height (for which v = 0)

** v = u – gt**

0 = 300 – 10t

t = 30 sec