max height II t= V= y = parachute opens II III t= V= y= float down t= V= y = out of fuel IV t = V= y= t = V = y= ground A model rocket, initially on the ground, is fired vertically upward from rest. Its acceleration for the first four seconds is a(t) = 48t at which time the fuel is exhausted and it becomes a "free falling" body (that is to say, a(t) = -9). Twenty seconds later, the rocket's parachute opens and the downward velocity slows linearly to -32 ft/sec in 8 seconds; the rocket then floats to the ground at that rate. Get the acceleration function for each stage I, II, III, IV, and fill in all the times, velocities, and altitudes