Finding max height and speed before it hits the ground of a rocket

llach

1. The problem statement, all variables and given/known data

A model rocket initially at rest on the ground is fired vertically upward, and the engine thrust produces a constant acceleration a = 40 m/s2. After running for 2.5 s the engine is cut off and then the rocket is in free fall. (a) Find the maximum height that the rocket reaches. (b) Find the speed of the rocket just before it hits the ground.
Ans: (b) 635 m (c) 112 m/s
Note: The rocket travels with 40 m/s2 acceleration during the first 2.5 s (gravity effect included).


2. Relevant equations



3. The attempt at a solution

rl.bhat

In the relevant equations, can you write the kinematic equations. And using the given data, you can select a proper equation to solve the problem.