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A rocket is fired straight up and accelerates upward at 24 m/s2 for 12 seconds. The rocket then runs out of fuel and coasts. Ignore any air resistance effects and use 9.8 m/s2 for the local acceleration due to gravity.
a) What is the rocketâ€™s maximum altitude?
b) How long is the rocket in the air, from take off until it hits the ground?
c) If the retarding drag chute fails, what is the rocketâ€™s velocity when it hits the ground?
Answer

physics 
Henry,
a. Vo = at = 24m/s^2 * 12s = 288m/s,
h = (Vf^2  Vo^2) / 2g,
h = (0  (288)^2) / 19.6 = 4232m.
b. t(up) = (Vf  Vo) / g,
t(up) = (0  288) / 9.8 = 29.4s.
t(dn) = t(up) = 29.4s.
T = t(up) + t(dn) = 29.4 + 29.4=58.8s.
= Time in flight.
c. Vf = Vo(up) = 288m/s.