12.6

A 0.5-oz model rocket is launched vertically from rest at time t=0 with a constant

thrust of 0.9 lb for 0.3 s and no thrust for t> 0.3 s. Neglecting air resistance and the

decrease in mass of the rocket, determine (a) the maximum height h reached by the

rocket, (b) the time required to reach this maximum height.

h