Answer:
  a = 5.53 g ,  a = -15g
Explanation:
This is an exercise in kinematics.
a) Let's look for the acceleration
     as part of rest v₀ = 0
     v = v₀ + a t
      a = v / t
      a = 282 / 5.2
     a = 54.23 m / s²
in relation to the acceleration of gravity
     a / g = 54.23 / 9.8
     a = 5.53 g
b) let's look at the acceleration to stop
     va = 0
     0 = v₀ -2 a y
     a = vi / y
     a = 282/2 1
     a = 141 m /s²
     a / G = 141 / 9.8
     a = -15g