How high will it go? A model rocket burns hard for a second or two, then coasts up against gravity and air until it stops — the apogee. It is real Newtonian flight you can compute before you ever light the fuse. Slide the motor (or tap) from an A to an E.
A model-rocket flight, integrated. Total impulse I (newton-seconds) sets the motor class (A=2.5, B=5, C=10, D=20, E=40 N·s, each double the last). A burn phase applies thrust T over burn time (I = T·t_burn) against weight and quadratic drag ½ρv²C_dA; then a coast phase decelerates under gravity and drag until vertical velocity hits zero — the apogee. The altitude(time) curve is integrated live by semi-implicit Euler. A fail-loud self-check throws unless a larger total impulse yields a higher apogee (monotone).
A point-mass rocket with fixed mass, drag coefficient and a flat thrust curve (real motors have shaped thrust, mass loss, wind, and stability limits); constants are illustrative. The Newtonian integration and the impulse→apogee ordering are exact.