help me with this?

Question

A rocket moves upward, starting from rest with an acceleration of 29.8 m/s2 for 4.00 s. It runs out of fuel at the end of the 4.00 s but does not stop. How high does it rise above the ground?
m
I dont know what to do about the part where the fuel stops. Can you please show me what to do

Answer 1

During the 4 seconds it attains a velocity of
v= (29.8 -9.8)*4= 80 m/s 29.8-9.8 mis the net acceleration
After running out of fuel
e=-4.9 t^2+80 t
At maximum height v=0 so -9.8t+80=0 and t = 8.16 s
e max = 326.53 m