Answer:
a) F = 88.2 10⁶ N and b) t = 8.44 s
Explanation:
With Newton's second law we can work the first part
F = m a
a = 4g
F = 2.25 10⁶ 4 g
F = 2.25 10⁶ 4 9.8
F = 88.2 10⁶ N
This is the force that is applied to the rocket, but by action and reaction it is also the force that the rocket applies to all its occupants
To calculate the time we use the kinematic equations, where you assume a constant acceleration produced by the engines
vf = vo + a t
vf = 0 + a t
t = vf / a
t = 331/4 9.8
t = 8.44 s