Answer:
The object's acceleration is 3 m/s².
Step-by-step explanation:
Given that,
Speed = 9 m/s
Time = 3 sec
We need to calculate the acceleration
Using equation of motion

Where, v = final speed
u = initial speed
t = time
a = acceleration
Put the value into the formula



Negative sign shows the deceleration.
Hence, The object's acceleration is 3 m/s².