A rocket engine can accelerate a rocket launched from rest vertically up with an acceleration of 20.0

Question:

A rocket engine can accelerate a rocket launched from rest vertically up with an acceleration of 20.0 m/s2.
However, after 50.0 s of flight the engine fails.
(a) What is the rocket's altitude when the engine fails?
(b) When does it reach its maximum height?
(c) What is the maximum height reached?
(d) What is the velocity of the rocket just before it hits the ground?