A 0.2-lb model rocket is launched vertically from rest at time t=0 with a constant thrust of 2 lb for one second and no thrust for t > 1 sec. Neglecting air resistance and the decrease in mass of the rocket, determine (a) the maximum height h reached by the rocket, (b) the time required to reach this maximum height.
Weight = 0.2 lb, Thrust force = 2 lb/sec
(1) FT-mg = ma
W = mg
The Attempt at a Solution
I solved for the mass of the rocket by using m = W/g, where W = 0.2 lb and g = 32.2 ft/sec^2. Then I solved for 'a' in Equation (1) to get 289.8 ft/sec^2. To find the maximum height, I used y = y0 + v0t + 1/2*(at)^2. Since v0 = 0, I got y-y0 = 144.9 ft. (I think the correct answer is supposed to be 1449 ft - looks like I am off by a factor of 10).
Also, for the second part, how do you find the time?
I think I'm missing something here...