physic
posted by O.albania .
A rocket accelerates straight up from rest for 20 seconds with an acceleration of 8 m/s2. After 20 seconds the rocket motor shuts off and the rocket continues to coast upwards. How high does the rocket go in meters?

During fuel burn,
v = at = 8*20 = 160
after that, the height
h = 160t  4.9t^2
the vertex of the parabola occurs when t = 160/9.8 = 16.32 seconds
At that point, h(t) = 1306.12 m