Rocket Launch Question: Calculating Height After 1.5s with Given Mass and Force

[PhysicsTurkey]

Homework Statement

A rocket of mass 0.5kg is shot vertically and burns for 1.5s, providing a constant force of 22N.


After 1.5s what is the height of the rocket above the ground?

The Attempt at a Solution

by taking m*g of the rocket (downwards force) away from the 22N force (upwards).
I figured the resulting upwards force = 17N

unsure how i use this to get the maximum height though

 

[rock.freak667]

Start with a free body diagram. What are the forces acting on the body? What is the resultant of these forces?