Answer:
a = 40 m / s²
Explanation:
For this exercise we can use the vertical launch equations to which these are valid in any system with inertial
v = v₀ + a t
a = (v-v₀) / t
We calculate
a = (90 - 10) / 2
a = 80/2
a = 40 m / s²
This is the value of the planet's gravity acceleration
