A model rocket blasts off from the ground, rising straight upward with a constant acceleration that has a magnitude of 92.9 m/s2 for 1.85 seconds, at which point its fuel abruptly runs out. Air resistance has no effect on its flight. What maximum altitude (above the ground) will the rocket reach?

Answer 1

thrust stage
v = a t = 92.9*1.85 = 172 m/s
h = (1/2) a t^2 = (1/2)(92.9)(1.85)^2 = 159 m
coast stage
0 = 172 - 9.81 t
t = 17.5 seconds to stop
h = 159 + 172 t -(1/2)9.81*t^2
h = 159 + 172(17.5) - 4.9(17.5^2)
= 1670 m approximately