Final answer:
The acceleration of the truck 12 seconds after starting from rest is 3.33 m/s².
Step-by-step explanation:
The acceleration of a truck after 12 seconds can be calculated using the formula:
acceleration = (final velocity - initial velocity) / time
Given that the truck started from rest and is now moving at 40 m/s, the final velocity is 40 m/s. Since the initial velocity is 0 m/s, the equation becomes:
acceleration = (40 m/s - 0 m/s) / 12 s = 3.33 m/s²
Therefore, the acceleration of the truck 12 seconds after starting from rest is 3.33 m/s².