A toy rocket, launched from the ground, rises

vertically with an acceleration of 28 m/s2 for
9.5 s until its motor stops.
Disregarding any air resistance, what max-
imum height above the ground will the rocket
achieve? The acceleration of gravity is
9.8 m/s2 .
Answer in units of km

2 answers

Vo = a*t = 28 * 9.5 = 266 m/s.

ho = 0.5a*t^2 = 14*9.5^2 = 1264 m.

h = ho + (V^2-Vo^2)/2g
h = 1264 + (0-(266^2)/-19.6 = 4874 m. =
4.874 km.
i tried it but gives me an incorrect answer