posted by gladys on .
a rocket is fire vertically and ascends with constant vertical axceleration of 20 m/s^2 for 1min. its fuel is then all used and it continues to move as a free falling bodyn neglexting rhe variation of g altitude, compute a) the max altitude reached by the rocket and b) the total elapsed time from take off until the rocket touchea the ground
ho = 0.5*a*t^2 = 0.5*20*60^2 = 36,000 m.
Vo = a*t = 20*60 1200 m/s.
a. h. = ho + (V^2-Vo^2)2g
h=36000 + (0-(1200)^2)/-19.6=109,469 m.
b. V = Vo + g*t
Tr = To + (V-Vo)/g=60 + (0-1200)/-9.8 =
h = Vo*t + 0.5g*t^2 = 109,469 m.
0 + 4.9t^2 = 109469
t^2 = 22,341 s
Tf = 150 s. = Fall time.
T = Tr + Tf = 182.4 + 150 = 332 s. =
5.53 min = Time in flight.