Answer:
4 m/s^2
Explanation:
The acceleration is defined as: Δv/Δt (the difference of the velocity over a time period in which happens that difference).
Remember that a difference is calculated by subtracting the initial value of a physical quantity from its final value.
In our case:
Δv = Vfinal - Vinitial = 36m/s - 0 m/s = 36m/s
Δt = 9s
a = Δv/Δt = 36m/s / 9s = 4m/s^2
