Answer:
a = 4.88 m / s²
Explanation:
We can solve this exercise using the expressions of kinematics in one dimension
v² = v₀² - 2a x
where v is the velocity, v₀ is the initial velocity, at acceleration and ax is the distance, the negative sign is because the velocity decreases because
a = (v₀² - v²) / 2x
let's calculate
a = (8.6² - 5.3²) / (2 4.7)
a = 4.88 m / s²