Final answer:
The magnitude of the total initial velocity of the rocket is 9.82 m/s.
Step-by-step explanation:
The magnitude of the total initial velocity of the rocket can be determined by using the kinematic equation:
v0 = v - a * t
where v0 is the initial velocity, v is the final velocity (which is 0 since the rocket lands), a is the acceleration, and t is the time. Rearranging the equation, we have:
v0 = a * t
Substituting the given values, the magnitude of the total initial velocity of the rocket is:
v0 = 54m / 5.5s
v0 = 9.82m/s