posted by anonymous .
A rocket is launched straight up with a constant acceleration. Three seconds after lift off, a small part of the rocket falls off the side. The small part hits the ground 7 seconds later. Ignoring air resistance, what was the acceleration of the rocket?
Initial velocity of fragment, at release
Vo = 3 a
Height where fragment is released:
H = (a/2)t^2 = (9/2)a
Since Time to reach ground = 7s:
y(t=7) = H +Vo*7 -(g/2)*49 = 0
(9/2)a + 21a -24.5g = 0
a = (24.5/25.5) g = 9.4 m/s^2