physics
posted by frank on .
A model rocket is launched straight upward with an initial speed of 60.0 m/s. It accelerates with a constant upward acceleration of 2.00 m/s2 until its engines stop at an altitude of 130 m.
(a) What is the maximum height reached by the rocket?
m
(b) How long after liftoff does the rocket reach its maximum height?
s
(c) How long is the rocket in the air?
s

I would use energy concepts.
Launch energy: 1/2 m 60^2
engine energy: F*d=ma*d=m*2*130
work done on gravity at the top: mg*h
mg*h=1/2 m 60^2+m*260 solve for h.
For b) find time to the rocket burns out, then add the glide time to the final heights.
c. Add the fall time. 
could you possibly explain A. im still not understanding it.

I solved for h and got 210.2. What am I doing wrong?